An Atlas on Cephalometric Landmarks

CephalometriC landmarks

an atlas on

CephalometriClandmarks

JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD

New Delhi • London • Philadelphia • Panama

®

Basavaraj Subhashchandra PhulariBDS MDS (Ortho-TSMA-Russia) FAGE FRSH

FormerlyFaculty, Department of Orthodontics and

Dentofacial OrthopedicsMauras College of Dentistry, Hospital and

Oral Research InstituteRepublic of Mauritius

an atlas on

Jaypee Brothers Medical Publishers (P) Ltd

®

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An Atlas on Cephalometric Landmarks

First Edition: 2013ISBN: 978-93-5090-324-7

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HeadquartersJaypee Brothers Medical Publishers (P) Ltd4838/24, Ansari Road, DaryaganjNew Delhi 110 002, IndiaPhone: +91-11-43574357Fax: +91-11-43574314Email: [email protected]

ToMy dear parents Subhashchandra and Shivalingamma Phulari

brothers Sangamesh, Jagadish and Manjunathmy beloved wife Dr Rashmi GS

and my dear sons Yashas and Vrishank

Preface

Cephalometrics has been used in orthodontics for diagnosis, treatment planning, to evaluate the dentofacial changes during treatment and to assess the dentofacial growth and development. Cephalometrics makes use of certain landmarks on the skull. The first important step in cephalometric analysis is accurate location and tracing of cephalometric landmarks on the cephalogram. Any error in tracing the landmarks may result in incorrect cephalometric analysis. This book focuses on understanding the various cephalometric landmarks. Each cephalometric landmark is explained in detail including its abbreviation, definition by various researchers, origin and radiographic anatomy of the landmarks. There are 20 chapters divided into 11 sections. Chapter two lists the different ways of classifying cephalometric landmarks given in the literature. In addition, a new working classification has been given that lists the numerous cephalometric landmarks logically which makes remembering easier. This working classification is used as a blueprint to systemically explain the cephalometric landmarks from chapter 3 through chapter 19. Chapter 20 explains application of all types of cephalometric landmarks in various cephalometric analyses. In addition to the landmarks on lateral cephalogram, the landmarks on the posteroanterior (P-A) cephalogram and submentovertex (S-V) radiographic projection are also dealt in this book. I regret any deficiencies and shortcomings that might have crept in despite my best efforts. I would also welcome comments and suggestions from both students and teachers for further improvement of the book.

Basavaraj Subhashchandra Phulari [email protected]

Acknowledgments

I express my heartfelt gratitude to Dr Rajendrasinh Rathore MDS, Chairman of Manubhai Patel Dental College and Hospital, Vadodara, Gujarat for his inspirational support during this endeavor and throughout my career. I also thank Dr Yashraj Rathore, Trustee, Manubhai Patel Dental College and Hospital, Vadodara, Gujarat, India for encouraging me during this project. I am indebted to my dear parents for all their love and sacrifices that have made me what I am. My special thanks are due to my beloved wife for her valuable comments and suggestions, and my dear sons for being the constant source of inspiration to set and reach new goals in life. I would like to thank Anatomage Inc. for providing images in chapter 17 and for the cover. Most of all I thank the Almighty for all His kindness and blessings showered upon me.

Section 2: Classification of Cephalometric Landmarks

Contents

Section 1: Introduction and History

1. Cephalometry in Orthodontics ...................................................................................................... 3Technical Aspects 4Cephalometric X-ray Tracing Techniques 4

2. Classification of Cephalometric Landmarks ................................................................................ 7Classification of Cephalometric Landmarks (Points) 7

Section 3: Cephalometric Landmarks Related to Cranial Bones

3. Cephalometric Landmarks Related to Frontal Bone ................................................................. 15Parts of Frontal Bone 15Articulation of Frontal Bone 15Cephalometric Landmarks (Points) on Frontal Bone 15Radiographic Anatomy of Frontal Bone 15

Nasion 16Supra-Orbitale 17Roof of the Orbital Cavity 17Frontonasal/Fronto maxillary Nasal Suture 18

4. Cephalometric Landmarks Related to ethmoid bone .............................................................. 21Parts of Ethmoid Bone 21Articulation of Ethmoid Bone 21Cephalometric Landmarks (Points) on Ethmoid Bone 21Temporale 21

Neck of Crista Galli 23Medio-orbitale 23Sphenoethmoidal Point 24Ethmoidale 24

5. Cephalometric Landmarks Related to Nasal bone ................................................................... 26Articulation of Frontal Bone 26Radiographic Anatomy of nasal Bone 26Nasion 26

Frontonasal/Fronto maxillary Nasal Suture 28Rhinion 29

6. Cephalometric Landmarks Related to Temporal bone ............................................................ 31Articulation of Temporal Bone 31Radiographic Anatomy of Temporal Bone 31Cephalometric Landmarks (Points) on Temporal Bone 31

Porion 32Zygomatic Arch 32Mastiodale 33

7. Cephalometric Landmarks Related to Sphenoid bone ............................................................ 35Cephalometric Landmarks (Points) on Sphenoid Bone 35Dorsum of Sella 36Floor of Sella 37Clinoidale 38Spheno-Occipital Synchondrosis 39

Pterygoid Point 40Sella 41Sella Entrance 41Sphenoethmoidal point 42Pterygomaxillary Fissure 44

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Radiographic Anatomy of Zygomatic Bone 52Cephalometric Landmarks (Points) on Zygomatic Bone 52

Orbitale 52Temporale 54

8. Cephalometric Landmarks Related to Occipital bone ............................................................. 46

9. Cephalometric Landmarks Related to Zygomatic bone ............................................................ 52

Section 4: Cephalometric Landmarks Related to Facial Bones and Dentition

Section 5: Cephalometric Landmarks Related to Cervical Bones

13. Cephalometric Landmarks Related to Hyoid bone ................................................................ 101

14. Cephalometric Landmarks Related to Vertebrae ........................................................................ 103

Cephalometric Landmarks (Points) on occipital Bone 46Radiographic Anatomy of Occipital Bone 46basion 46

Opisthion 48bolton’s Point 48Spheno-Occipital Synchondrosis 50

10. Cephalometric Landmarks Related to Maxilla ........................................................................... 59Cephalometric Landmarks (Points) on Maxilla 59Anterior Nasal Spine 59Point A 61Prosthion 62

Posterior Nasal Spine 64Pterygomaxillary Fissure 65Key Ridge 66Orbitale 67

11. Cephalometric Landmarks Related to Dentition ........................................................................... 70Incision Superius Incisalis 71Incision Superius Apicalis 73Incision Inferius Incisalis 74Incision Inferius Apicalis 75Anterior Point of Occlusion 76Posterior Point of Occlusion 77

Maxillary Central Incisor 79Maxillary First Molar 79Mandibular Central Incisor 80Mandibular First Molar 81mi 82ms 83

12. Cephalometric Landmarks Related to Mandible ........................................................................... 85Cephalometric Landmarks (Points) on Mandible 85Parts of Mandible 85nerve Supply to Mandible 85Articulations 86Infradentale 86Point B 87Pogonion 88

Gnathion 89dd 91Menton 92Gonion 93Articulare 93kk 94Condylion 95

Parts of the Hyoid Bone 101Radiographic Anatomy of Hyoid Bone 101

Cephalometric Landmarks (Points) on Hyoid Bone 101Hyoid 101

Radiographic Anatomy of Cervical vertebrae 103Cephalometric Landmarks on Cervical vertebra 103Cephalometric Landmarks (Points) Related to Cervical vertebra 103

cv2ip 104cv2ap 104cv2ia 106cv3sp 106

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cv3ip 107cv3sa 107cv3ia 109cv4sp 109cv4ip 110cv4sa 110cv4ia 112cv5sp 112

cv5ip 113cv5sa 113cv5ia 115cv6sp 115cv6ip 116cv6sa 116cv6ia 118Cervical vertebrae as Indicators of Skeletal Maturity 118

Section 6: Cephalometric Landmarks Related to Pharynx

15. Cephalometric Landmarks Related to Pharynx ....................................................................... 123nasopharynx 123oropharynx 123Laryngopharynx 123Cephalometric Landmarks (Points) on Pharynx 123Anterior Nasal Spine, Posterior Nasal Spine and Pterygomaxillary Fissure 123Anterior Pharyngeal Wall 123

Posterior Pharyngeal Wall 124Superior Pharyngeal Wall 124Tip of the Uvula 124Point on the Oral Side of the Soft Palate 124Point on the Pharyngeal Side of the Soft Palate 124Upper Point of Tongue 124Significance 124

Section 7: Soft Tissue Cephalometric Landmarks

16. Soft Tissue Cephalometric Landmarks ......................................................................................... 127Soft Tissue Cephalometric Landmarks (Points) Related to Forehead 127Soft Tissue Glabella 127Soft Tissue Nasion 128Nasal Crown 129Pronasale 129Point “T” 130Alar Crease Junction 131

Subnasale 131Soft Tissue Subspinale 133Labrale Superius 134Stomion 135Labrale Inferius 136Soft Tissue Submentale 136Soft Tissue Pogonion 138Soft Tissue Gnathion 139

Section 8: 3D Cephalometric Landmarks

17. 3D Cephalometric Landmarks ................................................................................................... 143Vertex 143Soft Tissue Nasion 143Pronasale 144Subnasale 144Soft Tissue Subspinale 145Labrale Superius 146Stomion 146Labrale Inferius 146Soft Tissue Submentale 147Soft Tissue Pogonion 147Soft Tissue Gnathion 148Orbitale 148

Zygomatic Prominence 149Zygion 149Condylion 149Gonion 150Ch 150Cheilion 151Alare 151Exocanthion 151Sella 152Sella entrance 153basion 153Anterior Nasal Spine 154

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Section 9: PA Cephalometric Landmarks

18. PA Cephalometric Landmarks ................................................................................................... 159Taking PA Cephalogram 160Structures Involved in PA Cephalogram 160

Crista Galli 160Top of Nasal Septum 161NC 162Zyg-Zygoma 162Zygion 163Zygomatic Arch 163Zygomatic Suture Point 164Jugal Process 164Maxillare 165Incision Superius Incisalis 165Incision Superius Apicalis 166Maxillary Molar 167

Maxillary First Molar 168Cuspid 169Incision Inferius Incisalis 169Incision Inferius Apicalis 170Incision Inferius Frontale 171Mandibular First Molar 171mi 172Mandibular Molar 173Menton 173Articulare 174Malare 174Antegonial Tubercles 175Antegonion 175

Section 10: SV Cephalometric Landmarks

19. SV Cephalometric Landmarks ................................................................................................... 179basion 179Opisthion 179Foramina Spinosa Points 180Foramina Spinosum 180Odontoid 181Pterygomaxillary Fissure 182Middle Cranial Fossa Points 182Posterior Vomer Point 182Posterior Cranial Vault Points 183Angulare Point 184

Maxillary Apical Base Midline 185Mandibular Dental Midline 185Mandibular Apical Base Midline 186First Molar Point 187Gonion Point 187Condylion Medialis 188Condylion Lateralis 188Condylion Anterioris 189Condylion Posterioris 190

Section 11: Applications of Cephalometric Landmarks

20. Applications of Cephalometric Landmarks ............................................................................. 193Bjork Cephalometric Analysis 193Coben Craniofacial and Dentition Cephalometric Analysis 194Downs Cephalometric Analysis 195Farkas and Coworkers Soft Tissue Cephalometric Analysis 196Harvold Cephalometric Analysis 196

Holdaway Cephalometric Analysis 197Legan and Burstone Soft Tissue Cephalometric Analysis 198Rickett’s Cephalometric Analysis 198Sassouni Cephalometric Analysis 199Di Paolo’s Quadrilateral Analysis 200Hasund (Bergen) Cephalometric Analysis 200

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Jarabak Cephalometric Analysis 201Riedel Cephalometric Analysis 202Schwartz Cephalometric Analysis 203Wylie Cephalometric Analysis 203Steiner’s Cephalometric Analysis 204Tweed’s Cephalometric Analysis 205

Wit’s Cephalometric Analysis 206Basis Cephalometric Analysis 207Cagliari Cephalometric Analysis 207Chieti Cephalometric Analysis 208McGann Cephalometric Analysis 209

Index .....................................................................................................................................................211

Section1Introduction and History

CephalometryinOrthodontics

Cephalometric radiographs are used in orthodontic diagnosis to evaluate the pre-treatment dental and facial relationship of a patient, to evaluate changes during treatment and to assess tooth movement and facial growth at the end of treatment. On the cephalometric film, teeth can be related to one another, to the jaw in which they reside, and to cranial structures. The maxilla and mandible can be related to one another and other structures into the cranium and the soft tissue profile can be evaluated. Cephalometric analysis is one among various diagnostic aids. An orthodontic diagnosis is not possible only on the basis of cephalometry. Cephalometric analysis is an important aid in orthodontic diagnosis only if its findings are correctly and wisely interpreted with the help of other diagnostic aids. In the cephalometric assessment, certain carefully defined points are located on the radiographs, and linear and angular measurements are made from these points. The expressions of these measurements in various ways produce analysis of skeletal size and form.

Types of CephalogramThere are following two types of cephalograms 1. Lateral cephalogram: Lateral cephalogram provides a

lateral view of the skull (Fig. 1.1). It is taken with the head in a standardized reproducible position at a specified distance from the source of the x-ray. Lateral cephalogram commonly is used for cephalometric analysis.

2. Frontal cephalogram: This provides an antero-posterior view of the skull (Fig. 1.2).

Uses of Cephalometric Analysis

1. Cephalometric analysis is routinely used for diagnostic purpose to assess whether malocclusion dental or skeletal in origin.

2. It enables clinician to know accurately the extent to which patient deviates from described norms.

Figure 1.1: Lateral cephalogram Figure 1.2: Frontal cephalogram

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3. It is used to monitor the changes occurring due to growth or treatment or their combination. In other words, precise evaluation of patient’s response to treatment is made possible.

4. Yet another use of cephalometrics is to predict changes that should occur in future for patient after orthodontic treatment. An architectural plan / blueprint of orthodontic treatment.

Technical Aspects

The cephalometric radiographs are taken using an apparatus that consists of an x-ray source and a head holding device called cephalostat. The cephalostat consists of two ear rods that prevent the movement of the head in the horizontal plane. Vertical stabilization of the head is brought about by an orbital pointer that contacts the lower border of the left orbit. The upper part of the face is supported by the forehead clamp positioned above the region of the nasal bridge. The distance between the X-ray source and the mid-sagittal plane of the patient is fixed at 5 feet (152.4 cm). Thus the equipment helps in standardizing the radiographs by use of constant head position and source film distance so that serial radiographs can be compared. There are many systems of cephalometric analysis, which utilize various points and outline on the lateral cephalogram radiograph.

Cephalometric X-ray Tracing TechniquesMasking tape is used to attach the cephalometric x-ray to the acrylic acetate tracing paper sheet. Tracing is made on the frosted surface of acetate tracing sheet. The tracing is begun by marking the hard and soft tissue points needed for the analysis on the tracing sheet. Soft tissue profile is traced and then the sella turcica going forward to the planum sphenoidale along the floor of the anterior cranial fossa of the shadows of the greater wings of sphenoid bone are

traced. The anterior surface of the frontal and nasal bones are then traced followed by tracing the outline of the maxilla and from the anterior nasal spine along the floor of the nasal cavity back to posterior nasal spine from posterior nasal spine.

Bibliography 1. Bennett GC, Kronman JH. A cephalometric study of mandibular

development and its relationship to the mandibular and occlusal planes. Angle orthodont.1970;40:119-28.

2. Bjork A. Prediction of mandibular growth rotation. Am J Orthodont. 1969;55:585-99.

3. Broadbent BH. A new X-ray technique and its application to orthodontics, Angle Orthod. 1931;1:45-66.

4. Brodie AG, Downs WB, Goldstein A, Myer E. Cephalometric appraisal of orthodontic results: A preliminary report. Angle orthodont. 1938;8:261-5.

5. Downs WB, Variations if facial relationship: Their significance in treatment and prognosis. Am J Orthod. 1948;34:812.

6. Downs WB. Analysis of the dentofacial profile. Angle Orthod. 1956; 26:191.

7. Downs WB. Analysis of the dento-facial profile. Angle orthodont. 1956;26:191-212.

8. Houston WJB. The analysis of error in orthodontics measurements. AM J Orthod. 1983;83:382-90

9. Jacobs. Introduction to Radiographic Cephalometry, Lea and Febiger, Philadelphia. 1985.

10. Jacobson A. Radiographic cephelometry: From basics to video imaging, Chicago 1995, Quintessence Pub Co.

11. Jacobson A. The appraisal of jaw disharmony. Am J Orthod. 1975; 67:125-38.

12. Jakobson S. Cephelometric evaluation of treatment effect on Class-IIDivision I malocclusions. Amer J Orthodont. 1967;53:446-57.

13. Moorrees, CFA, Lebret L. The mesh diagram and cephalometricss. Angle Orthodont. 1962;32:214-31.

14. Rickets RM, Bench RW, Hilgers JJ, Schulhof R. An overview of computerized cephalometrics. Am J Orthodont. 1972;61:1-28.

15. Steiner CC. The use of Cephalometrics as an aid in planning & assessing orthodontic treatment. Am J Orthod. 1960;46:721.

16. Subtelny JD. Cephalometric diagnoss, growth and treatment: something old, something new? Am J Orthodont. 1970;57:262-86.

17. Susomi R. A cephalometric evaluation of dentofacial growth in mandi-bular protrusion subjects. J Osaka Univer. Dent. CSch. 1969;9:25-35.

18. Thomas M Graber, Robert L Vanarsdall. Orthodontics current principles and techniques, Mosby year book Inc. 1994.

19. Tweed CH. The diagnosis facial triangle in the control of treatment objectives. Am J Orthodont. 1969;55:667.

2Classification of Cephalometric

Landmarks

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2 Classification of Cephalometric Landmarks

Cephalometry makes use of certain landmarks or points on the skull which are used for quantitative analysis and measurements.

Classification of cephalometric landmarks/pointsThe first two classifications given below are well-known in the literature. In addition to these basic existing classifications, the author has attempted to categorize the cephalometric landmarks in various ways to simplify their understanding and subsequent applications in various cephalometric analysis.

Classification of cephalometric landmarks based on OriginBased on the origin, cephalometric landmarks/points are classified in the following two types (Flow chart 2.1): 1. Anatomic cephalometric landmarks/points. 2. Derived cephalometric landmarks/points.

1. Hard tissue cephalometric landmarks. 2. Soft tissue cephalometric landmarks.

Flow chart 2.1: Cephalometric landmarks/points

Anatomic cephalometric landmarks/pointsThese landmarks represent the actual anatomic structures of the skull, e.g. Nasion, point A, point B, ANS, PNS, etc.

Derived cephalometric landmarks/pointsThese are landmarks that have been obtained secondarily from anatomic structures in a lateral cephalogram, e.g. Gnathion, Anterior Point of Occlusion, etc.

cephalometric landmarks Based on Structures Involved Based on structures involved, cephalometric landmarks/points can be classified as follows (Flow chart 2.2):


Hard tissue cephalometric landmarksThese landmarks represent the actual hard tissue structures of the skull, such as nasal bone, ethmoidal bone, frontal bone, maxillary bone, mandible and hyoid, etc.

Examples of hard tissue cephalometric landmarks—• Nasion • Neck of crista galli• Temporale• Sella• Menton• Gonion.

Soft tissue cephalometric landmarksCephalometric landmarks/points located on soft tissues are categorized as soft tissue cephalometric landmarks/points.

Soft tissues:• Forehead • Nose• Lips• Chin.

Examples of soft tissues cephalometric landmarks—• Soft tissue nasion• Subnasale• Subspinale• Stomion• Soft tissue pogonion• Soft tissue gnathion.

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• Point B• Menton, etc.

Bilateral cephalometric landmarks

These are cephalometric landmarks found on both right and left side.Examples• Gonion• Articulare• APOcc• U 6• L 6, etc.

Hard or Soft Tissue Cephalometric landmarks

Cephalometric landmarks/points can be hard or soft tissue landmarks. Hard tissue and soft tissue landmarks can be further classified into anatomic and derived and then subclassified into unilateral or bilateral (Flow chart 2.4).

Cephalometric Landmarks/Points can be Found on lateral Cephalogram, PA Cephalogram and SV Cephalogram (Flow Chart 2.5)


Cephalometric landmarks Based on the type or Side InvolvedBased on the side involved cephalometric landmarks/points can be classified as follows (Flow chart 2.3): 1. Unilateral cephalometric landmarks. 2. Bilateral cephalometric landmarks.


Unilateral cephalometric landmarks

These are cephalometric landmarks or points situated in the midline.Examples• Nasion• Neck of crista galli• Point A

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Types of Cephalometric Landmarks/PointsCephalometric landmarks/points can be classified into follow-ing three types (Flow chart 2.6) 1. Cephalometric landmarks/points related to cranial bones 2. Cephalometric landmarks/points related to pharynx 3. Cephalometric landmarks/points related to cervical vertebrae



B C

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Classification of Cephalometric Landmarks/Points Based on their LocationThe detailed description of the cephalometric landmarks/points in this book follows this working classification (Flow chart 2.7).

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Cephalometric landmarks/points related to cranial bones

cephalometric landmarks/points related to frontal Bone

• Nasion • Supra-orbitale• Roof of orbit• Frontozygomatic suture• Frontale • Frontomaxillary nasal suture

cephalometric landmarks/points related to ethmoid Bone

• Temporale • Neck of crista galli• Medio-orbitale• Sphenoethmoidal point• Ethmoidale

cephalometric landmarks/points related to nasal Bone• Nasion • Rhinion• Frontonasal/frontomaxillary nasal suture

cephalometric landmarks/points related to temporal Bone

• Porion • Zygomatic arch• Mastiodale

cephalometric landmarks/points related to sphenoid Bone

• Dorsum sella• Floor of sella• Clenoidale • Spheno-occipital synchondrosis• Pterygoid point• Pterygomaxillary fissure• Foramen spinosum point• Sella• Sphenoethmoidal point

cephalometric landmarks/points related to occipital Bone• Basion• Opisthion• Bolton’s point• Spheno-occipital synchondrosis

cephalometric landmarks/points related to zygomatic Bone

• Orbitale• Temporale

Cephalometric landmarks/points related to Facial Bone and Dentition

cephalometric landmarks/points related to maxilla

• Anterior nasal spine• Point A• Anterior point of occlusion• Prosthion• Posterior nasal spine• Pterygomaxillary fissure• Key ridge• Orbitale

cephalometric landmarks/points related to dentition

• Incision superius incisalis• Incision superius apicalis• Incision inferius incisalis• Incision inferius apicalis• Anterior point of occlusion• Posterior point of occlusion• Maxillary central incisor• Maxillary first molar• Mandibular central incisor• Mandibular first molar• Mi• Ms

cephalometric landmarks/points related to mandible

• Infradentale • Point B• Pogonion• Gnathion• dd• Menton• Gonion• Articulare• kk• Condylion

cephalometric landmarks/points related to cervical Bones

Cephalometric landmarks/points related to hyoid bone• Hyoid.

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cephalometric landmarks/points related to vertebrae • Nasal crown• Pronasale• Point T

3. Soft tissue cephalometric landmarks or points related to lipsUpper lip• Soft tissue subspinale• Labrale superius• Philtrum• Cuspid bow• Vermilion border of upper lipsLower lip• Labrale inferius• Soft tissue point BUpper and lower lips• Stomion - Stomion superius - Stomion inferius

4. Soft tissue cephalometric landmarks/points related to chin• Soft tissue pogonion• Soft tissue menton• Soft tissue gnathion.

• cv2ap• cv2ip• cv2ia• cv3sp• cv3ip• cv3sa• cv3ia• cv4sp• cv4ip• cv4sa

• cv4ia• cv5sp• cv5ip• cv5sa• cv5ia• cv6sp• cv6ip• cv6sa• cv6ia

Soft tissue cephalometric landmarks/pointsSoft tissue cephalometric landmarks or points can be classified as follows (Flow chart 2.8): 1. Soft tissue cephalometric landmarks or points related to

forehead• Trichion• Soft tissue glabella.

2. Soft tissue cephalometric landmarks or points related to nose• Soft tissue nasion

Flow chart 2.8: Soft tissue cephalometric landmarks/points

Section3Cephalometric Landmarks Related to Cranial Bones

Cephalometric Landmarks Related to Frontal Bone Cephalometric Landmarks Related to Ethmoid Bone Cephalometric Landmarks Related to Nasal Bone Cephalometric Landmarks Related to Temporal Bone Cephalometric Landmarks Related to Sphenoid Bone Cephalometric Landmarks Related to Occipital Bone CephalometricLandmarksRelatedtoZygomaticBone

The frontal bone (Fig. 3.1) (Os frontale in Latin), is a membranous bone that forms the anterior part of the cranial vault. The frontal is like half a shallow, irregular cap forming the forehead or form on each side a horizontal orbital part roof of most of an orbital cavity. The frontal bone is thick with trabecular tissue between compact laminae, trabecular being absent near the frontal sinuses.

Parts of Frontal BoneParts of frontal bone are listed below:• Squamous part• Orbital plates• Nasal process• Zygomatic process.

Articulation of Frontal BoneThe frontal bone articulates with 12 bones in total and is listed below:• Paritalbone • Sphenoidbone• Ethmoidbone • Maxillarybone• Nasalbone • Lacrimalbone• Zygomaticbone • Temporalbone

Cephalometric Landmarks (Points) on Frontal BoneCephalometric landmarks seen on the frontal bone are of anatomic origin and are as follows (Table 3.1):

Table 3.1: Cephalometric landmarks (points) related to frontal bone

Cephalometric landmarks Abbreviation Type Origin

Nasion N or Na Unilateral Anatomic

Supra-orbitale SOr Bilateral Anatomic

Roof of orbit RO Bilateral Anatomic

Frontomaxillary nasalsuture

FMN Unilateral Anatomic

Radiographic Anatomy of Frontal Bone (Fig. 3.2)

On lateral cephalogram, the inner and outer cortical plates of frontal bone appear as two parallel radio-opaque lines descending downwards from coronal suture. Anterio-inferiorly, these two radio-opaque lines diverge to encase the frontal sinus, which appears radiolucent area.

The outer radio-opaque line representing outer cortical plates meets nasal bone at frontonasal suture, while the inner radio-opaque line representing inner cortical plate meets

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Figure 3.1: Frontal boneFigure 3.2: Radiographic anatomy of the frontal bone on the

lateral cephalogram

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Nasion

AbbreviationN–Nasion is abbreviated using English alphabet and isexpressedascapitalletteroruppercaseN.

DefinitionNasion (Figs 3.3A to D) is the most anterior point of the frontonasal suture in the middle.1

ethmoid bone at frontoethmoidal suture. Above the horizontal part of the internal cortical plate, there are two radio-opaque lines. The upper radio-opaque line represents endocranial surface of the frontal bone, which forms the base for anterior cranial fossa, and the other radio-opaque line represents the exocranialsurfaceofthefrontalbonewhichformstheroofofthe orbit.

Figures 3.3A to D: (A) Nasion on lateral cephalogram; (B) Magnified image showing nasion on the lateral cephalogram; (C) Nasion on graphic illustration; and (D) Magnified image of nasion on graphic illustration

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According to Willam B DownsNasion is the suture between the frontal and nasal bones.1

According to TM GraberNasion is the junction of the nasal and frontal bone as seen on theprofileofthecephalometricroentgenogram.2

According to B Holly BroadbentNasion is the craniometric point where the midsagittal plane intersects the most anterior point of the frontonasal suture, the anterior termination of the Bolton’s plane.3

According to Leslie G FarkasNasion is the point in the midline of both the nasal root and the frontonasal suture.4

TypeNasion is a unilateral, anatomic, hard tissue cephalometric landmark (Point).

OriginNasion is a hard tissue cephalometric landmark of anatomic origin.

Tracing of Nasion on the Lateral CephalogramThe outer cortical plate of frontal bone, nasal bone and frontonasal suture appears as radio-opaque line on the lateral cephalogram. The outer cortical plate of frontal bone is denser radio-opaque than compared to other two bony structures. Trace outer cortical plate of frontal bone, nasal bone and frontonasal suture, the point in the midline where all three structures meet is the point of nasion. In other way nasion is the most anterosuperior point on the frontonasal suture in the midline.

Significance (Ref to Chapter 20)Nasion is used as one of the reference points in the construction of angles and planes for the assessment of following:• Relationshipofmaxillatocranialbaseisassessedusing

SNA angle.• Relationship of mandible to cranial base is assessed using

SNB angle.• Maxillo-mandibular relationship with anterior cranial

base is assessed using ANB angle.• Inclination upper incisors are assessed using NA-Upper

incisor angular and NA-Upper incisor linear.• Inclination lower incisors are assessed using NB-Lower

incisor angular and NB-Lower incisor linear.

• Relationship of anterior and posterior cranial base is assessed using N-S-Ar angle.

Supra-Orbitale

AbbreviationSOr–Supra-orbitale is abbreviated using English alphabetsand is expressed as capital or upper caseS,O followedbylower case r and is written continuously without any space between the alphabets.

Definition

According to Viken SassouniSupra-orbitale (Figs 3.4A to D) is the most anterior point of the intersection of the shadow of the roof of the orbit and its lateral contour.5

TypeSupra-orbitale is a bilateral, hard tissue lateral cephalo metric landmark (point).

OriginSupra-orbitale is a hard tissue cephalo metric landmark of anatomic origin.

Tracing the Supra-Orbitale on the Lateral CephalogramSupra-orbitale, the point on the orbital margin where it turns onto the upper roof of the orbital cavity, is comparatively easy to trace.

Significance (Ref to Chapter 20)• Supra-orbitale is useful reference point for anteroposterior

differences and vertical differences between the right and left sides when the orbits are traced.

• Supra-orbital landmark is used as a landmark in Sassouni cephalometric analysis.

Roof of the Orbital Cavity

AbbreviationRO–RoofoftheorbitalcavityisabbreviatedusingEnglishalphabets and is expressed as capital or upper case R, Oand is written continuously without any space between the alphabets.

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DefinitionThe roof of the orbital cavity is formed by the bone between the anterior cranial fossa above and the orbital cavity below.

According to Viken SassouniThe roof of the orbit is the uppermost point of the orbit.5

TypeRoof of the orbital cavity (Figs 3.5A to D) is a bilateral, anatomic hard tissue lateral cephalometric landmark.

Tracing the Roof of Orbit on the Lateral CephalogramOn the cephalogram, both right and left roofs of the orbital cavity are superimposed and reveal as a radio-opaque line anteriorly and posteriorly leading to pituitary fossa.

Frontonasal/Fronto maxillary Nasal Suture

Abbreviation

FMN–Frontomaxillary suture is abbreviated using EnglishalphabetsandisexpressedascapitaloruppercaseF,MandN and are written continuously without any space between the alphabets.

Definition

Frontomaxillary nasal suture (Figs 3.6A to D) is the most superiorpointofthesuture,wherethemaxillaarticulateswiththe frontal and nasal bones.

Figures 3.4A to D: (A) Supra-orbitale on lateral cephalogram; (B) Magnified image showing supraorbitale on the lateral cephalogram; (C) Supra-orbitale on graphic illustration; and (D) Magnified image of supra-orbitale on graphic illustration

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Figures 3.5A to D: (A) Roof of orbit on lateral cephalogram; (B) Magnified image showing roof of orbit on the lateral cephalogram; (C) Roof of orbit on graphic illustration; and (D) Magnified image of roof of orbit on graphic illustration

Figures 3.6A to D: (A) Frontomaxillary suture on lateral cephalogram; (B) Magnified image showing frontomaxillary suture on the lateral cephalogram; (C) Frontomaxillary suture on graphic illustration; and (D) Magnified image of frontomaxillary suture on graphic illustration;

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TypeFrontomaxillary nasal suture is a unilateral, anatomic, hardtissue cephalometric landmark.

Significance (Ref to Chapter 20)

Frontomaxillary nasal suture is situated/located on anteriorcranial base, unlike N and can therefore also be used for measurementordefiningthecranialbase(Moyers1988).

References 1. Downs WB. Variations in facial relationships. Their significance in

treatmentandprognosis.AmJofOrtho.1948;34:812-39. 2. GraberTM.Newhorizonsincaseanalysis-clinicalcephalometrics.Am

JofOrtho.1952;38:603-24. 3. Broadbent BH Sr. Bolton’s standards of dentofacial developmental

growth.TheCVMosbyCompany.1975;133-5. 4. FarkasLG.Anthropometryoftheheadandfaceinmedicine—Elsevier

North Holland, Inc.1981;9-14. 5. SassouniV.Orthodonticsindentalpractice.TheCVMosbyCompany.

1971;330-7.

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4 Cephalometric landmarks related to ethmoid bone

The ethmoid bone (Fig. 4.1) (Os ethmoidale in Latin). The Ethmoid bone is cuboidal and fragile, lies anterior in the cranial base and is involved in the structure of the orbital walls and nasal septum, the roof and lateral walls of the nasal cavity. It is described as a heavy horizontal cribriform plate, a median plate and two total labyrinths.

Parts of Ethmoid BoneParts of ethmoid bone are listed below:• Cribriform plate• Crista galli• Perpendicular plate.

Articulation of Ethmoid BoneThe ethmoid bone articulates with 13 bones in total and is listed below:• Sphenoid bone• Frontal bone

• Lacrimal bone – (2)• Palatine bone – (2)• Vomer• Maxillary bone – (2)• Inferior nasal concha – (2)• Nasal bone – (2).

Cephalometric Landmarks (Points) on Ethmoid BoneCephalometric landmarks seen on the ethmoid bone are of anatomic origin and are as follows (Table 4.1):

Table 4.1: Cephalometric landmarks (points) related to ethmoid bone


temporale te Bilateral anatomic

Neck of the crista galli NC Unilateral anatomic

Medio-orbitale mo Bilateral anatomic

Sphenoethmoidal point Se Unilateral anatomic

ethmoidale eth Unilateral anatomic

Radiographic Anatomy of Ethmoid Bone (Fig. 4.2)On the lateral cephalogram, the cribriform plate of the ethmoid bone is seen, which appears as a radio-opaque line below the horizontal part of the internal cortical plate of the frontal bone. The intersection of the shadows of the ethmoid and the anterior walloftheinfratemporalfossaisidentifiedastemporalandisabilateral hard tissue cephalometric landmark. The intersection of the shadows of the greater wing of the sphenoid and the cranialfloorisidentifiedasSphenoethmoidal(SE).

Temporale

AbbreviationTe–Temporale is abbreviated using English alphabets and is expressed as capital or upper case T followed by small letter Figure 4.1: ethmoid bone

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or lower case e and is written continuously without any space between the alphabets.

Definition

Temporale (Figs 4.3A to D) is the intersection of the shadows of the ethmoid and the anterior wall of the infra-temporal fossa.

According to Viken Sassouni

Intersection of the shadows of the ethmoid and anterior wall of the infra-temporal fossa.1

Type

Temporale (Figs 4.3A to D) is a bilateral, anatomic, hard tissue cephalometric landmark.

Figures 4.3A to D: (A) Temporale on lateral cephalogram; (b) Magnified image showing temporale on the lateral cephalogram; (C) Temporale on graphic illustration; and (D) Magnified image of temporale on graphic illustration

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Figure 4.2: radiographic anatomy of ethmoid bone

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Neck of Crista Galli

AbbreviationNC–Neck of Crista Galli is abbreviated using English alpha-bets and is expressed as capital or upper case N and C and is written continuously without any space between the alphabets.

Definition

According to Viken SassouniNeck of the crista galli (Figs 4.4A and B) is the most constricted point of the projection of the perpendicular lamina of the ethmoid (almost at the level of planum).1

TypeNeck of crista galli is an anatomic, unilateral, hard tissue cephalometric landmark.

Significance (Ref to Chapter 20)• The crista galli is an important landmark of the midline

for the analysis of bilateral symmetry in a posteroanterior cephalogram.

• Crista galli lies behind the frontal sinuses on the lateral cephalogram and in the central part of the cranium on the posteroanterior cephalogram.

Tracing Neck of Crista Galli on The Lateral Cephalogram

ItisdifficulttoidentifyonthelateralcephalogramwhereasitcanbeeasilyidentifiedonthePAcephalogram.

Medio-orbitale

Abbreviationmo–Medio-orbitale is abbreviated using English alphabets and is expressed as lower case m, o and written continuously without any space between the alphabets.

Definition

According to Athanasios E Athanasiou

Medio-orbitale (Figs 4.5A and B) is the point on the medial orbital margin that is closest to the median plane.2

Figures 4.4A and B: (A) Neck of crista galli on frontal cephalogram; (b) Magnified image showing neck of crista galli on the frontal cephalogram

Figures 4.5 A and B: Medio-orbitale on the lateral cephalogram; (b) Magnified image showing medio-orbitale on the lateral cephalogram

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TypeMedio-orbitale is an anatomic, bilateral, hard tissue cephalo-metric landmark.

Sphenoethmoidal Point

AbbreviationSE–Sphenoethmoidal point is abbreviated using English alphabets and is expressed as upper case S, E and written continuously without any space between the alphabets.

Definition

According to Robert E MoyersThe intersection of the shadows of the grater wing of the sphenoid and the cranial floor as seen in the lateralcephalogram3 (Figs 4.6A to D).

According to SN Bhatia and BC LeightonThe point of intersection between the greater wings of the sphenoid and the anterior cranial base.4

TypeSphenoethmoidal point is an anatomic, unilateral, hard tissue cephalometric landmark.

Ethmoidale

AbbreviationEth–Ethmoidale is abbreviated using English alphabets and is expressed as capital or upper case E and small alphabets or lower case th and written continuously without any space between the alphabets.

Figures 4.6A to D: Sphenoethmoidale: (A) Sphenoethmoidale on the lateral cephalogram; (b) Magnified image showing sphenoethmoidale on the lateral cephalogram; (C) Sphenoethmoidale on graphic illustration; and (D) Magnified image of sphenoethmoidale on graphic illustration

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Definition

According to Arne BjorkThe deepest median point of the anterior cranial fossa, corres-ponding to the cribriform plate of the ethmoid bone.5

According to SN Bhatia and BC LeightonEthmoidale (Figs 4.7A to D) is the lowest point on the anterior cranial fossa or the outline of the cribriform plate.4

TypeEthmoidale is an anatomic, unilateral, hard tissue cephalo-metric landmark.

References 1. Viken Sassouni—Orthodontics in dental practice. The CV Mosby

Company. 1971:330-7. 2. Athanasios E Athanasiou, Helmut Drioschk, Charles Bosch. Data

and patterns of transverses dentofacial structure of 6 to 15 years–old children;Aposteroanteriocephalometricstudy.

3. Robert M Moyers. Handbook of Orthodontics. Year Book Medical Publishers, Inc. 1988:251-9.

4. BhatiaSN,LeightonBC.Amanualoffacialgrowth–OxfordUniversityPress. 1993:10-5.

5. ABjork.Thefaceinprofiles-Sven.TandlakTidskr.1947;40:32-3.

Figures 4.7A to D: ethmoidale: (A) ethmoidale on the lateral cephalogram; (b) Magnified image showing ethmoidale on the lateral cephalogram; (C) ethmoidale on graphic illustration; and (D Magnified image of ethmoidale on graphic illustration

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5 Cephalometric Landmarks Related to Nasal Bone

The nasal bone (Fig. 5.1) (Os nasale in Latin), are paired bones that lie in the midline above the nasal fossae between the frontal processes of the maxilla. They articulate superiorly with the frontal bone at the fronto-nasal suture.

Articulation of Frontal Bone The nasal bone articulates with four bones in total and is listed below:• Maxilla • Frontal bone • Ethmoid bone • Nasal bone of opposite side.

Cephalometric Landmarks (Points) on Nasal BoneCephalometric landmarks seen on the nasal bone are of anatomic origin and are as follows (Table 5.1):

Table 5.1: Cephalometric landmarks related to nasal bone

Cephalometric landmarks Abbreviation Type Orgin

Nasion N OR Na Unilateral Anatomic

Frontonasal/frontomaxillary nasal suture

FMN Unilateral Anatomic

Rhinion Rh Unilateral Anatomic

Radiographic Anatomy of Nasal Bone (Fig. 5.2)On lateral cephalogram, the nasal bone appears as a triangular radio-opaque area. Its apex points to the tip of the nose and its base faces the frontonasal suture which appears as an oblique radiolucent line between frontal and nasal bones. The posterior part of the inner surface of the nasal bone merges with the radio-opaque line of the cribriform plate of the ethmoid bone. The anteromedial point of the frontonasalsutureisidentifiedasnasionandposteroinferiorpointisidentifiedasFMN.

Nasion

AbbreviationN–Nasion is abbreviated using English alphabet and is expressed as capital letter or upper case N.

Figure 5.1: Nasal bones Figure 5.2: Radiographic anatomy of nasal bone

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DefinitionNasion (Figs 5.3A to D) is the most anterior point of the frontonasal suture in the middle.

According to TM GraberNasion is the junction of the nasal bone and frontal bones as seenontheprofileofthecephalometricroentgenogram.1

According to B Holly BroadbentNasion is the craniometric point where the midsagittal plane intersects the most anterior point of the frontonasal suture; the anterior termination of the Bolton plane.2

According to William B DownsNasion is the suture between the frontal and nasal bone.3

TypeNasion is a unilateral, anatomic, hard tissue cephalometric landmark.

OriginNasion is a hard tissue cephalometric landmark of anatomic origin.

Figures 5.3A to D: (A) Nasion on lateral cephalogram; (B) Magnified image showing nasion on the lateral cephalogram; (C) Nasion on graphic illustration; and (D) Magnified image of nasion on graphic illustration

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Significance (Ref to Chapter 20)Nasion is used as one of the reference point in the construction of angles and planes for the assessment of the following:• Relationship of maxilla to cranial base is assessed using

SNA angle.• Relationship of mandible to cranial base is assessed

using SNB angle.• Maxillo-mandibular relationship with anterior cranial

base is assessed using ANB angle.• Inclination upper incisors are assessed using NA-Upper

incisor angular and NA-Upper incisor linear.• Inclination lower incisors are assessed using NB-Lower

incisor angular and NB-Lower incisor linear.• Relationship of anterior and posterior cranial base

assessed using N-S-Ar angle.• In McNamara cephalometric analysis, the cant of the

upper lips is evaluated by constructiong an angle using a line tangent to the upper lip and the nasion. The nasion perpendicular is a vertical line drawn perpendicular to Frankfort horizontal plane.

• Anteroposterior orientation of the maxilla to the cranial base is assessed by the linear distance between nasion perpendicular and point A. An anterior position of point

A is a positive value and a posterior position of point A is a negative value.

• In Rickett’s cephalometric analysis, the positioning of the chin is determined by the angle formed between the Ba-N plane and plane from foramen rotundum (PT) to Gn. The normal value of this angle is 90 degree. A larger angle suggests a protrusive or forward growing chin whereas a lesser angle suggests a retropositioning of the chin.

Frontonasal/Fronto maxillary Nasal Suture

AbbreviationFMN–Frontomaxillary suture is abbreviated using English alphabets and is expressed as capital F, M and N and is written continuously without any space between the alphabets.

DefinitionFrontomaxillary nasal suture (Figs 5.4A to D) is the most superior point of the suture, where the maxilla articulates with the frontal and nasal bones.

Figures 5.4A to D: (A) Frontomaxillary nasal suture on lateral cephalogram; (B) Magnified image showing frontomaxillary nasal suture on the lateral cephalogram; (C) Frontomaxillary nasal suture on graphic illustration; and (D) Magnified image of frontomaxillary nasal suture on graphic illustration

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According to Robert M MoyersAccording to Robert M Moyers, frontomaxillary nasal suture is the most superior point of the suture, where the maxilla articulates with the frontal and nasal bones.4

TypeFrontomaxillary nasal suture is a unilateral, hard tissue cephalo-metric landmark.

OriginFrontomaxillary nasal suture is a hard tissue cephalometric landmark of anatomic origin.

Significance (Ref to Chapter 20)Frontomaxillary nasal suture is situated/located on anterior cranial base, unlike N and can therefore also be used for measure-mentordefiningthecranialbase(Moyers1988).

Rhinion

AbbreviationRh–Rhinion is abbreviated using English alphabets and is ex-pressed as capital or upper case R followed by lower case h, and is written continuously without any space between the alphabets.

Definition

According to Spiro J Chaconas According to Spiro J Chaconas, Rhinion (Figs 5.5A to D) is the most anterior-inferior point on the tips of the nasal bones as seen from norma lateralis.5

TypeRhinion is an anatomic, unilateral, hard tissue cephalometric landmark.

Figures 5.5A to D: (A) Rhinion on lateral cephalogram; (B) Magnified image showing Rhinion on the lateral cephalogram; (C) Rhinion on graphic illustration; and (D) Magnified image of Rhinion on graphic illustration

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Tracing Rhinion on the Lateral CephalogramTracingtherhinionisdifficultinfewcases,wherethereisfadedimage of nasal bone in the tip region, in such cases the margin of the piriform aperture will be helpful in identifying the point rhinion. In most of the cases it is easy to identify on the lateral cephalogram. Trace the nasal bone from the frontonasal suture till the tip, the tip of the nasal bone is the point of rhinion.

Significance (Ref to Chapter 20)Position of rhinion differs from individual to individual. As we learnt in anatomy, there are several types of nasal

bone, especially its inclination that affects the soft tissue profile.

References 1. Graber TM. New horizons in case analysis-clinical cephalometrics. Am

JofOrtho.1952;38:603-24. 2. Broadbent BH Sr. Bolton’s standards of dentofacial developmental

growth. The C V Mosby Company. 1975;133-5. 3. Downs WB. Variations in facial relationships. Their significance in

treatmentandprognosis.AmJofOrtho.1948;34:812-39. 4. Moyers RM. Handbook of Orthodontics–Year Book Medical Publishers,

Inc.1988;251-9. 5. SpiroJChaconas.Orthodontics-PSGPublishingCompany.1980;37-45.

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6 Cephalometric landmarks related to temporal bone

Each temporal bone consists of following two portions (Fig. 6.1):• Squamous portion• Petrous portion. Squamousportionof the temporalbone is largeandflatthat forms the lateral wall of the cranium. Petrous portion of temporal bone is an irregular bone which forms the inferior part of the temporal bone.

Articulation of Temporal Bone Superiorly temporal bone articulates with parietal bone at squamoparietal suture. Inferiorly, it articulates with mandibular condyle at genoid fossa. Zygomatic process of temporal bone articulates wih zygomatic bone at zygomaticotemporal suture. The major part of the temporal bone that can usually be identified from the lateral cephalogram is the endocranialsurface of the petrous portion. It appears as a triangular radio-opaque area with its apex pointing upwards and backwards. The side of the triangle that appears as the anterosuperior radio-opaque line represents the posteroinferior limit of the middle cranial fossa. This radio-opaque line continues anteriorly to the endocranial surface of the squamous portion of the temporal bone and the greater wing of the sphenoid

bone. The other side of the triangle, which appears as a vertical line, represents the anterior limit of the posterior cranial fossa.

Radiographic Anatomy of Temporal Bone (Fig. 6.2)Themajorpartofthetemporalbonethatcanusuallybeidentifiedfrom the lateral cephalogram is the endocranial surface of the petrous portion. It appears as a triangular radio-opaque area with its apex pointing upwards and backwards.The side of the triangle that appears as the anterosuperior radio-opaque line represents the posteroinferior limit of the middle cranial fossa. This radio-opaque line continues anteriorly to the endocranial surface of the squamous portion of the temporal bone. The other side of the triangle, which appears as a vertical line, represents the anterior limit of the posterior cranial fossa.

Cephalometric Landmarks (Points) on Temporal BoneCephalometric landmarks seen on the temporal bone are of anatomic origin and are as follows (Table 6.1):

Figure 6.1: temporal bone Figure 6.2: radiographic anatomy of temporal bone

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Table 6.1: Cephalometric landmarks related to temporal bone

Cephalometric landmarks

Abbreviation Type Origin

porion po Bilateral anatomicZygomatic arch Zyg Bilateral anatomicMastoidale Ma Bilateral anatomic

Porion

AbbreviationPo–Porion is abbreviated using English alphabets and is ex-pressed as capital letter or upper case P followed by lower case o, and is written continuously without any space between the alphabets.

DefinitionPorion is the most superior point of the external auditory meatus (the superior margin of the TMJ fossa, which lies at the same level may be substitute in the construction of the FH).

According to Arne Bjork The midpoint of the upper edge of the porous acoustics externus located by wings of the metal rods on the cephalometer. This is the cephalometric reference point.1

According to Willam B DownsThe highest point on the superior surface of the soft tissue of the external auditory meatus.2

According to LB HigleyThe highest point on the roof of the left external auditory meatus.3

According to Robert E MoyersThe top of the ear rods Shadows the external auditory meatus.4

According to B Holly BroadbentPoint on the upper margin of the porus acusticus externus the two poriaandleftorbitaledefinedtheFrankforthorizontalplane.5

According to Leslie G FarkasPorion (soft) is the highest point on the upper margin of the cutaneous auditory meatus.6

TypePorion (Figs 6.3A to D) is a bilateral, hard tissue cephalometric landmark.

OriginPorion is a hard tissue cephalometric point of anatomic origin.


1. Porion is used as one of the reference points in the construction of Frankfort horizontal plane and is used for the assessment of horizontal growth pattern using following angles:• FH-Mandibular plane angle (Go-Me) • FH-Palatal plane angle (ANS-PNS) • FH-Occlusal plane (APOcc – PPOcc)

2. Porion is also used as one of the reference points in the construction of angle and is used for the assessment of upper incisors torque using FH—long axis of upper incisors.

Zygomatic Arch

AbbreviationZyg–Zygomatic arch is abbreviated using English alphabets and is expressed as capital or upper case Z followed by lower case y and g, and is written continuously without any space between the alphabets.

Definition

According to Robert M RickettsAccording to Robert M Ricketts, the Zygomatic arch is the center of zygomatic arch by inspection for frontal.7

TypeZygomatic arch is bilateral, hard tissue landmark.

OriginZygomatic arch is a hard tissue cephalometric landmark of anatomic origin.

Chapter 6 Cephalom

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Figures 6.3A and D: (A) Porion on lateral cephalogram; (b) Magnified image showing porion on the lateral cephalogram; (C) Porion on graphic illustration; and (D) Magnified image of porion on graphic illustration

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Mastiodale

AbbreviationMs–Mastiodale is abbreviated using English alphabets and is expressed as capital or upper case M followed by lower case s, and is written continuously without any space between the alphabets.

Definition

According to Viken sassouniAccording to Viken Sassouni, the mastiodale is the lowest point on the contour of the mastoid process.8

TypeMastiodale (Figs 6.4A and B) is bilateral, cephalo metric landmark.

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OriginMastiodale is a hard tissue landmark of anatomic origin.

Tracing of Mastiodale on the Lateral Cephalogram

Trace the mastoid process, which is located between the temporal bone and cranial base region. The lowest point of the mastoid process in the P-A cephalogram is the point of mastiodale. As we learnt in anatomy, the mastoid process is not so visible in the childhood, but it increases in size with the age and readily visible in both P-A cephalogram and lateral cephalogram.

Figures 6.4A and B: (A) Mastiodale on lateral cephalogram; (b) Magnified image showing mastiodale on the lateral cephalogram

References 1. ArneBjork.Thefaceinprofiles-Sven.TandlakTidskr.1947;40:32-3. 2. DownsWB. Variations in facial relationships; Their significance in

treatmentandprognosis.AmJofOrthod.1948;34:812-39. 3. Higley LB. Cephalometric standards for children 4-8 years of age-Am J

of Orthod.1954;40:51-9. 4. Moyers RM. Handbook of Orthodontics. Year Book Medical Publishers,

Inc.1988;251-9. 5. Broadbent BH Sr. Bolton’s standards of dentofacial developmental

growth.TheCVMosbyCompany.1975;133-5. 6. Farkas LG. Anthropometry of the head and face in medicine—Elsevier

NorthHollandInc.1981;9-14. 7. Ricketts RR. Provocations and perceptions in cranio-facial orthopedics

–dental science and facial art. Rocky Mountain Inc.1989;797-803. 8. Viken Sassouni. Orthodontics in Dental Practice. The CV Mosby

Company.1971;330-7.

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7 Cephalometric landmarks related to sphenoid bone

The sphenoid bone (Fig. 7.1) is in the base of the skull, wedged (as its name implies) between the frontal, temporal and occipital bones. It has a central body paired greater and lesser wings of separating laterally from it and two pterygoid processes descending from the junction of the body of the greater wing.

Cephalometric Landmarks (Points) on Sphenoid BoneCephalometric landmarks seen on the sphenoid bone are as follows (Table 7.1):

Table 7.1: Cephalometric landmarks related to sphenoid bone



Dorsum of sella Sp Unilateral anatomic

Floor of sella Si Unilateral anatomic

Clinoidale Cl Bilateral anatomic

Spheno-occipitalsynchondrosis

SOS Unilateral anatomic

pterygoid point pt Bilateral anatomic

Sella S Unilateral anatomic

Sella entrance Se Unilateral anatomic

Sphenoethmoidal point Se Unilateral anatomic

Foramen spinosum point

Fsp Bilateral anatomic

pterygomaxillaryfissure

ptm Bilateral anatomic

Radiographic anatomy of Sphenoid Bone (Fig. 7.2)The frontal bone, ethmoidal bone and sphenoid bone meet at frontosphenoethmoidal suture, which radiographically appears as a radiolucent line. At the frontosphenoethmoidal suture, these are two radio-opaque lines, one vertical and the other horizontal. The vertical radio-opaque line represents the anterior border of the sphenoid body whereas horizontal line represents the planum sphenoidale, or the superior surface of the sphenoid body.

The vertical line terminates at the center of the pterygomaxillary fissure, which on lateral cephalogram appears as inverted teardrop radiolucent area bounded anteriorly by radio-opaque line of the maxillary tuberosity and posteriorly by the radio-opaque line of the anterior surface of the pterygoid process of the sphenoid bone. The sella turcica appears as elliptical shape radiolucent area surrounded medially radio-opaque line of medial surface of the sella and most inferiorly radio-opaque line of floor of sella anterosuperiorly curved radio-opaque line of anterior clenoid process and posterosuperiorly radio-opaque line of posterior border of the clenoid process.

Figure 7.1: sphenoid bone

Figure 7.2: radiographic anatomy of sphenoid bone

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The center of sella turcica is identified as sella abbreviated using English alphabet as upper case S and the mid-entrance point of the sella turcica is the sella-entrance (Se). Most inferior point of the curved radio-opaque line of floor of sella is identified as Si (Floor of sella ), and the most posterior point on the internal continuation of the sella turcica is identified as dorsum sellae. The most superior point on the contour of the anterior clenoid is identified as clenoidale (Cl).

Dorsum of Sella

abbreviationSp–Dorsum of sella is abbreviated using English alphabets and is expressed as capital letter or upper case S followed

by small letter or lower case p and is written continuously without any space between the alphabets.

DefinitionDorsum of sella is the most posterior point on the internal contour of the sella turcica or hypophyseal fossa or pituitary fossa.

according to Viken SassouniMost posterior point on the internal contour of the sella turcica.1

TypeDorsum of sella (Figs 7.3A to D) is a unilateral, hard tissue cephalometric landmark.

Figures 7.3A to D: (A) Dorsum of sella on lateral cephalogram; (b) Magnified image showing dorsum of sella on the lateral cephalogram; (C) Dorsum of sella on graphic illustration; (D) Magnified image of dorsum of sella on graphic illustration

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OriginDorsum of sella is an anatomic hard tissue cephalometric landmark.

Floor of Sella

abbreviationSi–Floor of sella is abbreviated using English alphabets and is expressed as capital letter or upper case S followed by small

letter or lower case i and is written continuously without any space between the alphabets.

DefinitionFloor of sella is the lower most point on the inner contour of the sella turcica or hypophyseal fossa or pituitary fossa.

TypeFloor of sella (Figs 7.4A to D) is a unilateral, hard tissue cephalometric landmark.

Figures 7.4A to D: (A) Floor of sella on lateral cephalogram; (b) Magnified image showing floor of sella on the lateral cephalogram; (C) Floor of sella on graphic illustration; (D) Magnified image of floor of sella on graphic illustration

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OriginFloor of sella is an anatomic hard tissue cephalometric landmark.

Clinoidale

abbreviationCl–Clinoidale is abbreviated using English alphabets and is expressed as capital C followed by lower case l.l

DefinitionClinoidale is the most superior point on the contour of the anterior clinoid.

according to Viken SassouniThe most superior point on the contour of the anterior clenoid.1

TypeClinoidale (Figs 7.5A to D) is a unilateral, hard tissue cephalometric landmark.

Figures 7.5A to D: (A) Clinoidale on lateral cephalogram; (b) Magnified image showing clinoidale on the lateral cephalogram; (C) Clinoidale on graphic illustration; (D) Magnified image of clinoidale on graphic illustration

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OriginClinoidale is a unilateral, anatomic, hard tissue cephalometric landmark.

Spheno-Occipital Synchondrosis

abbreviationSOS–Spheno-occipital synchondrosis abbreviated using English alphabets and is expressed as capital letter or upper case S, O and S and is written continuously without any space between the alphabets.

DefinitionOpisthion is the posterior edge of the foramen magnum.

according to arne BjorkAccording to Arne Bjork, the opisthion is the posterior margin of the occipital foramen.2

according to TM GraberAccording to TM Graber, the opisthion is the most posterior point on the posterior margin of the foramen magnum.3

TypeSpheno-occipital synchondrosis (Figs 7.6A to D) is a unilateral, hard tissue cephalometric landmark.

OriginSpheno-occipital synchondrosis is a unilateral, anatomic, hard tissue cephalometric landmark.

Figures 7.6A to D: (A) spheno-occipital synchondrosis on lateral cephalogram; (b) Magnified image showing spheno-occipital synchondrosis on the lateral cephalogram; (C) spheno-occipital synchondrosis on graphic illustration; (D) Magnified image of spheno-occipital synchondrosis on graphic illustration

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Significance (Ref to Chapter 20)The spheno-occipital synchondrosis is very important struc-ture in growth and development of the cranial base in the growing child.

Tracing Spheno-Occipital Synchondrosis on the Lateral CephalogramTracing of SOS is very easy, if it is before the ossification and very difficult if it is after the ossification.

Pterygoid Point

abbreviationPt–Pterygoid point abbreviated using English alphabets and is expressed as capital or upper case P followed by small or

lower case t, and is written continuously without any space between the alphabets.

DefinitionAccording to Robert M Ricketts, the pterygoid point is the lower lip of the foramen rotundum (represents the position of the sphenoid bone). Most posterior point on the outline of the pterygopalatine fossa.4

TypePterygoid point (Figs 7.7A to D) is a bilateral, hard tissue cephalometric landmark.

OriginPterygoid point is a bilateral, hard tissue cephalometric land-mark.

Figures 7.7A to D: (A) Pterygoid point on lateral cephalogram; (b) Magnified image showing pterygoid point on the lateral cephalogram; (C) Pterygoid point on graphic illustration; (D) Magnified image of pterygoid point on graphic illustration

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Tracing Pterygoid Point on the Lateral CephalogramTrace the pterygopalatine fossa point usually located immedi-ately behind the posterior part of the fossa.

Significance (Ref to Chapter 20)• Pterygoid point is a useful point for Rickett’s cephalometric

analysis.• Pterygoid point is the intersection border of the foramen

rotundum and the posterior wall of pterygopalatine fossa in the lateral cephalogram.

Sella

abbreviationS–Sella is abbreviated using English alphabets and is expressed as capital or upper case S.

Definition

Sella is the midpoint of sella turcica or hypophyseal fossa or pituitary fossa.

according to Robert E MoyersThe center of the hypophyseal fossa (sella turcica). It is selected by the eye since that producer as been shown to be as reliable as a constructed center.4

according to TM GraberThe center of pituitary fossa.3

according to B Holly BroadbentSella turcica (Turkish saddle): The landmark is the center of the sella as seen in the lateral radiograph and located by inspection.5

according to LB HigleyThe center of sella turcica: The midpoint of the sella turcica orbitrarily determined.6

according to Willam B DownsThe center of sella turcica: Located by inspection of the profile image of the fossa.7,8

according to arne BjorkThe center of sella turcica (the midpoint of the horizontal diameter).2

TypeSella (Figs 7.8A to D) is a unilateral, hard tissue cephalometric landmark.

OriginSella is a unilateral anatomic hard tissue cephalometric landmark point.

Tracing of Sella on the Lateral CephalogramThe pituitary fossa is round and bottle shaped hollow space, situated in the upper body of the sphenoid bone. This fossa contains pituitary gland. This fossa is bounded anterioly and posteriorly by anterior and posterior clinoid processes. Both anterior and posterior clinoid process appears as radio-opaque line on the lateral cephalogram. First trace the anterior and posterior cliniod process followed by inferior border of the pituitary fossa. Center point of the fossa is the point of sella.

Significance (Ref to Chapter 20)Sella is used as one of the reference points in the construction of angles and planes for the assessment of following:• Relationship of maxilla to cranial base is assessed using

SNA angle, S-N-Pr angle and saddle angle (N-S-Ar).• Relationship of mandible to cranial base is assessed using

SNB angle and S-N-Id angle.• Relationship of anterior and posterior cranial base assessed

using N-S-Ar.

Sella Entrance

abbreviation

Se–Sella entrance is abbreviated using English alphabets and is expressed as capital letter or upper case S followed by small letter or lower case e and is written continuously without any space between the alphabets.

Definition

Sella entrance is the mid entrance point of sella turcica or hypophyseal fossa or pituitary fossa.

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Figures 7.8A and B: (A) sella on lateral cephalogram; (b) Magnified image showing sella on the lateral cephalogram; (C) sella on graphic illustration; (D) Magnified image of sella on graphic illustration

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TypeSella entrance (Figs 7.9A to D) is a unilateral, hard tissue cephalometric landmark.

OriginSella entrance is a constructed, hard tissue cephalometric landmark.

Sphenoethmoidal Point

abbreviationSE–Sphenoethmoidal point (Figs 7.10A to D) is abbreviated using English alphabets and is expressed as upper case S,

E and written continuously without any space between the alphabets.

Definition

according to Robert E MoyersThe intersection of the shadows of the greater wing of the sphenoid and the cranial floor as seen in the lateral cephalogram.4

according to SN Bhatia and BC LeightonThe point of intersection between the greater wings of the sphenoid and the anterior cranial base.9

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Figures 7.10A and B: (A) sphenoethmoidal point on lateral cephalogram; (b) Magnified image showing sphenoethmoidal point on the lateral cephalogram

Figures 7.9A to D: (A) sella entrance on lateral cephalogram; (b) Magnified image showing sella entrance on the lateral cephalogram; (C) sella entrance on graphic illustration; (D) Magnified image of sella entrance on graphic illustration

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TypeSphenoethmoidal point is a unilateral, hard tissue cephalomet-ric landmark.

Pterygomaxillary Fissure

abbreviationPtm–Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P followed by small or lower case t and m, written continuously without any space between the alphabets.

PTM–According to Robert M Moyers, Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P followed by capital or upper case T and M, written continuously without any space between the alphabets.

PTMS–According to Michael L Riolo, Pterygomaxillary fissure is abbreviated using English alphabets and is expressed as capital or upper case P,T,M,S, written continuously without any space between the alphabets.

DefinitionPterygomaxillary fissure (Figs 7.11A to D) is a bilateral tear drop shaped area of radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla; the landmark is taken where the two edges, front and back, appear to merge inferiorly.

according to TM Graber According to TM Graber, the pterygomaxillary fissure is an oval-looped radiolucency resulting from the fissure between

the anterior margin of the pterygoid process of the sphenoid bone and the profile outline of the posterior surface of the maxilla.

according to Robert M MoyersAccording to Robert M Moyers, the pterygomaxillary fissure is tear drop shaped radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla; the landmark itself is at the most inferior confluences of the curvatures.

according to Clifton T ForcebergAccording to Clifton T Forceberg, Pterygomaxillary fissure is the most medial and posterior point of each pterygomaxillary fissure. The ptm line connects right and left ptm points. The ptm access is the perpendicular bisector of the ptm line.

according to Holly Broadbent

Inverted, elongated, tear drop-shaped area formed by the divergence of the maxilla from the pterygoid process of the sphenoid. The posterior nasal spine and staphylion are gener-ally located beneath the lower pointed end of this area.

according to LB HigleyJunction of the Frankfort plane and a line perpendicular to it from the pterygomaxillary fissure.

TypePterygomaxillary fissure is an anatomic, bilateral, hard tissue cephalometric landmark.

Figures 7.10C and D: (C) sphenoethmoidal point on graphic illustration; (D) Magnified image of sphenoethmoidal point on graphic illustration

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Significance (Ref to Chapter 20)Pterygomaxillary fissure is used as one of the reference point in Cox cephalometric analysis and is used to assess the posterior limit of the maxilla.

References 1. Viken Sassouni. Orthodontics in dental practice. The CV Mosby

Company. 1971;330-7. 2. Arne Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3. 3. Graber TM. New horizons in case analysis-clinical cephalometrics.

Am J of Ortho.1952;38:603-24.

4. Robert R. Ricketts–Provocations and perceptions in cranio-facial orthopedics–dental science and facial art. Rocky Mountain Inc. 1989; 797-803.

5. Moyers RM. Handbook of Orthodontics–Year Book Medical Publishers, Inc. 1988;251-9.

6. Holley Broadbent B, Sr. Bolton’s standards of dentofacial develop-mental growth. The CV Mosby Company. 1975;133-5.

7. Higley LB. Cephalometric standards for children 4-8 years of age.Am J of Ortho. 1954;40:51-9.

8. Downs WB. Variations in facial relationships. Their significance in treatment and prognosis. Am J of Ortho.1948;34:812-39.

9. Bhatia SN, Leighton BC. A manual of facial growth–Oxford University. 1993;10-5.

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8 Cephalometric Landmarks Related to Occipital Bone

The occipital bone (Fig. 8.1) forming much of the back and base of the cranium and is trapezoidal and concave internally.

Cephalometric Landmarks (Points) on Occipital BoneCephalometric landmarks seen on the occipital bone are of anatomic origin and are as follows (Table 8.1):

Table 8.1: Cephalometric landmarks related to occipital bone


Basion Ba Unilateral Anatomic

Opisthion Op Unilateral Anatomic

Bolton’s point Bo Unilateral Anatomic

Spheno-occipital synchondrosis

SOS Unilateral Anatomic

Radiographic Anatomy of Occipital Bone (Fig. 8.2)The occipital bone joins the parietal bone at lambdoid suture, which on lateral cephalogram appears as a radiolucent line.

The inner and outer cortical plates of the occipital bone appear as two radio-opaque lines, which descend parallely and meet together at formen magnum, where the hard tissue cephalometric point opisthion is identified. The exocranial and endocranial surfaces of the occipital bone appear as two radio-opaque lines, the point where these two surfaces meet is the point of basion, which is an important hard tissue cephalometric landmark.

Basion

AbbreviationBa–Basion is abbreviated using English alphabets and is denoted as capital letter or upper case B followed by small letter or lower case a and is written continuously without any space between the alphabets.

DefinitionBasion is the median point of the anterior margin of the foramen magnum can be located by following the images of the slope the inferior border of the basilar part of the occipital bone to its posterior limit.

Figure 8.1: Occipital bone Figure 8.2: Radiographic anatomy of occipital bone

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According to Robert M RickettsPoint at the center of the anterior border of the foramen magnum at the base of the occipital bone.1

According to TM GraberThe most inferior point on the anterior margin of the foramen magnum in the midsagittal plane.2

According to Robert E MoyersThe most inferior posterior point in the sagittal plane on the anterior rim of the foramen magnum.3

According to Arne BjorkNormal projection of the anterior border of the occipital foramen (endobasion) on the occipital foramen line.4

According to Clifton T ForsbergThe most anterior point relative to the interspinosum line, on the border of the foramen magnum.5

TypeBasion (Figs 8.3A to D) is a unilateral, hard tissue cephalo-metric landmark.

OriginBasion is a anatomic hard tissue cephalometric landmark.

Tracing Basion on the Lateral Cephalogram• To identify basion on the lateral cephalogram, following

structures need to be traced.• Trace from the posterior clinoid process, down the upper part

of the clivus, and past the region of the spheno-occipital syn-chondrosis to the anterior margin of the foramen magnum.

Figures 8.3A to D: (A) Basion on lateral cephalogram; (B) Magnified image showing basion on the lateral cephalogram; (C) Basion on graphic illustration; (D) Magnified image of basion on graphic illustration

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• Trace the cranial aspect of the greater wing of the sphenoid one, the inferior, ectocranial aspect of the base of the occipital bone, and the anterior margin of the foramen magnum. These are separate lines and should not be drawn a one continuous line.

• Trace carefully from the base of the occipital bone to the compact bone of the occipital condyles. The anterior margins of the occipital condyle and basion are radio-opaque on the lateral cephalogram and should be differentiated. Basion is usually behind the anterior part of the occipital condyle.

Opisthion

AbbreviationOp–Opisthion is abbreviated using English alphabets and is expressed as capital letter or upper case O followed by small letter or lower case p and is written continuously without any space between the alphabets.

DefinitionOpisthion is the posterior edge of the foramen magnum.

According to Arne BjorkPosterior margin of the occipital foramen.4

According to TM GraberThe most posterior point on the posterior margin of the foramen magnum.2

According to Clifton T ForsbergThe most posterior point, relative to the inter-spinosum line on the border of the foramen magnum.5

TypeOpisthion (Figs 8.4A to D) is a unilateral, hard tissue cephalometric landmark.

OriginOpisthion is an anatomic, hard tissue cephalometric landmark.

Tracing Opisthion on Lateral CephalogramTrace both the outer, ectocranial surface of the external occipital protuberance and the inner, endocranial surface of the occipital bone. Follow the surfaces anteroinferiorly until the two lines merge as the radio-opaque point, which is opisthion.

Bolton’s Point

AbbreviationBo–Bolton’s point is abbreviated using English alphabets and is expressed as capital letter or upper case B followed by small letter or lower case o and is written continuously without any space between the alphabets.

DefinitionBolton’s point is the highest point in the upward curvature of the retrocondylar fossa.

Figures 8.4A and B: (A) Opisthion on lateral cephalogram; (B) Magnified image showing opisthion on the lateral cephalogram

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According to B Holly BroadbentPoint in space, about the center of foramen magnum, that is located on the lateral cephalometric radiograph by the highest point in the profile image of the postcondylar notches of the occipital bone.5

According to Arne BjorkThe deepest point of the notch in the shadow behind condylus occipitalis.3

According to William B DownsThe highest point on the concavity behind the occipital condyles.6

According to Viken SassouniHighest point in the upward curvature of the retrocondylar fossa. In uncertain cases it may be located as the midpoint between opisthion (Op), and basion (Ba); in other words, at the center of foramen magnum.7

According to TM GraberThe most superior point in the uppet curvature of the retrocondylar fossa. It is just posterior to the occipital condyle.2

TypeBolton’s point (Figs 8.5A to D) is a unilateral, hard tissue cephalometric landmark.

Figures 8.5A and B: (A) Bolton’s point on lateral cephalogram; (B) Magnified image showing Bolton’s point on the lateral cephalogram

Figures 8.4C and D: (C) Opisthion on graphic illustration; (D) Magnified image of opisthion on graphic illustration

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OriginBolton’s point is an anatomic hard tissue cephalometric landmark/point.

Tracing Bolton’s Point on the Lateral CephalogramBolton’s point is the midway between the point basion and opisthion. Trace the basion and opisthion and bisect the distance between these two points to establish the Bolton’s point.

Spheno-Occipital Synchondrosis

AbbreviationSOS–Spheno-occipital synchondrosis abbreviated using English alphabets and is expressed as capital S, O and S

and is written continuously without any space between the alphabets.

TypeSpheno-occpital synchondrosis (Figs 8.6A to D) is a unilateral, hard tissue cephalometric landmark.

OriginSpheno-occipital synchondrosis is an anatomic hard tissue cephalometric landmarks.

Tracing Spheno-Occipital Synchondrosis on the Lateral CephalogramTracing of SOS is very easy, if it is before the ossification and very difficult, if it is after the ossification.

Figures 8.6A and B: Spheno-occipital synchondrosis on lateral cephalogram; (B) Magnified image showing spheno-occipital synchondrosis on the lateral cephalogram

Figures 8.5C and D: (C) Bolton’s point on graphic illustration: (D) Magnified image of Bolton’s point on graphic illustration

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Significance (Ref to Chapter 20)The spheno-occipital synchondrosis is very important struc ture in growth and development of the cranial base in the growing child.

References 1. Ricketts RR. Provocations and perceptions in cranio-facial orthopedics

–dental science and facial art. Rocky Mountain Inc. 1989;797-803. 2. Graber TM. New horizons in case analysis-clinical cephalometrics. Am

J of Ortho. 1952;38:603-24.

3. Moyers RM. Handbook of Orthodontics. Year Book Medical Publishers, Inc. 1988;251-9.

4. Arne Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3. 5. Clifton T Forsberg. Diagnosis and treatment planning of skeletal

asymmetry with the sub-mental vertical radiograph. Am J of Ortho. 1984;85:224-37.

6. Downs WB. Variations in facial relationships; Their significance in treatment and prognosis. Am J of Ortho.1948;34:812-39.

7. Viken Sassouni. Orthodontics in dental practice. The CV Mosby Company. 1971;330-7.

Figures 8.6C and D: (C) Spheno-occipital synchondrosis on graphic illustration; (D) Magnified image of spheno-occipital synchondrosis on graphic illustration

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9 Cephalometric landmarks related to Zygomatic bone

Each zygomatic bone (Figs 9.1A and B) consists of a diamond-shaped body and following four processes:• Frontal process articulates with the frontal bone at

zygomaticofrontal suture forming the lateral wall of the orbit.

• Temporal process articulates with the zygomatic process of the temporal bone, forming the zygomatic arch.

• Maxillary process articulates with the zygomatic process of the maxilla at the zygomaticomaxillary suture, forming theinfraorbitalrimandtheorbitalfloor.

• Jugular process articulates the maxilla at the lateral wall of the maxillary sinus.

Radiographic Anatomy of Zygomatic BoneThe frontal process of the zygomatic bone appears as two radio-opaque lines on the lateral cephalogram, one anterior and the other posterior. The anterior line is curved line representing the anterior border of the lateral wall of the orbit. The posterior line is a vertical line that extends downward from the junction with the cribriform plate and merges with the posterior border of the zygomatic process of the maxilla. Between the inferior parts of the two lines, there is another horizontal radio-opaque line, which represents the maxillary

process of the zygomatic bone. This line extends posteriorly and merges with the horizontal part of the zygomatic process of the maxilla.

Cephalometric landmarks (Points) on Zygomatic Bone Cephalometric landmarks seen on the zygomatic bone are of anatomic origin and are as follows (Table 9.1):

Table 9.1: Cephalometric landmarks related to zygomatic bone


Orbitale Or Bilateral anatomic

temporale te Bilateral anatomic

Orbitale

AbbreviationOr–Orbitale is abbreviated using English alphabets and is denoted as capital letter or upper case O followed by small letter or lower case r and is written continuously without any space between the alphabets.

A B

Figures 9.1A and B: Zygomatic bone

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DefinitionOrbitale is the lowest point in the inferior margin of the orbit, midpoint between right and left images.

According to William B Downs Orbitale is the lowest point on the left infraorbital margin.1

According to TM Graber Orbitale is the most inferior point on the lower border of the left orbit.2

According to B Holly Broadbent Orbitale is the left orbital point used in conjunction with the poria to orient the skull on the Frankfort horizontal plane.3

According to leslie G FarkasOrbitale is the lowest point on the lower margin of each orbit.It is identified by palpation and is identical to thebony orbitale.4

According to Robert E MoyersIn the lateral cephalogram, the outlines of the orbital rims overlap. Usually, the lowest point on the averaged outline is used for the construction of Frankfort plane.5

TypeOrbitale (Figs 9.2A to D) is a bilateral, hard tissue cephalo metric.l

OriginOrbitale is an anatomic hard tissue cephalometric landmarks.

Figures 9.2A to D: (A) Orbitale on lateral cephalogram; (b) Magnified image showing orbitale on the lateral cephalogram; (C) Orbitale on graphic illustration; (D) Magnified image of orbitale on graphic illustration

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Tracing of Orbitale on lateral Cephalogram Normally, right and left infra-orbital margins are superimposed on the lateral cephalogram, then they reveal radio-opaque line on the lateral cephalogram, when patient is positioned accurately on the cephalostat during the radiographic taking procedure. If the patient is inaccurately positioned then in such cases, the infra-orbital margins appear as two different radio-opaque lineson the lateralcephalogrammakingdifficult to identifythepoint.Insuchcases, theorbitaleis identifiedasthemidpoint of right and left infra-orbital margins.

Significance (Ref to Chapter 20)Orbitale is used as one of the reference points in the construction of Frankfort horizontal plane and is used for the assessment of horizontal growth pattern using following angles:

• FH-Mandibular plane angle (Go- Me)• FH- Palatal plane angle ( ANS-PNS)• FH-Occlusal plane ( APOcc – PPOcc).

Temporale

AbbreviationTe–Temporale is abbreviated using English alphabets and is expressed as capital or upper case T followed by small letters or lower case e and is written continuously without any space between the alphabets.

DefinitionTemporale (Figs 9.3A to D) is the intersection of the shadows of the ethmoid and the anterior wall of the infratemporal fossa.

Figures 9.3A to D: (A) Temporale on lateral cephalogram; (b) Magnified image showing temporale on the lateral cephalogram; (C) Temporale on graphic illustration; (D) Magnified image of temporale on graphic illustration

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According to Viken Sassouni Intersection of the shadows of the ethmoid and anterior wall of the infra-temporal fossa.6

TypeTemporale is a bilateral, hard tissue cephalometric landmark.

OriginTemporale is an anatomic hard tissue cephalometric landmark.

References 1. DownsWB. Variations in facial relationships; Their significance in

treatment and prognosis. Am J of Ortho. 1948;34:812-39. 2. Graber TM. New horizons in case analysis-clinical cephalometrics. Am

J of Ortho. 1952;38:603-24. 3. Broadbent BH, Sr. Bolton’s standards of dentofacial developmental

growth. The CV Mosby Company. 1975; 133-5. 4. Farkas LG. Anthropometry of the head and face in medicine. Elsevier

North Holland Inc. 1981;9-14. 5. Moyers RM. Handbook of Orthodontics—Yearbook Medical Publishers

Inc. 1988;251-9. 6. Viken Sassouni. Orthodontics in dental practice. The CV Mosby

Company. 1971;330-7.

Section4Cephalometric Landmarks Related to Facial Bones

and Dentition

Cephalometric Landmarks Related to Maxilla CephalometricLandmarksRelatedtoDentition Cephalometric Landmarks Related to Mandible

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10 Cephalometric Landmarks Related to Maxilla

The maxilla (Fig. 10.1) consists of a large hollow body that houses the maxillary sinus and the four prominent processes.• The frontal process• The zygomatic process• The palatine process• The alveolar process.

Cephalometric Landmarks (Points) on MaxillaCephalometric landmarks seen on the maxilla are as follows (Table 10.1):

Table 10.1: Cephalometric landmarks related to maxilla


anterior nasal spine aNS Unilateral anatomic

point a a Unilateral anatomic

anterior point of maxilla apMax Unilateral anatomic

prosthion pr Unilateral anatomic

posterior nasal spine pNS Unilateral anatomic

Pterygomaxillaryfissure • Ptm• PTM• PTMS

Bilateral anatomic

Key ridge KR Unilateral anatomic

Orbitale Or Bilateral anatomic

Anterior Nasal Spine

AbbreviationANS–Anterior nasal spine is abbreviated using English alphabets and is expressed as capital or upper case A, N and S, written continuously without any space between the alphabets.

DefinitionAnterior nasal spine (Figs 10.2A to D) is the tip of bony anterior nasal spine in the midline or median plane.

According to Viken SassouniThemostanteriorpointofthenasalfloortipofpre-maxillaonmid-sagittalplane.1

According to B Holly BroadbentSharp median process formed by the forward prolongation of the anterior aperture of the nose.2

According to TM GraberThetipoftheanteriornasalspineasseenontheX-rayfilminnorma lateralis.3

According to Robert E MoyersThe most anterior point on the maxilla at the level of the palate.TheANSisoflimiteduseforanalysisintheposterior-

Figure 10.1: Maxillary bone

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Figures 10.2A to D: (A) Anterior nasal spine on lateral cephalogram; (B) Magnified image showing anterior nasal spine on the lateral cephalogram; (C) Anterior nasal spine on graphic illustration; and (D) Magnified image of Anterior nasal spine on graphic illustration

anterior projection as the actual spine often cannot be seen and its location varies considerably according to radiographic exposure.4

TypeAnterior nasal spine is a unilateral, hard tissue cephalometric landmark.

OriginAnterior nasal spine is an anatomic hard tissue cephalometric landmark.

Tracing of Anterior Nasal Spine on Lateral CephalogramThere is an individual variation exists in length and width of ANS. In some individuals ANS are long and thin; while in other are short and thick.

Radiographic Appearance• ANS appears slightly posterior to the anatomic spine.• IncaseswiththinANS: In such cases, on the cephalogram,

ANS will be unclear because it can superimpose by nasal cartilage.

• IncaseswiththickANS: In such cases, on the cephalogram, ANS is clear and will be ease in tracing.

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Significance (Ref to Chapter 20)Anterior nasal spine is used as one of the reference points in the construction of occlusal plane and is used for the assessment of horizontal growth pattern using FH-palatalplaneangle(ANS-PNS).

Point A

AbbreviationPoint A: PointAisabbreviatedusingEnglishalphabetsandisexpressed as A itself.

DefinitionPointA(Figs 10.3A to D) is the deepest point on the curved bony outline between the anterior nasal spine (ANS) andprosthion(Pr).

According to Willian B DownsThe deepest midline point on the premaxilla between the anterior nasal spine and prosthion.5

According to Robert M RickettsDeepest point on the curve of the bone between the anterior nasal spine and dental alveolus. Also termed SS or subspinale (belowthespine).6

Figures 10.3A to D: (A) Point A on lateral cephalogram; (B) Magnified image showing point A on the lateral cephalogram; (C) Point A on graphic illustration; and (D) Magnified image of point A on graphic illustration

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According to Viken SassouniDeepest point on midsagittal plane between ANS and prosthion, mesially around the level of and anterior to the apex of the upper central incisors.1

According to TM GraberThemostposteriorpointonthepre-maxillaaboveprosthionand immediately lateral to the contour of projection of the anterior nasal spine. It is the junction of the alveolar and basal of the maxilla.3

According to Alex Jacobson and W CaufieldUsing a line perpendicular to FH locate the most posterior point in the concavity between ANS and maxillary alveolar process.7

OrThe most posterior midline point in the concavity between the ANS and prosthion (The most inferior point on the alveolar boneoverlyingthemaxillarycentralincisor).

According to Robert E MoyersThemostposteriorpointonthecurvebetweenANSandPR“A” point usually is found approximately 2 mm anterior to the apices of the maxillary central incisor roots. A is not an anatomic point, of course.4

According to JR JarabakMaxillary denture base, point A is 2 mm labial to the apices of the central incisors.8

TypePointAisaunilateral,hardtissuecephalometriclandmark.

OriginPointAisananatomichardtissuecephalometriclandmark.

Tracing Procedure for Point A• First trace the palatal bone, the anterior nasal spine, the

marginal bone of the alveolar process and the anterior facial surface of the alveolar process.

• Thereafter, trace the outline of maxillary central incisor which includes tracing of incisal edge, apex of the root outer surface of the crown and root of maxillary central incisor.

• Note:The most important factor which helps in location of point A is that it is at almost the same height as the apex of the incisor.

• To establish A point, draw a line between ANS and prosthion.ThendrawalineparalleltotheANS–Prline,tangenttothedeepestpointbetweenANSandPr.Thisispoint A.

Significance (Ref to Chapter 20)PointAisusedasoneofthereferencepointsintheconstructionof angles and planes for the assessment of the following:• Relationship of maxilla to cranial base is assessed using

SNA angle.• Maxillo-mandibular relationship with anterior cranial

base is assessed using ANB angle.• Inclination upper incisors are assessed usingNA-Upper

incisorangularandNA-Upperincisorlinear.• Point A is useful indicator of the anteroposterior

relationship between the basal bone of the maxilla and the malocclusion.

• In Mc Namara cephalometric analysis, anteroposterior orientation of the maxilla to the cranial base is assessed by the linear distance between nasion perpendicular and point A. An anterior position of point A is a positive value and a posterior position of point A is a negative value.

• MidfaciallengthismeasuredfromcondyliontoPointAin McNamara analysis.

• In Mc Namara cephalometric analysis, method of determining of position of maxillary incisor relative to pointA.DrawverticallinethroughthenasioncalledNP(Nasion perpendicular) and A vertical line constructedthrough the point A parallel to the Nasion perpendicular line called the parallel to nasion perpendicular through pointA (PNP).Theanteroposteriordistance from maxi-llary incisor to point A.

• In Mc Namara cephalometric analysis, to determine the anteroposterior position of the mandibular incisors, the distance is measured between the edge of the incisor and alinedrawnfrompointAtoPog.Inawell-balancedface,this distance should be 13 mm.

Prosthion

AbbreviationPr: Prosthion is abbreviated usingEnglish alphabets and isexpressedascapitalletteroruppercasePfollowedbysmallletter or lower case r and is written continuously without any space between the alphabets.

DefinitionProsthion(Figs 10.4A to D) is the lowermost anterior point ofalveolarprocessofpre-maxillainthemidlinebetweentwomaxillary central incisors.

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According to Arne BjorkThe transition point between the crown of the most prominent medial maxillary incisor and the alveolar projection.9

According to TM GraberThe point of the maxillary alveolar process in the midline that projects most anteriorly.3

According to Robert E MoyersThe most anterior inferior point on the maxillary alveolar process usually found near the cementoenamel junction of the maxillary central incisor.4

Type

Prosthionisaunilateral,hardtissuecephalometriclandmark.

Origin

Prosthionisananatomichardtissuecephalometriclandmark.


Prosthion is used as one of the reference points in theconstruction of angles for the assessment of relationship of maxillaskeletalbasetocranialbaseusingS-N-Prangle.

Figures 10.4A to D: (A) Prosthion on lateral cephalogram; (B) Magnified image showing prosthion on the lateral cephalogram; (C) Prosthion on graphic illustration; and (D) Magnified image of prosthion on graphic illustration

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Posterior Nasal Spine

AbbreviationPNS: Posterior Nasal Spine is abbreviated using EnglishalphabetsandisexpressedascapitalletteroruppercaseP,Nand S and is written continuously without any space between the alphabets.

DefinitionPosteriorNasalSpine(Figs 10.5A to D ) is the intersection of a continuation of the anterior wall of the pterygopalatine fossa andthefloorofthenose.

According to Michael L RioloThe most posterior point at the sagittal plane on the bony hard palate.10

According to TM Graber

The bony posterior projection of the horizontal portion of the palatine bone at the midline.3

According to B Holly Broadbent

Process formedby theunitedprojectingmedial endsof theposterior borders of the two palatine bones.2

According to Viken Sassouni

Most posterior point on the contour of the bony palate.1

According to Alex Jacobson and W Caufield

Using a line perpendicular to FH, locate PNS at the mostposterior aspect of the palatine bone.7

Figures 10.5A to D: (A) Posterior nasal spine on lateral cephalogram; (B) Magnified image showing posterior nasal spine on the lateral cephalogram; (C) Posterior nasal spine on graphic illustration; and (D) Magnified image of posterior nasal spine on graphic illustration

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According to Robert M RickettsMidpoint of the base of the palatine bone at the posterior margin of the hard palate.6

TypePosteriornasalspineisaunilateral,hardtissuecephalometriclandmark.

OriginPosteriornasalspineisananatomichardtissuecephalometriclandmark.

Tracing of Posterior Nasal Spine on the Lateral Cephalogram• LikeANS,PNSalsohasvariationinlengthandwidth.• PNSisdifficult to traceon thecephalogramwhen there

isuneruptedteeth,inthesecasesthePNScanbelocatedbetweenthefloorofnasalcavityandtheinferiorsurfaceof the palatine bone.

• Usually,itisfoundthatPNSislocatedbelowthePtm.

Significance (Ref to Chapter 20)Posterior nasal spine is used as one of the reference points in the construction of occlusal plane and is used for the assessment of horizontal growth pattern using FH-Palatalplaneangle(ANS-PNS).


AbbreviationPtm: Pterygomaxillary fissure is abbreviated using EnglishalphabetsandisexpressedascapitaloruppercasePfollowedby small or lower case t and m, written continuously without any space between the alphabets.PTM:AccordingtoRobert.M.Moyers,Pterygomaxillaryfissureis abbreviated using English alphabets and is expressed as capital or upper case P followed by capital or upper case T andM,written continuously without any space between the alphabets.4

PTMS: According to Michael L Riolo, PterygomaxillaryfissureisabbreviatedusingEnglishalphabetsandisexpressedas capital or upper case P, T, M, S, written continuouslywithout any space between the alphabets.9

DefinitionPterygomaxillaryfissure(Figs 10.6A to D) is a bilateral tear drop shaped area of radiolucency, the anterior shadow of

which represents the posterior surface of the tuberosity of the maxilla; the landmark is taken where the two edges, front and back appear to merge inferiorly.

According to TM GraberAccording toTMGraber, thepterygomaxillaryfissure isanoval-loopedradiolucencyresultingfromthefissurebetweenthe anterior margin of the pterygoid process of the sphenoid bone and the profile outline of the posterior surface of themaxilla.3

According to Robert M MoyersAccordingtoRobertMMoyers,thepterygomaxillaryfissureis tear drop shaped radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla;thelandmarkitselfisatthemostinferiorconfluencesof the curvatures.4

According to Clifton T ForsbergAccordingtoCliftonTForsberg,pterygomaxillaryfissureisthe most medial and posterior point of each pterygomaxillary fissure.ThePtmlineconnectsrightandleftPtm points. The Ptm access is the perpendicular bisector of the Ptm line.11

According to Holly BroadbentInverted, elongated, tear drop-shaped area formed by thedivergence of the maxilla from the pterygoid process of the sphenoid. The posterior nasal spine and staphylion are generally located beneath the lower pointed end of this area.2

According to LB HigleyJunction of the Frankfort plane and a line perpendicular to it fromthepterygomaxillaryfissure.12

TypePterygomaxillary fissure is bilateral, hard tissue cephalo-metric landmark.

OriginPterygomaxillaryfissureisananatomichardtissuecephalo-metric landmark.

Significance (Ref to Chapter 20)Pterygomaxillary fissure is used as one of the referencepoints in Cox cephalometric analysis and is used to assess the posterior limit of the maxilla.

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Key Ridge

Abbreviation

KR: Key ridge is abbreviated using English alphabets and is expressed as capital or upper case K, and R, and is written continuously without any space between the alphabets.

DefinitionThe key ridge (Figs 10.7A to D) is the lowermost point on the contour shadow of the anterior wall of the infratemporal fossa.

According to Viken SassouniLowermost point on the contour of the shadow of the anterior wall of the infratemporal fossa.1

According to Robert E MoyersThe lowest point on the outline of the zygoma.4

According to TM GraberThe most inferior point on the zygomatic ridge.3

TypeKey ridge is a bilateral, hard tissue cephalometric landmark.

Figures 10.6A to D: (A) Pterygomaxillary fissure on lateral cephalogram; (B) Magnified image showing pterygomaxillary fissure on the lateral cephalogram; (C) Pterygomaxillary fissure on graphic illustration; and (D) Magnified image of pterygomaxillary fissure on graphic illustration

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OriginKey ridge is an anatomic hard tissue cephalometric landmark.

Orbitale

AbbreviationOr:Orbitale is abbreviated using English alphabets and is ex-pressed as capital or upper case O, followed by small or lower case r and both alphabets are written continuously without any space between them.

Definition

According to Arne BjorkThe deepest point on the infraorbital margin.The midpoint, or is used where double projection gives rise to two points, or 1 and or 2.9

According to William B DownsThelowestpointontheleftinfra-orbitalmargin.5

According to TM GraberThe most inferior point on the lower border of the left orbit.3

Figures 10.7A to D: (A) key ridge on lateral cephalogram; (B) Magnified image showing key ridge on the lateral cephalogram; (C) key ridge on graphic illustration; and (D) Magnified image of key ridge on graphic illustration

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According to B Holly BroadbentThe left orbital point is used in conjunction with poria to orient the skull on the Frankfort horizontal plane.2

Leslie G FarkasOrbitale is the lowest point on the lower margin of the each orbit. Itisidentifiedbypalpationandisidenticaltothebonyorbitale.13

According to Robert E MoyersIn the lateral cephalogram, the outlines of the orbital rims overlap. Usually, the lowest point on the averaged outline is used for the construction of Frankfort plane.4

TypeOrbitale is a bilateral (Figs 10.8A to D), anatomic, hard tissue cephalometric landmark.

OriginOrbitale is an anatomic hard tissue cephalometric landmark.


Orbitale is used as one of the reference points in the construction of angles and planes for the assessment of following:• Growth pattern is assessed using FH plane-Mandibular

plane.

Figures 10.8A to D: (A) Orbitale on lateral cephalogram; (B) Magnified image showing orbitale on the lateral cephalogram; (C) Orbitale on graphic illustration; and (D) Magnified image of orbitale on graphic illustration

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• Upper incisor torque is assessed using FH-long axis ofupper incisor.

Tracing of Orbitale on the Lateral CephalogramNormally,rightandleftinfra-orbitalmarginsaresuperimposedonthelateralcephalogram,andthentheyrevealradio-opaqueline on the lateral cephalogram, when patient is positioned accurately on the cephalostat during the radiographic taking procedure. If the patient is inaccurately positioned then in such cases, theinfra-orbitalmarginsappearastwodifferentradio-opaquelineson the lateralcephalogrammakingdifficult to identifythepoint.Insuchcases,theorbitaleisidentifiedasthemid-pointofrightandleftinfra-orbitalmargins.

References1. Viken Sassuoni. Orthodontics in dental practice. The CV Mosby

company.1971;330-7.

2. Broadbent BH Sr. Bolton’s standards of dentofacial developmental growth.TheCVMosbyCompany.1975;133-5.

3. Graber TM. New horizons in case analysis. Clinical cephalometrics. AmJofOrtho.1952;38:603-24.

4. Moyers RM. Handbook of Orthodontics.Year book medical publishers, Inc.1988;251-9.

5. Downs WB. Variations in facial relationships. Their significance intreatmentandprognosis.AmJofOrtho.1948;34:812-39.

6. RickettsRM.Provocationsandperceptionsincranio-facialorthopedics.Dentalscienceandfacialart.RockyMountains,Inc.1989;797-803.

7. AlexJacobson,CaufieldW.Introductiontoradiographiccephalometry.LeaandFebiger.1985;37-40.

8. Jarabak JR. Technique and treatment with light wire appliance. The CV Mosbycompany.1963;132-3.

9. ArneBjork.Thefaceinprofiles.Sven.TandlakTidskr.1947;40:32-3.10. Riolo ML. An atlas of craniofacial growth. Cephalometric standards from

the university school growth study, the university of Michigan.Center for humangrowthanddevelopment.TheUniversityofMichigan.1974;12-21.

11. Forsberg CT. Diagnosis and treatment planning of skeletal asymmetry withsubmental.Verticalradiograph.AmJofOrtho.1984;85:224-37.

12. HigleyLB.Cephalometricstandardsforchildren4-8yearsofage.AmJofOrtho.1954;40:51-9.

13. Farkas LG. Anthropometry of the head and face in medicine. Elsevier northHolland,Inc.1981;9-14.

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11 Cephalometric Landmarks Related to Dentition

Dental occlusion undergoes significant changes from birth until adulthood and beyond. This continuation of changes in the dental relationship during various stages of the dentition can be divided into four stages: 1. Gum pad stage—0–6 months 2. Deciduous dentition—6 months–6 years 3. Mixed dentition—6–12 years 4. Permanent dentition—12 years and beyond.

Gum Pad Stage (0–6 Months)Usually jaws are devoid of teeth at birth. Gum pad stage extends from birth up to the eruption of first primary tooth usually the lower central incisors at around 6 months of age. The gum pads are pink in color and firm in consistency. The maxillary gum pad is U/square shaped, and the mandibular gum pad is horse-shoe shaped. The gum pads develop in two portions—buccal and lingual portions which are separated by the dental groove. The gum pads in both the arches show certain elevations and grooves that outline the portion of the various primary teeth that are still developing in the alveolar ridges. These grooves are called as transverse grooves. The prominent transverse groove separating canine and first deciduous molar segments in both the arches is called the lateral sulcus. The lateral sulcii are often used to judge the inter-arch relationship at a very early stage. The gingival groove separates the maxillary and mandibular gum pads from the palate and floor of the mouth respectively.

Deciduous Dentition Stage (6 Months to 6 Years)The deciduous dentition stage spans from the time of eruption of primary teeth until the eruption of the first permanent tooth around 6 years of age.

Eruption Chronology of Primary TeethEruption of the primary teeth begins by 6 months of age when primary mandibular incisors erupt into oral cavity. Eruption

of all the primary teeth is usually complete by two and half years by which age, the deciduous dentition is in full function. Root formation of primary teeth is usually completed by three years of age. Although considerable variation is seen in the eruption timing of deciduous teeth, there appears to be no significant gender differences. The chronology of primary teeth is presented in the Table 11.1. The sequence of eruption of primary teeth may also show some variation. However, in most of the cases, the lower central incisors are the first teeth to erupt, followed by the upper central incisors. Usually the lateral incisor, first molar and canine tend to erupt earlier in maxilla than in the mandible. Deciduous dentition generally shows the following orders of eruption:

AB D C EA B D CE

• Central incisors• Lateral incisors• First molars• Canines• Second molars

By 3 years of age, the occlusion of deciduous dentition is completely established and dental arches remain relatively constant with no significant changes up to 6 years of age.

Mixed Dentition Stage (6–12 Years)Mixed dentition stage is a transition stage when primary teeth are exfoliated in a sequential manner, followed by the eruption of their permanent successors. This stage spans from 6 to 12 years of age, beginning with the eruption of the first permanent tooth, usually a mandibular central incisor or a first molar. It is completed at the time the last primary tooth is shed. Significant changes in occlusion are seen in mixed dentition period due to the loss of 20 primary teeth and eruption of their successor permanent teeth. Most malocclusions are developed at this stage.

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Permanent Dentition StagePermanent dentition stage is pretty well established by about 13 years of age, with the eruption of all permanent teeth except the 3rd molars. Permanent successors develop from lingual extension of the dental lamina (successional lamina) and the permanent molar develop from the posterior extension of the dental lamina. The permanent incisors develop lingual to the primary incisors and move labially as they erupt. The premolars develop below the divergent roots of the primary molars. Permanent dentition begins to form at birth, at which time, calcification of the 1st permanent molars becomes evident. Chronology of permanent dentition is depicted in Table 11.1. Sequence of eruption of permanent dentition is more variable than that of the primary dentition. In addition, there are significant differences in the eruption sequences between the maxillary and the mandibular arch.

Most Common Eruption Sequence in Maxilla6-1-2-4-3-5-7-8 or6-1-2-4-5-3-7-8

Most Common Eruption Sequence for Mandibular Arch

(6-1)-2-3-4-5-7-8 or(6-1)-2-4-3-5-7-8

These are also the most favorable sequences for the prevention of malocclusion. It must be noted that, there is a difference in eruption timing of the canines in the two arches. In the mandibular arch, the canine erupts before the premolars, whereas in the maxillary arch the canine generally erupts after the premolars. When second molars erupt before the premolars are fully erupted significant shortening of the arch perimeter occurs, increasing the likelihood of malocclusion.

Cephalometric Landmarks on DentitionCephalometric landmarks seen on the Dentition are of anatomic origin and are as follows (Table 11.1):

Incision Superius Incisalis

AbbreviationIsi–Incision Superius Incisalis is abbreviated using English alphabets and is expressed as Capital or upper case I followed by small letters or lower case s and i and is written continuously without any space between the alphabets.

is–Incision Superius is abbreviated using English alphabets and is expressed as small letters or lower case i and s and is written continuously without any space between the alphabets.

DefinitionIncision superius Incisalis (Figs 11.1A to D) is the incisal edge of the maxillary central incisor.

According to Arne BjorkIncision superius incisalis is the mid-point of the incisal edge of the most prominent upper central incisor.1

According to Robert E MoyersIncision superius incisalis is the incisal tip of the most anterior maxillary central incisor.2

TypeIncision superius incisalis is a unilateral, hard tissue cephalo-metric landmark.

OriginIncision superius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Table 11.1: Cephalometric landmarks related to dentition



Incision superius incisalis

Isi Unilateral anatomic

Incision superius apicalis

Isa Unilateral anatomic

Incision inferius incisalis

Iii Unilateral anatomic

Incision inferius apicalis

Iia Unilateral anatomic

anterior point of occlusion

apocc Unilateral anatomic

posterior point of occlusion

ppocc Unilateral anatomic

Maxillary central incisor

U1 Unilateral anatomic

Maxillary first molar U6 Bilateral anatomic

Mandibular central incisor

L1 Unilateral anatomic

Mandibular first molar

L6 Bilateral anatomic

mi mi Bilateral anatomic

ms ms Bilateral anatomic

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Tracing of Incision Superius Incisalis on Lateral CephalogramThe labial and lingual outline of the crown of the maxillary permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of Incision Superius Incisalis.

Significance (Ref to Chapter 20)Incision superius incisalis is used as one of the reference points in the construction of angles and planes for the assessment of following:

• Inclination of upper incisor is assessed using angle drawn between the long axis of upper incisor plane and the FH plane.

• In Arnett’s analysis, the upper incisor torque is assessed using the angle drawn between long axis of upper incisor and occlusal plane.

• Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisor.

• Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the NA plane.

• Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the A-Pog plane.

Figures 11.1A to D: (A) Incision superius incisalis on lateral cephalogram; (B) Magnified image showing incision superius Incisalis on the lateral cephalogram; (C) Incision superius incisalis on graphic illustration; (D) Magnified image of incision superius Incisalis on graphic illustration

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Incision Superius Apicalis

AbbreviationIsa–Incision Superius Apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case s and a and is written continuously without any space between the alphabets.UIA–Upper incisor apex is abbreviated using English alphabets and is expressed as capital or upper case U, I and A and is written continuously without any space between the alphabets.

DefinitionIncision superius apicalis (Figs 11.2A to D) is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

According to Michael L RioloThe upper incisor apex is the root tip of the maxillary central incisor. In cases where the root is not yet completed, the midpoint of the growing root tip is marked.3

According to SN Bhatia and BC Leighton

The upper incisor apex is the root apex of the most prominent upper incisor.4

Type

Incision superius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

OriginIncision superius apicalis is an anatomic hard tissue cephalo-metric landmark.

Figures 11.2A to D: Incision superius apicalis

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Tracing of Incision Superius Apicalis on Lateral CephalogramThe labial and lingual outline of the root of the maxillary permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent central incisor. The point of intersection of labial and lingual outlines of the root of maxillary permanent central incisor is the point of incision superius apicalis.

Significance (Ref to Chapter 20)Incision superius apicalis is used as one of the reference points in the construction of angles and planes for the assessment of following:• Inclination of upper incisor is assessed using angle drawn

between the long axis of upper incisor plane and the FH plane.


• Inter-incisal relationships of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisor.

Incision Inferius Incisalis

AbbreviationIii–Incision inferius incisalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case i and i and is written continuously without any space between the alphabets.

ii–Incision inferius is abbreviated using English alphabets and is expressed as small letters or lower case i and i and is written continuously without any space between the alphabets.

DefinitionIncision inferius incisalis (Figs 11.3A to D) is the incisal edge of the most prominent mandibular central incisor.

Figures 11.3A to D: Incision inferius incisalis (A and B) on lateral cephalogram, (C and D) on graphic illustration

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According to Arne BjorkThe incision inferius is the incisal point of the most prominent medial mandibular incisor.1

According to Robert E MoyersThe incision inferius is the incisal tip of the most labial mandi-bular central incisor.2

TypeIncision inferius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Inferius Incisalis on Lateral CephalogramThe labial and lingual outline of the crown of the mandibular permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of incision inferius incisalis.

Significance (Ref to Chapter 20)Incision inferius incisalis is used as one of the reference point in the construction of angles and planes for the assessment of following:• Inclination of lower incisor is assessed using angle drawn

between the long axis of lower incisor plane and the mandibular plane.

• In Arnett’s analysis, the lower incisor torque is assessed using the angle drawn between long axis of lower incisor and occlusal plane.


• Anteroposterior positioning of mandibular central incisor is assessed using the distance between the incision inferius incisalis and the NB plane.

• Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision inferius incisalis and the A-Pog plane.

Incision Inferius Apicalis

AbbreviationIia–Incision inferius apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed

by small letters or lower case i and a and is written continuously without any space between the alphabets.

LIA–Lower incisor apex is abbreviated using English alphabets and is expressed as capital or upper case L, I and A and is written continuously without any space between the alphabets.

DefinitionIncision inferius apicalis (Figs 11.4A to D) is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

According to SN Bhatia and BC LeightonThe lower incisor apex is the root apex of the most prominent lower incisor.4

TypeIncision inferius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Inferius Apicalis on Lateral CephalogramThe labial and lingual outline of the root of the mandibular permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent central incisor. The point of intersec-tion of labial and lingual outlines of the root of mandibular permanent central incisor is the point of incision inferius apicalis.

Significance (Ref to Chapter 20)Incision inferius apicalis is used as one of the reference points in the construction of angles and planes for the assessment of following:• Inclination of lower incisor is assessed using angle drawn

between the long axis of upper incisor plane and the mandibular plane.


• Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisors.

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Anterior Point of Occlusion

AbbreviationAPocc–Anterior point of occlusion is abbreviated using English alphabets and is expressed as capital or upper case A and P followed by small letters or lower case o, c and c and written continuously without any space between the alphabets.

DefinitionAnterior point of occlusion (Figs 11.5A to D) for the occlusal plane–A constructed point, the midpoint of the incisor overbite in occlusion.

TypeAnterior point of occlusion is a unilateral, constructed, hard tissue cephalometric landmark.

Tracing of Anterior Point of Occlusion on Lateral Cephalogram• The labial and lingual outline of the crown of the maxillary

permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor.

• The labial and lingual outline of the root of the maxillary permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent central incisor.

• The labial and lingual outline of the crown of the mandibular permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor.

• The labial and lingual outline of the root of the mandibular permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent central incisor.

Figures 11.4A to D: Incision inferius apicalis

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• Locate the point where there is maximum intercuspation of maxillary and mandibular permanent central incisors, which is the point of anterior point of occlusion.

Significance (Ref to Chapter 20)Anterior point of occlusion is used as one of the reference points in the construction of angles and planes for the assessment of the following:• Growth pattern is assessed using angle drawn between the

occlusal plane and mandibular plane.• Growth pattern is assessed using angle drawn between the

occlusal plane and FH plane.• In Arnett’s analysis, the upper incisor torque is assessed

using the angle drawn between long axis of upper incisor and occlusal plane.


Posterior Point of Occlusion

Abbreviation

PPocc–Anterior point of occlusion is abbreviated using English alphabets and is expressed as capital or upper case P and P followed by small letters or lower case o, c and c and are written continuously without any space between the alphabets.

DefinitionPosterior point of occlusion (Figs 11.6A to D) for the occlusal plane—the most distal point of contact between the most posterior molars in occlusion (Rakosi).

TypePosterior point of occlusion is a bilateral, anatomic hard tissue cephalometric landmark.

Figures 11.5A to D: Anterior point of occlusion

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Tracing of Posterior Point of Occlusion on Lateral Cephalogram• The labial and lingual outline of the crown of the maxillary

permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent first molar.

• The labial and lingual outline of the root of the maxillary permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent first molar.

• The labial and lingual outline of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent first molar.

• The labial and lingual outline of the root of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent first molar.

• Locate the point where there is maximum intercuspation of maxillary and mandibular permanent first molars, which is the point of anterior point of occlusion.


Posterior point of occlusion is used as one of the reference points in the construction of angles and planes for the assessment of following:• Growth pattern is assessed using angle drawn between the

occlusal plane and mandibular plane.• Growth pattern is assessed using angle drawn between the

occlusal plane and FH plane.• In Arnett’s analysis, the upper incisor torque is assessed

using the angle drawn between long axis of lower incisor and occlusal plane.


Figures 11.6A to D: Posterior point of occlusion

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Maxillary Central Incisor

AbbreviationU1–Maxillary central incisor is abbreviated using English alphabets and numeric and is expressed as Capital or upper case U followed by English numeric 1 and is written continuously without any space between them.

DefinitionMaxillary central incisor (Figs 11.7A to D) is the most labial point on the crown of the maxillary central incisor.

Type

Maxillary central incisor is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Maxillary Central Incisor on Lateral Cephalogram

The labial and lingual outline of the crown of the maxillary permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor. The most labial point on the crown of the maxillary central incisor is the point of maxillary central incisor.

Maxillary First Molar

AbbreviationU6–Maxillary first molar is abbreviated using English alphabets and numeric and is expressed as capital or upper case U followed by English numeric 6 and is written continuously without any space between the alphabets.

Figures 11.7A to D: Maxillary central incisor

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DefinitionMaxillary first molar (Figs 11.8A to D) is the tip of the mesiobuccal cusp of the maxillary first permanent molar.

TypeMaxillary first molar is a bilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Maxillary First Molar on Lateral CephalogramThe labial and lingual and cuspal outlines of the crown of the maxillary permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the max-illary permanent first molar, the tip of the mesiobuccal cusp of the maxillary permanent molar is the point of maxillary first molar.

Mandibular Central Incisor

AbbreviationL1–Mandibular central incisor is abbreviated using English alphabets and numeric and is expressed as capital or upper case L followed by English numeric 1 and is written continuously without any space between the alphabets.

DefinitionMandibular central incisor (Figs 11.9A to D) is the most labial point on the crown of the mandibular central incisor.

TypeMandibular central incisor is a unilateral, anatomic, hard tissue cephalometric landmark.

Figures 11.8A to D: Maxillary first molar

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Tracing of Mandibular Central Incisor on Lateral CephalogramThe labial and lingual outlines of the crown of the mandibular permanent central incisor appear as radio-opaque lines on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor. The most labial point on the crown of the mandibular central incisor is the point of mandibular central incisor.

Mandibular First Molar

AbbreviationL6–Mandibular first molar is abbreviated using English alphabets and numerical and is expressed as capital or upper case L followed by English numeric 6 and is written continuously without any space between the alphabets.

Definition

Mandibular first molar (Figs 11.10A to D) is the tip of the mesiobuccal cusp of the mandibular first permanent molar.

Type

Mandibular first molar is a bilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Mandibular First Molar on Lateral CephalogramThe labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar.

Figures 11.9A to D: Mandibular central incisor

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mi

Abbreviationmi–mi is abbreviated using English alphabets and is expressed as lower case m and i and written continuously without any space between the alphabets.

Definitionmi (Figs 11.11A to D) is the mesial contact of the lower molar projected normal to the plane of occlusion.

Typemi is a bilateral, hard tissue cephalometric landmark.

Tracing of mi on Lateral CephalogramThe labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar. mi is the mesial contact of the lower molar projected normal to the plane of occlusion.

Figures 11.10A to D: Mandibular first molar

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Significance (Ref to Chapter 20)mi is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.

ms

Abbreviationms–ms is abbreviated using English alphabets and is expressed as lower case m and s and written continuously without any space between the alphabets.

Definitionms (Figs 11.12A to D) is the mesial contact of the upper molar projected normal to the plane of occlusion.

Typems is a bilateral hard tissue cephalometric landmark.

Tracing of ms on Lateral CephalogramThe labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of

Figures 11.11A to D: mi

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crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar. ms is the mesial contact of the upper molar projected normal to the plane of occlusion.

Significance (Ref to Chapter 20)ms is used as one of the reference point in the construction of plane and angle in the Bjork cephalometric analysis.

Figures 11.12A to D: ms

References 1. Arne Bjork. The face in profiles-Sven. Tandlak Tidskr. 1947;40:32-3. 2. Robert M Moyers. Handbook of Orthodontics–Year Book Medical

Publishers, Inc. 1988;251-9. 3. Michael L Riolo. An atlas of craniofacial growth: Cephalometric

standards from the university school growth study, the University of Michigan. Center for human growth and development. The University of Michigan. 1974;12-21.

4. Bhatia SN, Leighton BC. A manual of facial growth. Oxford University Press. 1993;10-5.

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12 Cephalometric Landmarks Related to Mandible

The mandible (Fig. 12.1 ) (from Latin mandibula—jawbone) or inferior maxillary bone forms the lower jaw and holds the lower teeth in place.

Cephalometric landmarks (Points) on MandibleCephalometric landmarks on mandible are as follows (Table 12.1):

• Mandibular foramen, paired, in the inner (medial) aspect of the mandible, superior to the mandibular angle in the middle of the ramus.

• Mental foramen, paired, lateral to the mental protuberance on the body of mandible.

Nerve Supply to Mandible

Inferior alveolar nerve, branch of the mandibular division of trigeminal (V) nerve, enters the mandibular foramen and runs forward in the mandibular canal, supplying sensation to the teeth. At the mental foramen the nerve divides into two terminal branches: Incisive and mental nerves. The incisive nerve runs forward in the mandible and supplies the anterior teeth. The mental nerve exits in the mental foramen and supplies sensation to the lower lip.

Figure 12.1: Mandible

Table 12.1: Cephalometric landmarks related to mandible



Infradentale Id Unilateral anatomic

point B part B Unilateral anatomic

pogonion pog Unilateral anatomic

Gnathion Gn Unilateral anatomic

dd dd Unilateral anatomic

Menton Me Unilateral anatomic

Gonion Go Unilateral anatomic

Articulare ar Bilateral anatomic

kk kk Unilateral anatomic

Condylion Cd Bilateral anatomic

Parts of Mandible The mandible consists of:• A curved, horizontal portion, the body.• Two perpendicular portions, the rami, which unite with

the ends of the body nearly at right angles.• Alveolar process, the tooth bearing area of the mandible.• Condyle, superior (upper) and posterior projection from

the ramus, which makes the temporomandibular joint with the temporal bone.

• Coronoid process, superior and anterior.• Projection from the ramus. This provides attachment to

the temporalis muscle.

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Articulations

The mandible articulates with the two temporal bones at the temporomandibular joints.

Infradentale

AbbreviationId–Infradentale is abbreviated using English alphabets and is expressed as capital or upper case I followed by lower case or small letters d and written continuously without any space between the alphabets.

Definition

According to Arne BjorkThe infradentale (Figs 12.2A to D) is the point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection.

According to Robert M MoyersThe infradentale is the most anterior superior point on the mandibular alveolar process, usually found near cement-enamel junction of the mandibular incisors.

Figures 12.2A to D: Infradentale

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According to SN Bhatia and BC leightonThe infradentale is the most anterosuperior point on the labial crest of the mandibular alveolar process.

TypeInfradentale is a unilateral, anatomic hard tissue landmark.

Tracing of Infradentale on the lateral CephalogramThe alveolar crest between two mandibular permanent central incisors in the midline appears as radio-opaque lines on the lateral cephalogram. Trace these radio-opaque lines.The intersection of radio-opaque lines of interdental cortical plate in the alveolar crest region between two mandibular permanent central incisors, is the point of infradentale.

Significance (Ref to Chapter 20)Infradentale is used as one of the reference points in the construction of plane and angle for the assessment of mandibular prognathism in the anterior region using S-N-Id angle.

Point B

AbbreviationPoint B–Point B is abbreviated using English alphabets and is expressed as capital or upper case B.

According to William B DownsThe point B (Figs 12.3A to D) is the deepest midline point on the mandible between infradentale and pogonion.

Figures 12.3A to D: Point B

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According to TM GraberThepointBisanarbitrarymeasurepointontheanteriorprofilecurvature from the mandibular anthropometric landmark pogonion to the crest of the alveolar process. This most posterior point usually falls just anterior to the apices of the incisor teeth.

According to Alex Jacobson and W CaufieldPoint B is on a line perpendicular to FH, point B is the most posterior point in the concavity between the chin and mandibular alveolar process.

According to Robert E MoyersThe point B is the most posterior point of the bony curvature of the mandible below infradentale and above pogonion. B point usually is found near the apical third of the roots of the mandibular incisors and may be obscured during eruption oftheseteeth,whentheprofileofthechinisnotconcave,Bpoint cannot be determined.

Type

Point B is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Point B on the lateral Cephalogram

The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace this line from the infradentale to the point of pogonion.

It’s been tough task to establish the precise location of point B on the lateral cephalogram. To make it easy, try to locate infradentale and pogonion and then the mid deepest point is the point B.

SignificancePoint B is used as one of the reference points in the construction of plane and angle for the assessment of anteroposterior relationship of the mandible in relation to anterior cranial base using S-N-B angle.

Pogonion

AbbreviationPog–Pogonion is abbreviated using English alphabets and is expressed as capital or upper case P followed by lower case or small letters o and g and are written continuously without any space between the alphabets.

Definition

According to KKK lewMost anterior point of mandibular symphysis.

According to William B DownsPogonion (Figs 12.4A to D) is the most anterior point on the mandible in the midline.

According to TM GraberThe most anterior point on the symphysis of the mandible.

According to Robert M RickettsMost anterior point on the mental protuberance.

According to B Holly BroadbentMost anterior point on the symphysis of the mandible in the median plane when the head is viewed in Frankfort relation.

According to leslie G FarkasPogonion is the most anterior midpoint of the chin, located on the skin surface in front of the identical bony landmark of the mandible.

Robert E MoyersThe most anterior point on the contour of the chin, pogonion usually is located by drawing a tangent perpendicular to the mandibular plane or by a tangent dropped to the chin from nasion.

Alex Jacobson and W CaufieldMove the perpendicular line to FH forward then back to where itfirsttouchesthechin.Thisispogonion.

TypePogonion is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Pogonion on the lateral CephalogramThe labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible, the most prominent point is the point of pogonion.

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SignificancePogonion is used as one of the reference points in the con-struction of plane and angle for the assessment of anteroposte-rior relationship of the mandible in relation to anterior cranial base using S-N-Pog angle (Facial angle).

Gnathion

AbbreviationGn–Gnathion is abbreviated using English alphabets and is expressed as capital or upper case G followed by lower case or small letters n and is written continuously without any space between the alphabets.

DefinitionGnathion (Figs 12.5A to D) is a point on the chin determined by bisecting the angle formed by the facial and mandibular plane.

According to TM GraberGnathionisthemostoutwardandevertedpointontheprofilecurvature of the symphysis of the mandible.

According to Robert E MoyersThe most anterior inferior point in the lateral shadow of the chin. Ganthion usually is best determined by selecting the midpoint between pogonion and menton on the contour of the chin.

Figures 12.4A to D: Pogonion

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According to Viken SassouniMidpoint between pogonion and menton can be located at the intersection of the facial; line (Na-Pog) and the mandibular plane (lower border).

Alex Jacobson and W CaufieldA point located by taking the point between the anterior (Pogonion) and inferior (Menton) points of the bony chin.

Arne BjorkLowest point of the mandibular symphysis.

TypeGnathion is a unilateral, constructed or derived, hard tissue cephalometric landmark.

Tracing of Gnathion on the lateral Cephalogram

The labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two per-manent mandibular incisors in the midline to the point antero-inferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible, the most prominent point is the point of pogonion.The anteroinferior point of inferior border of the mandible in the midline is the point of menton. The ganthion is a constructed or derived hard tissue cephalometric point. Draw a line joining the point of pogonion to the menton, the midpoint of this line is the point of gnathion.

Figures 12.5A to D: Gnathion

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SignificanceGnathion is used as one of the reference points in the construction of plane and angle for the assessment of growth pattern using N-S-Gn angle.

In Rickett’s cephalometric analysis, the positioning of the chin is determined by the angle formed between the Ba-N plane and plane from foramen rotundum (PT) to Gn. The normal value of this angle is 90 degree. A larger angle suggests a protrusive or forward growing chin whereas a lesser angle suggests a retropositioning of the chin.

dd

Abbreviationdd–dd is abbreviated using English alphabets and is expressed as lower case or small letters d and d and written continuously without any space between the alphabets.

Definitiondd (Figs 12.6A to D) is the most prominent point of the chin in the direction of measurement.

Typedd is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of dd on the lateral CephalogramThe labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible, the most prominent point is the point of pogonion. The anteroinferior point of inferior border of the mandible in the

Figures 12.6A to D: dd

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midline is the point of menton. The gnathion is a constructed or derived hard tissue cephalometric point. Draw a line joining the point of pogonion to the menton,the midpoint of this line is the point of gnathion. dd is the most prominent point of the chin in the direction of measurement.

Significancedd is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.

Menton

AbbreviationMe–Menton is abbreviated using English alphabets and is expressed as capital or upper case M followed by lower case or small letter e and is written continuously without any space between the alphabets.

According to Viken SassouniLower most point of the contour of the chin.

According to Carl F GuginoMenton (Figs 12.7A to D) is the point of the inferior border of the symphysis directly inferior to mental protuberance and inferior to the center of trigoniun mentali.

Type

Menton (Figs 12.7A to D) is a unilateral, anatomic, hard tissue landmark.

Tracing of Menton on the lateral CephalogramThe labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the

Figures 12.7A to D: Menton

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labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B fol-lows the convex outline of labial cortical plate of mandible,the most prominent point is the point of pogonion.The anteroinfe-rior point of inferior border of the mandible in the midline is the point of menton.

SignificanceMenton is used as one of the reference points in the construction of plane and angle for the assessment of following:• Constructions of mandibular plane, i.e. the line joining the

point menton and gonion.• Growth pattern is assessed using S-N to mandibular plane

angle.• Growth pattern is assessed using FH to mandibular plane

angle.• Cant of occlusal plane is assessed using occlusal plane

(APocc-Ppocc) to mandibular plane (Me-Go) angle.• Growth pattern is assessed using Go1 and Go2 angles.

Gonion

AbbreviationGo–Gonion is abbreviated using English alphabets and is expressed as capital or upper case G followed by lower case or small letter o and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe midpoint mediolaterally on the posterior border of each gonial angle.

According to KKK lewThe midpoint mediolaterally on the posterior most border of each gonial angle. Gonion is a bilateral structure.

TypeGonion (Figs 12.8A to D) is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Menton on the lateral CephalogramThe inferior and posterior borders of the mandible appear as radio-opaque lines on the lateral cephalogram.Trace these two

radio-opaque lines and then draw a line tangent to inferior and posterior/ramus borders of the mandible; the point where these two intersects is the point of gonion.

Improper positioning of head during cephalometric radio-graphic projection procedure will result in superimposition of right and left mandibular inferior border. In such cases, there are two radio-opaque lines of right and left mandibular inferior borders. Then trace these two radio-opaque lines and draw an imaginary line exactly middistance between right and left inferior borders of the mandible. To establish the point Gonion tangent line is drawn from the imaginary line and posterior border/ramus border, the instersection of these two lines is the point of Gonion.

SignificanceGonion is used as one of the reference points in the construction of plane and angle for the assessment of following:• Constructions of mandibular plane, i.e. the line joining the




(APocc-Ppocc ) to mandibular plane (AvMe-Go) angle.• Growth pattern is assessed using Go1 and Go2 angles.• Rotation of the mandible is also assessed using the S-Ar-

Go angle.• The length of the mandible is measured from condylion

to gonion.

Articulare

AbbreviationAr–Articulare is abbreviated using English alphabets and is expressed as capital or upper case A followed by lower case or small letter r and is written continuously without any space between the alphabets.

DefinitionArticulare (Figs 12.9A to D) is the point of intersection the dorsal contours of the processus articularis mandibulare and os tempoarle. The midpoint, a is used where double projection gives rise to two points, a1 and a2.

TypeArticulare is a bilateral, anatomic, hard tissue landmark.

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Tracing of Articulare on the lateral CephalogramThe posterior or ramus border of the mandible appears as radio-opaque line on the lateral cephalogram. Trace ramus border of the mandible. The point on the ramus border of the mandible at the neck region.

SignificanceArticulare is used as one of the reference points in the construction of plane and angle for the assessment of the following:• Construction of posterior/ramus border of the mandible,

i.e. the line joining the point Articulare and Gonion.• Growth pattern is assessed using Go1 and Go2 angles.• Rotation of the mandible is also assessed using the S-Ar-

Go angle.

kk

Abbreviationkk–kk is abbreviated using English alphabets and is expressed as lower case or small letters k and k and written continuously without any space between the alphabets.

Definitionkk is the point of intersection between the base and ramus tangents to the mandible. The midpoint is used where double projections gives rise to two points.

Typekk (Figs 12.10A to D) is a bilateral hard tissue cephalometric landmark.

Figures 12.8A to D: Gonion

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Tracing of Menton on the lateral Cephalogram

The inferior and posterior borders of the mandible appear as radio-opaque lines on the lateral cephalogram. Trace these two radio-opaque lines and then draw a line tangent to inferior and posterior/ramus borders of the mandible; the point where these two intersect is the point of gonion. kk is the point of intersection between the base and ramus tangents to the mandible. The midpoint is used where double projections give rise to two points.

Significance

kk is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.

Condylion

AbbreviationCd–Articulare is abbreviated using English alphabets and is expressed as capital or upper case C followed by lower case or small letter d and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergCondylion medialis (Figs 12.11A to D)–The tangent point to each medial condylar border of a line drawn parallel to each mandibular body line.

Figures 12.9A to D: Articulare

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According to KKK lewCondylion medialis–Most medial aspect of condyle. Bilateral structure.

According to Clifton T ForsbergCondylion lateralis–The tangent point in each condylar border of a line drawn parallel to each mandibular body line.

According to KKK lewCondylion lateralis–Most lateral aspect of condyle. Bilateral structure.

According to Clifton T ForsbergCondylion anterioris–A point on the anterior of each condylar head which is chosen to represent the mandibular fossa of the temporal bone.

According to Clifton T ForsbergCondylion posterialis–The intersection of the mandibular body line with the posterior border of each condyle.

TypeCondylion is a bilateral, anatomic, hard tissue cephalometric landmark.

Figures 12.10A to D: kk

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Tracing of Condylion on the lateral CephalogramThe posterior or ramus border of the mandible appears as radio-opaque line on the lateral cephalogram. Condyle of the mandible appears as a circular radio-opaque line on the lateral cephalogram. The highest point of superior curvature of the condyle of the mandible is the point of condylion.

SignificanceCondylion is used as one of the reference points in the construc-tion of plane and angle for the assessment of the following:

Figures 12.11A to D: Condylion

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• Construction of posterior/ramus border of the mandible, i.e. the line joining the point Articulare and Gonion.

• Growth pattern is assessed using Go1 and Go2 angles.• Rotation of the mandible is also assessed using the S-Ar-

Go angle.• Midfacial length is measured from condylion to point A in

McNamara analysis.• The length of the mandible is measured from condylion

to gonion.

Section 5Cephalometric Landmarks Related to Cervical Bones

Cephalometric Landmarks Related to Hyoid Bone Cephalometric Landmarks Related to Vertebrae

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13 Cephalometric landmarks related to hyoid bone

Like the mandible, the hyoid bone (Figs 13.1A and B) is also a horse-shoe shaped bone suspended in the neck.

Parts of the Hyoid BoneHyoid bone consists of the following parts:• A body.• Lesser cornu/horn.• Greater cornu/horn. The lesser cornu fuses the body of the hyoid bone superiorly whereas the greater cornu fuses the body of hyoid bone inferiorly.

Radiographic Anatomy of Hyoid Bone• The hyoid bone is well appreciated on the lateral cephalogram.• On the lateral cephalogram, the hyoid bone appears

boomerang-shaped radio-opaque area below the inferior to the middle of the mandibular body.

• The greater and lesser cornu of the hyoid bone appear as radio-opaque on the lateral cephalogram.

• The body of the hyoid bone on the lateral cephalogram appears as radio-opaque.

• In children, greater cornu is seen separately as it is not fused to the body of hyoid but in adults both lesser and greater cornu are fused to the body of hyoid bone.

Cephalometric Landmarks (Points) on Hyoid BoneCephalometric landmarks seen on the hyoid bone are of anatomic origin and are as follows:

Table 13.1: Cephalometric landmark related to hyoid bone

Cephalometric landmark


Hyoid Hy or H Unilateral anatomic

Hyoid

AbbreviationHy–Hyoid is abbreviated using English alphabet and is expressed as capital or upper case H followed by lower case or small y, and both are written continuously without any space between the alphabets.

Figures 13.1A and B: hyoid bone

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H–Hyoid is abbreviated using English alphabet and is expressed as capital or upper case H.

Note: Most widely and commonly used abbreviation for hyoid is Hy.

Definition

Hyoid (Figs 13.2A to D) is the most superoanterior point on the body of the hyoid bone.

According to Robert M RickettsAccording to Robert M Ricketts, the hyoid is the point at the anterior-superior margin of the body of the hyoid.1

TypeHyoid is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Hyoid on the Lateral CephalogramThe body, lesser and greater cornu of the hyoid bone appears as boomerang shaped radio-opaque area. The superioanterior point on the body of the hyoid bone is the point of hyoid. It is a unilateral, anatomic hard tissue cephalometric landmark.

Reference 1. Ricketts RR. Provocations and perceptions in cranio-facial orthopedics–

dental science and facial art. Rocky Mountain Inc. 1989;797-803.

Figures 13.2A to D: hyoid

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14Radiographic anatomy of cervical vertebrae (fig. 14.1)Anteroinferior to the occipital condyle, which appears as a curved radio-opaque line, the anterior arch of the atlas can be identified as a small triangular radio-opaque area. The apex of the triangle faces the posterior border of the mandibular ramus, while its base faces the odontoid process of the axis. The central mass of the atlas, which appears as radio-opaque area superimposed on the radio-opaque shadow of the odontoid process. Posterosuperior to the inferior articular facet is the superior articular facet, which can be identified as radio-opaque area. Its superior border is concave and corresponds with the contour of the occipital condyle. Next to the superior articular facet is the posterior arch with the posterior tubercle. At the superior border of the posterior arch is a groove for the vertebral artery and the first cervical nerve. The odontoid process and the body of the axis appear as a triangular radio-opaque area. The odontoid process represents the apex of the triangular points toward the occipital condyle. The spinous process of the axis appears as a radio-opaque projection extending superiorly. The radiographic appearance of the third cervical vertebra (C3) to the seventh cervical vertebra (C7) is similar. The body of the each of these cervical vertebrae appears as wedge shaped radio-opaque area situated behind the pharyngeal space. Posterior to the body is the spinous process. The transverse processes, the superior articular process and the inferior articular process appear as radio-opaque area superimposed on the shadow of the body and the spinous process. The body of each cervical vertebra is separated from the adjacent ones by the intervertebral disc, which appears as radiolucent strip. At the midpoint between the third and fourth cervical vertebrae is the hyoid bone, which is separated anteriorly.

cephalometric Landmarks on cervical vertebraCephalometric landmarks seen on the cervical vertebra are of anatomic origin and are as follows (Table 14.1):

Table 14.1: Cephalometric landmarks related to cervical vertebra

Cephalometriclandmarks


cv2ap cv2ap Unilateral anatomic

cv2ip cv2ip Unilateral anatomic

cv2ia cv2ia Unilateral anatomic

cv3sp cv3sp Unilateral anatomic


cv3sa cv3sa Unilateral anatomic














cephalometric Landmarks (Points) Related to cervical vertebra• cv2ap–The apex of the odontoid process of the second

cervical vertebra.• cv2ip–The most inferoposterior point on the body of the

second cervical vertebra.• cv2ia–The most inferoanterior point on the body of the

second cervical vertebra.

Cephalometric landmarks related to Vertebrae

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• cv3sp–The most superoposterior point on the body of the third cervical vertebra.

• cv3ip–The most inferoposterior point on the body of the third cervical vertebra.

• cv3sa–The most superoanterior point on the body of the third cervical vertebra.

• cv3ia–The most inferoanterior point on the body of the third cervical vertebra.

• cv4sp–The most superoposterior point on the body of the fourth cervical vertebra.

• cv4ip–The most inferoposterior point on the body of the fourth cervical vertebra.

• cv4sa–The most superoanterior point on the body of the fourth cervical vertebra.

• cv4ia–The most inferoanterior point on the body of the fourth cervical vertebra.

• cv5sp–The most superoposterior point on the body of the fifth cervical vertebra.

• cv5ip–The most inferoposterior point on the body of the fifth cervical vertebra.

• cv5sa–The most superoanterior point on the body of the fifth cervical vertebra.

• cv5ia–The most inferoanterior point on the body of the fifth cervical vertebra.

• cv6sp–The most superoposterior point on the body of the sixth cervical vertebra.

• cv6ip–The most inferoposterior point on the body of the sixth cervical vertebra.

• cv6sa–The most superoanterior point on the body of the sixth cervical vertebra.

• cv6ia–The most inferoanterior point on the body of the sixth cervical vertebra.

cv2ip

abbreviationcv2ip–cv2ip is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 2 and then it is followed with English alphabets lower case i and p and all of them are written continuously without any space between the alphabets.

DefinitionThe most inferoposterior point on the body of the second cervical vertebra.

Typecv2ip (Figs 14.2A and B) is a unilateral, anatomic, hard tissue cephalo metric landmark.

SignificanceThis cephalometric landmark/point is used as a reference point in the cervical vertebrae maturity indicator (CMVI) method.

cv2ap

abbreviationcv2ap–cv2ap is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 2 and then it is followed with English alphabets lower case a and p and all of them are written continuously without any space between the alphabets.

DefinitionThe apex of the odontoid process of the second cervical vertebra.

Typecv2ap (Figs 14.3A and B) is a unilateral, anatomic, hard tissue cephalo metric landmark.


Figure 14.1: radiographic anatomy of cervical vertebra

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Figures 14.2A and B: cv2ip-The most inferoposterior point on the body of the second cervical vertebra

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Figures 14.3A and B: cv2ap-The apex of the odontoid process of the second cervical vertebra

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Figures 14.4A and B: cv2ia-The most inferioanterior point on the body of the second cervical vertebra

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cv2ia

abbreviationcv2ia–cv2ia is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 2 and then it is followed with English alphabets lower case i and a and all of them are written continuously without any space between the alphabets.

DefinitionThe most inferoanterior point on the body of the second cervical vertebra.

Typecv2ia (Figs 14.4A and B) is a unilateral, anatomic, hard tissue cephalo metric landmark.


cv3sp

abbreviationcv3sp–cv3sp is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 3 and then it is followed with English alphabets lower case s and p and all of them are written continuously without any space between the alphabets.

DefinitionThe most superoposterior point on the body of the third cervical vertebra.

Typecv3sp (Figs 14.5A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


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cv3ip


DefinitionThe most inferoposterior point on the body of the third cervical vertebra.



cv3sa

abbreviationcv3sa—cv3sa is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 3 and then it is followed with English alphabets lower case s and a and all of them are written continuously without any space between the alphabets.

DefinitionThe most superoanterior point on the body of the third cervical vertebra.

Typecv3sa (Figs 14.7A and B) is a unilateral, anatomic, hard tissue cephalo metric landmark.


Figures 14.5A and B: cv3sp-The most superoposterior point on the body of the third cervical vertebra

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Figures 14.6A and B: cv3ip-The most inferoposterior point on the body of the third cervical vertebra

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Figures 14.7A and B: cv3sa-The most superoanterior point on the body of the third cervical vertebra

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Figures 14.8A and B: cv3ia-The most inferioanterior point on the body of the third cervical vertebra

cv3ia


DefinitionThe most inferoanterior point on the body of the third cervical vertebra.

Typecv3ia (Figs 14.8A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


cv4sp


DefinitionThe most superoposterior point on the body of the fourth cervical vertebra.



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cv4ip


DefinitionThe most inferoposterior point on the body of the fourth cervical vertebra.



cv4sa

abbreviationcv4sa–cv4sa is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 4 and then it is followed with English alphabets lower case s and a and all of them are written continuously without any space between the alphabets.

DefinitionThe most superoanterior point on the body of the fourth cervical vertebra.

Typecv4sa (Figs 14.11A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


Figures 14.9A and B: cv4sp-The most superoposterior point on the body of the fourth cervical vertebra

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Figures 14.10A and B: cv4ip-The most inferoposterior point on the body of the fourth cervical vertebra

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Figures 14.11A and B: cv4sa-The most superoanterior point on the body of the fourth cervical vertebra

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cv4ia


DEfINITIONThe most inferoanterior point on the body of the fourth cervical vertebra.

Typecv4ia (Figs 14.12A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


cv5sp

abbreviationcv5sp–cv5sp is abbreviated using English alphabet and English numerical and is expressed as small letters or lower case c,v followed by English numeric 5 and then it is followed with English alphabets lower case i and a and all of them are written continuously without any space between the alphabets.

DefinitionThe most superoposterior point on the body of the fifth cervical vertebra.



Figures 14.12A and B: cv4ia-The most inferoanterior point on the body of the fourth cervical vertebra

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Figures 14.13A and B: cv5sp-The most superoposterior point on the body of the fifth cervical vertebra

cv5ip


DefinitionThe most inferoposterior point on the body of the fifth cervical vertebra.

Typecv5ip (Figs 14.14A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


cv5sa


DefinitionThe most superoanterior point on the body of the fifth cervical vertebra.



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Figures 14.15A and B: cv5sa-The most superoanterior point on the body of the fifth cervical vertebra

Figures 14.14A and B: cv5ip-The most inferoposterior point on the body of the fifth cervical vertebra

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Figures 14.16A and B: cv5ia-The most inferoanterior point on the body of the fifth cervical vertebra

cv5ia


DefinitionThe most inferoanterior point on the body of the fifth cervical vertebra.

TypeCv5ia (Figs 14.16A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


cv6sp


DefinitionThe most superoposterior point on the body of the sixth cervical vertebra.



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cv6ip


DefinitionThe most inferoposterior point on the body of the sixth cervical vertebra.

Typecv6ip (Figs 14.18A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.


cv6sa


DefinitionThe most superoanterior point on the body of the sixth cervical vertebra.



Figures 14.17A and B: cv6sp-The most superoposterior point on the body of the sixth cervical vertebra

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Figures 14.18A and B: cv6ip-The most inferoposterior point on the body of the sixth cervical vertebra

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Figures 14.19A and B: cv6sa-The most superoanterior point on the body of the sixth cervical vertebra

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cv6ia

abbreviation

cv6ia–cv6ia is abbreviated using English alphabet and English numeric and is expressed as small letters or lower case c,v followed by English numeric 6 and then it is followed with English alphabets lower case i and a and all of them are written continuously without any space between the alphabets.

Definition

The most inferoanterior point on the body of the sixth cervical vertebra.

Type

cv6ia (Figs 14.20A and B) is a unilateral, anatomic, hard tissue cephalometric landmark.

Significance

This cephalometric landmark/point is used as a reference point in the cervical vertebrae maturity indicator (CMVI) method.

Figures 14.20A and B: cv6ia-The most inferoanterior point on the body of the sixth cervical vertebra

A B

cervical vertebrae as Indicators of Skeletal MaturityHand-wrist radiographs have been used conventionally as the standard method of evaluating skeletal maturity. Although accurate, this method necessitates additional radiation exposure to patients. Furthermore, the hand-wrist site is far removed from the jaw which is the site of orthodontic correction. In recent years, evaluation of cervical vertebrae has been increasingly used to determine skeletal maturation. A new system of skeletal maturation assessment using the cervical vertebrae was first developed by Hassel and Farman. A number of subsequent stu dies have shown significant correlation between developmental or maturational changes occurring in the cervical vertebrae than that of the hand-wrist region. Cervical vertebrae maturity indicator (CMVI) method is increasingly being used in the recent years instead of the conventional hand-wrist radiograph method. One of the main reasons for the rising popularity of the method is that cervical vertebral maturation can be assessed on lateral cephalograms (Fig. 14.21), which is used regularly in orthodontic diagnosis, thus precluding the need for an additional radiograph.

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Figure 14.21: Cervical vertebral maturation can be assessed on lateral cephalograms Figure 14.22: Hassel and Farman developed a method of skeletal

maturation assessment using cervical vertebrae in which there are 6 stages of development

In 1972, Lamparki stated that the cervical vertebrae were as statistically and clinically reliable in assessing skeletal age as the hand-wrist technique. Several authors (San-Roman et al 2002) have reported a high correlation between cervical vertebrae maturation and skeletal maturation of the hand-wrist. It has been found that cervical vertebrae could offer an alternative method for assessing maturity without the need of hand-wrist radiographs and thus decreasing patient’s radiation exposure. Most methods of cervical vertebral maturation are based on morphologic changes that occur in cervical vertebral bodies as growth progresses. Hassel and Farman developed a method of skeletal maturation assessment using cervical vertebrae in which there are 6 stages of development (Fig. 14.22). They take into account the morphologic characteristics of the cervical (C2, C3 and C4) vertebrae such as:• Shape of the vertebral bodies• Height of the vertebral bodies• Concavity of the lower border of the cervical bodies. The shapes of the cervical vertebral bodies of C3 and C4 change at each level of skeletal development are assessed (Fig. 14.23).• At first they are wedge-shaped, then changed to rectangular,

next to square-shaped.• The vertical dimensions of the cervical vertebral bodies

increase with increased skeletal maturity.• It is also observed that the inferior borders of the cervical

vertebral bodies which are flat at the beginning become concave as they mature.

• The concavity of the inferior vertebral borders is seen to appear sequentially from C2 to C3 and then to C4 as the skeleton matures.

Figure 14.23: The shapes of the cervical vertebral bodies of C3 and C4 change at each level of skeletal development are assessed

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Stage Name Changes in vertebrae

Stage 5 Maturation • Cervical vertebrae attain maturity• Concavities at lower borders of C2, C3 and

C4 become more accentuated• C3 and C4 are more square in shape• 5–10% pubertal growth remaining

Stage 6 Completion • Adolescent growth is nearly complete• More accentuated concavities are seen at

lower borders of C2, C3 and C4.• Shape of C3 and C4 is square with greater

vertical dimension than width• Pubertal growth is complete with no more

growth potential remaining.

Bibliography 1. Anderson Dl, Thompson GW, Popovich F. Interrelationship of dental

maturity, skeletal maturity, height and weight from age 4 to 14 years, Growth. 1975;39:453-62.

2. Bowden BD. Epiphyseal changes in the hand/wrist area as an indicator of adolescent. Aust Orthod J. 1976;4:87-104.

3. Fishman LS. Radiographic evaluation of skeletal maturity. Angle Orthodont. 1982;88-112.

4. Grave, Brown. Skeletal ossification and adolescent growth spurt. Am J Orthod. 1976;69-80.

5. Houston WJB, Miller JC, Tanner JM. pRediction of the timing of the adolescent growth spurt from ossification events in hand/wrist films, Brit J Ortho. 1979;6:145-52.

6. Moore, Moyer, Dubois. Skeletal maturation and craniofacial growth. Am J Orthod. 1990;33-40.

7. Revelo, Fishman. Evaluation of ossification of midpalatal suture. Am J Orthod. 1994;288-92.Contd...

Contd... Depending on these changes observed in C2, C3 and C4 cervical vertebrae, Hassel and Farman gave 6 stages of development depicted in Table 14.2.

Table 14.2: Assessment of skeletal maturity using cervical vertebrae

Stage Name Changes in vertebrae

Stage 1 Initiation • Marks the beginning of adolescent growth.• The cervical vertebral bodies and C2, C3 and

C4 are wedge-shaped with their superior borders tapering postero anteriorly.

• Their inferior borders are flat.• 80–95% of growth in remaining pubertal.

Stage 2 Acceleration • Acceleration of growth occurs.• Concavities are developing on the lower

borders of C2 and C3• Lower border of C4 vertebral body is flat• C3 and C4 assume rectangular shape• 65–85% of pubertal growth remains

Stage 3 Transition • Growth is accelerated to reach peak height velocity

• Distinct concavity seen in lower borders of C2 and C3.

• Concavity is developing in the lower borders of C4.

• C3 and C4 are more rectangular in shape.• 25–65% pubertal growth is remaining

Stage 4 Deceleration • Deceleration of adolescent growth spurt begins

• Distinct concavities seen at the lower borders of all three vertebrae, that is, C2, C3 and C4

• C3 and C4 are nearly square in shape• 10–25% of pubertal growth is remain ing

Section6Cephalometric landmarks

related to Pharynx

Cephalometric landmarks related to Pharynx

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15 Cephalometric landmarks related to Pharynx

The pharynx is a median fibromuscular tube that extends from the base of the skull. Pharynx opens into nasal cavity, the oral cavity, and the larynx. Pharynx opens into the nasal cavity, the oral cavity and the larynx are termed as nasopharynx, oropharynx and laryngopharynx respectively.

NasopharynxThe Nasopharynx is the upper part of the pharynx. It is situated behind the oral cavity above the soft palate. Its superior border is the base of the skull. In the posterior part of the roof and the upper part of the posterior wall, there is an accumulation of lymphoid tissue—the adenoid or pharyngeal tonsil—which may be prominent in children but which becomes indistinct in adulthood. In the lateral wall, 1.5 cm posterior to the inferior nasal concha, is the opening of the auditory tube.The nasopharynx extends downwards and is continuous with the oropharynx at the level below the soft palate.

OropharynxThe oropharynx is the middle part of the pharynx situated between the soft palate and the superior border of the epiglottis. Anteriorly, it opens to the oral cavity and is bordered by the posterior one-third of the tongue. At the lateral boundaries of the opening of the oral cavity into the oropharynx, the palatine tonsils are lodged in the tonsilar fossae.

LaryngopharynxThe laryngopharynx is the lower part of the pharynx. It extends from the superior border of the epiglottis to the inferior border of the sixth cervical vertebrae, where it becomes continuous with the esophagus. The upper part of the laryngopharynx is open anteriorly to the larynx via the patent inlet.

Cephalometric Landmarks (Points) on PharynxCephalometric landmarks seen on the pharynx are of anatomic origin and are as follows (Table 15.1):

Table 15.1: Cephalometric landmarks related to pharynx



anterior nasal spine aNS or ans Unilateral anatomic

Posterior nasal spine PNS or pns Unilateral anatomic

anterior pharyngeal wall

apw Unilateral anatomic

Posterior pharyngeal wall

ppw Unilateral anatomic

Pterygomaxillaryfissure

Ptm Unilateral anatomic

Superior pharyngeal wall

spw Unilateral anatomic

Tip of uvula U Unilateral anatomic

Point on the oral side of the soft palate

Uo Unilateral anatomic

Point on thepharyngeal side ofthe soft palate

Up Unilateral anatomic

Upper point oftongue

ut Unilateral anatomic

Anterior Nasal Spine, Posterior Nasal Spine

and Pterygomaxillary FissureAnterior nasal spine, posterior nasal spine and pterygo-maxillary fissure are explained in detail in Chapter 10 [Cephalometric Landmarks (Points) Related to Maxilla].

Anterior Pharyngeal Wall

Abbreviation apw–Anterior pharyngeal wall is abbreviated using English alphabet and is expressed as small letters or lower case, a, p and w and written continuously without any space between the alphabets.

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Posterior Pharyngeal Wall

Abbreviationppw–Posterior pharyngeal wall is abbreviated using English alpha-bet and is expressed as small letters or lower case, p, p and w and written continuously without any space between the alphabets.

Superior Pharyngeal Wall

Abbreviationspw–Superior pharyngeal wall is abbreviated using English alpha-bet and is expressed as small letters or lower case, s, p and w and written continuously without any space between the alphabets.

Tip of the Uvula

Abbreviation U–Tip of the uvula is abbreviated using English alphabet and is expressed as capital or upper case U.

Point on the Oral Side of the Soft Palate

AbbreviationUo–Point on the oral side of the soft palate is abbreviated using English alphabet and is expressed as capital or upper case U followed by small letter or lower case o and is written continuously without any space between the alphabets.

Point on the Pharyngeal Side of the Soft Palate

AbbreviationUp–Point on the oral side of the soft palate is abbreviated using English alphabet and is expressed as capital or upper

case U followed by small letter or lower case p and is written continuously without any space between the alphabets.

Upper Point of Tongue

Abbreviation ut—Upper point of tongue is abbreviated using English alphabet and is expressed as small letters or lower case u and t and is written continuously without any space between the alphabets.

Significance

In Mc Namara Analysis

Upper pharynx

Upper pharyngeal width is measured from a point on the posterior outline of the soft palate to the closet point on the pharyngeal wall. This measurement is taken on the anterior half of the soft palate outline. The average nasopharnyx is approximately 15–20 mm in width. A width of 2 mm or less in this region indicates airway impairment.

Lower pharynx

Lower pharyngeal width is measured from the point of intersection of the posterior border of the tongue and the inferior border of the mandible to the closet point on the posterior pharyngeal wall. The average measurement is 11 to 14 mm independent of age. Greater than average lower pharyngeal walls is of possible anterior positioning of the tongue, either as a result of habitual posture or due to tonsillar enlargements A lower than average lower pharyngeal wall indicates the posterior positioning of the tongue.

Section7Soft Tissue Cephalometric

Landmarks

SoftTissueCephalometricLandmarks

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16 Soft Tissue Cephalometric Landmarks

Soft Tissue Cephalometric Landmarks (Points) Related to ForeheadSoft tissue cephalometric landmarks related to forehead are listed below and are explained in detail in this chapter.• Trichion• Soft tissue glabella.

Soft Tissue Glabella

Abbreviation• G–Soft tissue glabella is abbreviated using English

alphabet and is expressed as upper case G.

• Gs–Some authors abbreviate soft tissue glabella as English alphabet upper case G followed by lower cases.

• SGLB–Some authors even abbreviate soft tissue glabella as English alphabets upper case S, G L and B written continuously without any space between each alphabet.

• Note–Soft tissue glabella can be abbreviated as upper case G or Gs or SGLB, However, G is the most widely used abbreviation.

Definition• Soft tissue glabella (Figs 16.1A to D) is the most prominent

or anterior point in the midsagittal plane of the forehead at the level of the superior orbital ridges.

Figures 16.1A to D: (A) Soft tissue glabella on lateral cephalogram; (B) Magnified image showing soft tissue glabella on the lateral cephalogram; (C) Soft tissue glabella on graphic illustration; (D) Magnified image of soft tissue glabella on graphic illustration

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• The most prominent or anterior point in mid-sagittal plane of the forehead at the level of the superior orbital ridges (SN Bhatia, BC Leighton, 1993).

TypeGlabella is a unilateral soft tissue cephalometric landmark.

SignificanceGlabella is used as one of the reference points in the construc-tion of facial angles.

Soft Tissue Cephalometric Landmarks Related to NoseSoft tissue cephalometric landmarks (points) related to nose are listed below:• Soft tissue nasion• Nasal crown• Pronasale• Point “T”• Alar crease junction.

All above mentioned soft tissue cephalometric landmarks/points related to nose are explained below:

Soft Tissue Nasion

Abbreviationn–Soft tissue nasion is abbreviated using English alphabet and is expressed as lower case n.

N–Soft tissue nasion can also be abbreviated using English alphabet and is expressed as upper case N.

DefinitionSoft tissue nasion (Figs 16.2A to D) is the concave or retruded point in the tissue overlying the area of the frontonasal suture.

According to Spiro J Chaconas in 1993Thepointofintersectionofthesofttissueprofilewithalinedrawn from the center of sella turcica through nasion.

Figures 16.2A to D: (A) soft tissue nasion on lateral cephalogram; (B) Magnified image showing soft tissue nasion on the lateral cephalogram; (C) Soft tissue nasion on graphic illustration; (D) Magnified image of soft tissue nasion on graphic illustration

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TypeSoft tissue nasion is a unilateral soft tissue cephalometric landmark.

SignificanceSoft tissue nasion is used as one of the reference points on the construction of nasion and soft tissue pogonion plane which is used along with the dorsum surface of nose to determine the nasal prominence and subsequently helps in evaluation of malocclusion pattern.

Nasal Crown

AbbreviationNC–Nasal crown is abbreviated using English alphabet and is expressed as capital (upper case) NC and written continuously without any space between alphabets.

DefinitionNasal crown (Figs 16.3A to D) is a point along the bridge of the nose halfway between soft tissue nasion (n) and pronasale (Pn).

TypeNasal crown is a unilateral soft tissue cephalometric landmark.

SignificanceNasal crown is used for the assessment of nasal contour.

Pronasale

AbbreviationPn–Pronasale is abbreviated using English alphabet and is expressed as capital (upper case) P followed by lower case n written continuously without any space between alphabets.

Prn–Pronasale is also abbreviated using English alphabet and is expressed as capital (upper case) P followed by lower case r and n and written continuously without any space between alphabets.

PRN–Pronasale can also be abbreviated using English alphabet and is expressed as capital (upper case) P, R and N and written continuously without any space between alphabets.

prn–Pronasale can also be abbreviated using English alphabet and is expressed as small (lower case) p, r and n and written continuously without any space between alphabets.

Figures 16.3A to D: (A) Nasal crown on lateral cephalogram; (B) Magnified image showing nasal crown on the lateral cephalogram; (C) Soft tissue nasal crown on graphic illustration; (D) Magnified image of nasal crown on graphic illustration

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DefinitionPronasale (Figs 16.4A to D) is the most prominent or anterior point of the nose.

According to SN Bhatia and BC Leighton in 1993The most prominent or anterior point of the nose tip.

According to Spiro J Chaconas in 1969Themostanteriorpointonthemidsagittalprofileofthenose.Incaseswhere the tipof thenosewasmore thanadefinitepoint, pronasale was determined by drawing a line parallel to the line nasion to pogonion tangent to the most anterior point onthemidsagittalprofileofthenose.

According to Leslie G Farkas in 1981Pronasale is the most protruded point of the apex nasi.This pointisdifficulttodetermineifthenasaltipisflat.

TypePronasale is a unilateral soft tissue cephalometric landmark.

Significance• Pronasale helps in the assessment of nasal tip projection.

• Pronasale is also used as one of the reference points in the construction of following planes for the assessment offollowing:

– Ricketts’ E-line used to assess the relationship of upper and lower teeth to the upper and lower lip.

Point “T”

AbbreviationPoint T is abbreviated using English alphabet and is expressed as capital T.

DefinitionThe point “T” is the midline point on the nasal tip taken at the level of the dome projecting points of the lower lateral cartilage.

TypePoint “T” (Figs 16.5A to D) is a unilateral constructed point soft tissue cephalometric landmark.

SignificancePoint “T” is used in the assessment of nasal tip projection.

Figures 16.4A to D: (A) Pronasale on lateral cephalogram; (B) Magnified image showing pronasale on the lateral cephalogram; (C) Pronasale on graphic illustration; (D) Magnified image of pronasale on graphic illustration

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Alar Crease Junction

AbbreviationACJ–Alar crease junction is abbreviated using English alphabet and is expressed as capital A,C and J.

DefinitionAlar crease junction is the most posterior point of the curved line formed by the alar crease.

TypeAlar crease junction (Figs 16.6A to D) is a bilateral constructed point soft tissue cephalometric landmark.

SignificanceAlar crease junction is used as a landmark for measuring nasal tip projection.

Subnasale

AbbreviationSn–Subnasale is abbreviated using English alphabet and is expressed as capital (upper case) S followed by small (lower

case) n written continuously without any space between them.

SN–Subnasale is abbreviated using English alphabet and is expressed as capital (upper case) S and N written continuously without any space between them.

sn–Subnasale is abbreviated using English alphabet and is expressed as lower case (Small alphabets) s and n written continuously without any space between them.

DefinitionSubnasale (Figs 16.7A to D) is the point at which the nasal septum between the nostrils merges with the upper cutaneous tip in the midsagittal plane.

According to TM Graber (1975)According to TM Graber, subnasale is the point where the lowermargin of the nasal septum is confluentwith theintegumental upper lip.

According to Spiro J Chaconas and SN BhatiaSubnasale is the point at which the nasal septum between the nostrils merges with the upper cutaneous lip in the midsagittal plane.

Figures 16.5A to D: (A) Point ‘T’ on lateral cephalogram; (B) Magnified image showing point ‘T’ on the lateral cephalogram; (C) Point ‘T’ on graphic illustration; (D) Magnified image of point ‘T’ on graphic illustration

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Figures 16.6A to D: (A) Alar crease junction on lateral cephalogram; (B) Magnified image showing Alar crease junction on the lateral cephalogram; (C) Alar crease junction on graphic illustration; (D) Magnified image of Alar crease junction on graphic illustration

Figures 16.7A to D: (A) Subnasale on lateral cephalogram; (B) Magnified image showing subnasale on the lateral cephalogram; (C) Subnasale on graphic illustration; (D) Magnified image of subnasale on graphic illustration

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TypeSubnasale is a unilateral soft tissue cephalometric landmark.

Significance• Subnasale helps in the assessment of nasal tip projection

and nasal height.• Subnasale is also used as one of the reference points in

the construction of following planes for the assessment of following:

– Burstone’s B line used to assess the relationship of upper and lower teeth to the upper and lower lip.

– Height of upper lip (Sn–Ls) can be assessed.

Soft Tissue Cephalometric Landmarks (Points) Related to LipsSoft tissue cephalometric landmarks (points) related to lips are listed below:

Related to Upper Lip• Softtissuesubspinale • Labralesuperius• Philtrum • Cuspidbow• Vermillionborderofupperlip

Related to Upper and Lower Lip Together• Stomion• Stomionsuperius• Stomioninferius

Related to Lower Lip• Labraleinferius• SofttissuepointB

All above mentioned soft tissue cephalometric landmarks (points) related to lips are explained below.

Soft Tissue Subspinale

AbbreviationSs–Soft tissue subspinale is abbreviated using English alphabet and is expressed as capital S followed by small s.

DefinitionSoft tissue subspinale (Figs 16.8A to D) is the point of greatest concavity in the midline of the upper lip between subnasale (Sn) and labrale superius (Ls).

Figures 16.8A to D: (A) Subspinale on lateral cephalogram; (B) Magnified image showing subspinale on the lateral cephalogram; (C) Subspinale on graphic illustration; (D) Magnified image of subspinale on graphic illustration

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TypeSoft tissue subspinale is a unilateral soft tissue cephalometric landmark.

SignificanceSoft tissue subspinale is also used as one of the reference points in the construction of following planes for the assessment of following:• Steiner’s S line used to assess the relationship of upper

and lower teeth to the upper and lower lip.

Labrale Superius

AbbreviationLs–Labrale superius is abbreviated using English alphabet and is expressed as capital L followed by small s.

DefinitionLabrale superius (Figs 16.9A to D) is the most anterior point on the margin of the upper membranous lip.

TypeLabrale superius is a unilateral soft tissue cephalometric landmark.

SignificanceLabrale superius is also used as one of the reference points in the construction of following planes for the assessment of the following:• Holdaway “H” line used to assess the relationship of upper

and lower teeth to the upper and lower lip.• Merfield’s “Z” angle used to assess the relationship of

upper and lower teeth to the upper and lower lip.• It is even used to measure the length of upper lip (Ls-Sn).• It can also be used to assess the planed incisor position

(PIP).

PhiltrumPhiltrum (Fig. 16.10) is the central and vertically oriented position of the upper lip situated between the two skin reliefs of the philtrum columns. There is gentle concavity on its lower portion, the philtrum dimple.

Figures 16.9A to D: (A) Labrale superius on lateral cephalogram; (B) Magnified image showing labrale superius on the lateral cephalogram; (C) Labrale superius on graphic illustration; (D) Magnified image of labrale superius on graphic illustration

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Figure 16.10: Philtrum Figure 16.11: Cuspid bow

Cuspid Bow (Fig. 16.11)The central linear portion of the upper lip while roll skin relief of the upper lip between the philtrum and the vermilion. It connects the inferior ends of the philtrum columns.

Vermilion (Fig. 16.12)The most anterior point on the vermilion of the upper lip showing in Figure 16.12.

Stomion

AbbreviationSto–Stomion is abbreviated using English alphabet and is expressed as capital S followed by small t and o.

DefinitionStomion (Figs 16.13A to D) is the median point of the oral embrassure when the lips are closed.

TypeStomion is a unilateral soft tissue cephalometric landmark. Figures 16.12: Vermillion

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Figures 16.13A to D: (A) Stomion on lateral cephalogram; (B) Magnified image showing stomion on the lateral cephalogram; (C) Stomion on graphic illustration; (D) Magnified image of stomion on graphic illustration

SignificanceStomion is established only at rest when teeth are in centric occlusion and centric relation. Presence of stomion indicates averagely positioned upper and lower teeth.

Labrale Inferius

AbbreviationLi–Labrale inferius is abbreviated using English alphabet and is expressed as capital L followed by small i.

DefinitionLabrale inferius (Figs 16.14A to D) is the most anterior point on the lower margin of the lower membrane lip.

TypeLabrale inferius is a unilateral soft tissue cephalometric landmark.

SignificanceLabrale inferius is also used as one of the reference points in the construction of following planes for the assessment of following:

• It is even used to measure the length of lower lip (Li-Me).• It can also be used to assess the planed incisor position

(PIP).

Soft Tissue Submentale (Soft Tissue Point B)

AbbreviationB–Soft tissue point B is abbreviated using English alphabet and is expressed as capital “B”.

DefinitionSoft tissue point B or Soft tissue submentale (Figs 16.15A to D)is the point of greatest concavity in the midline of the lip between labrale inferius (Li) and soft tissue pogonion (Pog’ or Pogs).

TypeSoft tissue point B or soft tissue submentale is a unilateral soft tissue cephalometric landmark.

Significance• Soft tissue point B or soft tissue submentale is used in the

assessment of deepness of submental.

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Figures 16.14A to D: (A) Labrale inferius on lateral cephalogram; (B) Magnified image showing labrale inferius on the lateral cephalogram; (C) Labrale inferius on graphic illustration; (D) Magnified image of labrale inferius on graphic illustration

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Figures 16.15A to D: (A) Soft tissue point B on lateral cephalogram; (B) Magnified image showing soft tissue point B on the lateral cephalogram; (C) Soft tissue point B on graphic illustration; (D) Magnified image of soft tissue point B on graphic illustration

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• Soft tissue pogonion is also used as one of the reference points in the construction of following planes for the assessment of following:

– It is even used to measure the length of lower lip (Li-Me).

– It can also be used to assess the planed incisor position (PIP).

Soft Tissue Cephalometric Landmarks Related to ChinSoft tissue cephalometric landmarks/points related to chin are listed below:• Soft tissue pogonion• Soft tissue gnathion

All above mentioned soft tissue cephalometric landmarks/points related to chin are explained below:

Soft Tissue Pogonion

AbbreviationPogs or Pog’–Soft tissue pogonion is abbreviated using English alphabet and is expressed as capital P followed by small o and g with s in subscript position. It can also be

denoted as capital P followed by small o and g’ ending with ’ as a superscript.

DefinitionSoft tissue pogonion (Figs 16.16A to D) is the most prominent or anterior point on the soft tissue chin in the midsagittal plane.

TypeSoft tissue pogonion is a unilateral soft tissue cephalometric landmark.

Significance• Soft tissue pogonion is used to the prominence of the chin.• Soft tissue pogonion is also used as one of the reference

points in the construction of following planes for the assessment of following:

– Steiner’s “S” line used to assess the relationship of upper and lower teeth to the upper and lower lip.

– Rickett’s E-line used to assess the relationship of upper and lower teeth to the upper and lower lip.

– Burstone’s B line used to assess the relationship of upper and lower teeth to the upper and lower lip.

– Holdaway “H” line used to assess the relationship of upper and lower teeth to the upper and lower lip.

Figures 16.16A to D: (A) Soft tissue pogonion on lateral cephalogram; (B) Magnified image showing soft tissue pogonion on the lateral cephalogram; (C) Soft tissue pogonion on graphic illustration; (D) Magnified image of soft tissue pogonion on graphic illustration

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Figures 16.17A to D: (A) Soft tissue gnathion on lateral cephalogram; (B) Magnified image showing soft tissue gnathion on the lateral cephalogram; (C) Soft tissue gnathion on graphic illustration; (D) Magnified image of soft tissue gnathion on graphic illustration

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Soft Tissue Gnathion

AbbreviationGns–Soft tissue gnathion is abbreviated using English alphabet and is expressed as capital G followed by small n with s in subscript position.

DefinitionSoft tissue gnathion (Figs 16.17A to D) is the midpoint between the most anterior and inferior points of the soft tissue chin in the midsagittal plane.

TypeSoft tissue gnathion is a unilateral constructed point soft tissue cephalometric landmark.

SECTION83D Cephalometric

Landmarks

3D Cephalometric Landmarks

CH

AP

TE

R

17 3D Cephalometric Landmarks

Vertex

AbbreviationV–Vertex is abbreviated using English alphabet and is expressed as capital or upper case V.

DefinitionVertex (Fig. 17.1) is the most superior point of calvarium in center line.

TypeVertex is an anatomic, unilateral, soft tissue cephalometric landmark.

SignificanceVertex is used as one of the reference points in the construction of angles and planes in 3D cephalometric analysis.

Soft Tissue Nasion

Abbreviationn–Soft tissue nasion is abbreviated using English alphabet and is expressed as small letter or lower case n.

N’–Soft tissue nasion can also be abbreviated using English alphabet and is expressed as upper case or capital letter N and ending with ’ in superscript position.

DefinitionSoft tissue nasion (Fig. 17.2) is the concave or retruded point in the tissue overlying the area of the frontonasal suture.

According to Spiro J ChaconasThe point of intersection of the soft tissue profile with a line drawn from the center of sella turcica through nasion.

Figure 17.1: Vertex (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.2: Soft tissue nasion (Image created with the Invivo5 software by Anatomage Inc.)

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TypeSoft tissue nasion is a unilateral, soft tissue cephalometric landmark.

SignificanceSoft tissue nasion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Pronasale

AbbreviationPn–Pronasale is abbreviated using English alphabets and is expressed as capital (upper case) P followed by lower case n written continuously without any space between alphabets.

Prn–Pronasale is also abbreviated using English alphabet and is expressed as capital (upper case) P followed by lower case r and n written continuously without any space between alphabets.

PRN–Pronasale can also be abbreviated using English alphabet and is expressed as capital (upper case) P, R and N written continuously without any space between alphabets.

prn–Pronasale can also be abbreviated using English alphabet and is expressed as small (lower case) p, r and n written cont-inuously without any space between alphabets.

DefinitionPronasale (Figs 17.3A and B) is the most prominent or anterior point of the nose.

According to SN Bhatia and BC Leighton in 1993The most prominent or anterior point of the nose tip..

According to Spiro J ChaconasThe most anterior point on the midsagittal profile of the nose. In cases where the tip of the nose was more than a definite point, pronasale was determined by drawing a line parallel to the line nasion to pogonion tangent to the most anterior point on the midsagittal profile of the nose.

According to Leslie G Farkas in 1981Pronasale is the most protruded point of the apex nasi. This point is difficult to determine if the nasal tip is flat.

TypePronasale is a unilateral, soft tissue cephalometric landmark.

SignificancePronasale is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Subnasale

AbbreviationSn–Subnasale is abbreviated using English alphabets and is expressed as capital (upper case) S followed by small (lower case) n written continuously without any space between them.

Figures 17.3A and B: Pronasale (Image created with the Invivo5 software by Anatomage Inc.)

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SN–Subnasale is abbreviated using English alphabet and is expressed as capital (upper case) S and N written continuously without any space between them.

sn–Subnasale is abbreviated using English alphabet and is expressed as lower case (small alphabets) s and n written continuously without any space between them.

DefinitionSubnasale (Fig. 17.4) is the point at which the nasal septum between the nostrils merges with the upper cutaneous tip in the midsagittal plane.

According to TM Graber (1975)According to TM Graber, subnasale is the point where the lower margin of the nasal septum is confluent with the integumental upper lip.

According to Spiro J Chaconas (1980) and SN Bhatia

According to Spiro J Chaconas (1980) subnasale is the point at which the nasal septum between the nostrils merges with the upper cutaneous lip in the midsagittal plane.

Type

Subnasale is a unilateral, soft tissue cephalometric landmark.

SignificanceSubnasale is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Soft Tissue Subspinale

AbbreviationSs–Soft tissue subspinale is abbreviated using English alphabets and is expressed as capital S followed by small letter or lower case s and is written continuously without any space between the alphabets.

DefinitionSoft tissue subspinale (Fig. 17.5) is the point of greatest concavity in the midline of the upper lip between subnasale (Sn) and labrale superius (Ls).

TypeSoft tissue subspinale is a unilateral soft tissue cephalometric landmark.

SignificanceSoft tissue subspinale is also used as one of the reference points in the construction of following planes in 3D cephalometric analysis.

Figure 17.4: Subnasale (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.5: Soft tissue subspinale (Image created with the Invivo5 software by Anatomage Inc.)

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Figure 17.6: Labrale superius (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.7: Stomion (Image created with the Invivo5 software by Anatomage Inc.)

Labrale Superius

AbbreviationLs–Labrale superius is abbreviated using English alphabets and is expressed as capital L followed by small s and is written continuously without any space between the alphabets.

DefinitionLabrale superius (Fig. 17.6) is the most anterior point on the margin of the upper membranous lip.

TypeLabrale superius is a unilateral soft tissue cephalometric landmark.

SignificanceLabrale superius is also used as one of the reference points in the construction of planes and angles in 3D cephalometric analysis.

Stomion

AbbreviationSto–Stomion is abbreviated using English alphabets and is expressed as capital S followed by small t and o and is written continuously without any space between the alphabets.

DefinitionStomion (Fig. 17.7) is the median point of the oral embrassure when the lips are closed.

TypeStomion is a unilateral soft tissue cephalometric landmark.

SignificanceStomion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Labrale Inferius

AbbreviationLi–Labrale inferius is abbreviated using English alphabets and is expressed as capital L followed by small i and is written continuously without any space between the alphabets.

Definition

Labrale inferius (Fig. 17.8) is the most anterior point on the lower margin of the lower membrane lip

TypeLabrale inferius is a unilateral soft tissue cephalometric landmark.


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SignificanceLabrale inferius is used as one of the reference point on the construction planes and angles in 3D cephalometric analysis.

Soft Tissue Submentale (Soft Tissue Point B)

AbbreviationB’–Soft tissue point B is abbreviated using English alphabet and is expressed as capital “B”.

DefinitionSoft tissue point B or soft tissue submentale (Fig. 17.9) is the point of greatest concavity in the midline of the lip between labrale inferius (Li) and soft tissue pogonion (Pog’ or Pogs).

TypeSoft tissue point B or soft tissue submentale is a unilateral soft tissue cephalometric landmark.

SignificanceSoft tissue point B is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Soft Tissue Pogonion

AbbreviationPogs or Pog’–Soft tissue pogonion is abbreviated using English alphabets and is expressed as capital P followed

Figure 17.8: Labrale inferius (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.9: Soft tissue point B (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.10: Soft tissue pogonion (Image created with the Invivo5 software by Anatomage Inc.)

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by small o and g with s in subscript position. It can also be denoted as Capital P followed by small o and g’ ending with ’ as a superscript.

DefinitionSoft tissue pogonion (Fig. 17.10) is the most prominent or anterior point on the soft tissue chin in the midsagittal plane.

TypeSoft tissue pogonion is a unilateral soft tissue cephalometric landmark.

SignificanceSoft tissue pogonion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Soft Tissue Gnathion

AbbreviationGns–Soft tissue gnathion is abbreviated using English alphabets and is expressed as capital G followed by small n with s in subscript position and is written continuously without any space between the alphabets.

DefinitionSoft tissue gnathion (Fig. 17.11) is the midpoint between the most anterior and inferior points of the soft tissue chin in the midsagittal plane.

TypeSoft tissue gnathion is a unilateral, constructed points, soft tissue cephalometric landmark.

SignificanceSoft tissue gnathion is used as one of the reference point on the construction planes and angles in 3D cephalometric analysis.

Orbitale

AbbreviationOrs–Orbitale is abbreviated using English alphabets and is expressed as capital O followed by small r with s in subscript position and is written continuously without any space between the alphabets.

DefinitionOrbitale (Fig. 17.12)—Most inferior portion of orbital floor below the center of eye.

TypeOrbitale is a bilateral soft tissue cephalometric landmark.

SignificanceOrbitale is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Figure 17.11: Soft tissue gnathion (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.12: Orbitale (Image created with the Invivo5 software by Anatomage Inc.)


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Zygomatic Prominence

AbbreviationZpS–Zygomatic prominence is abbreviated using English alphabets and is expressed as capital Z followed by small p with s in subscript position and is written continuously without any space between the alphabets.

DefinitionZygomatic prominence (Fig. 17.13)—Most protrusive anterior point on zygomatic arch.

TypeZygomatic prominence is a bilateral soft tissue cephalometric landmark.

SignificanceZygomatic prominence is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Zygion

AbbreviationZys–Zygion is abbreviated using English alphabets and is expressed as capital Z followed by small y with s in subscript position and is written continuously without any space between the alphabets.

DefinitionZygion (Fig. 17.14)–Most lateral point of each zygomatic arch eye.

TypeZygion is a unilateral soft tissue cephalometric landmark.

SignificanceZygion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Condylion

AbbreviationCos–Condylion is abbreviated using English alphabets and is expressed as capital C followed by small o with s in subscript position and is written continuously without any space between the alphabets.

DefinitionCondylion (Figs 17.15A and B)–Most superior midline point on condyle of mandible.

TypeCondylion is a bilateral soft tissue cephalometric landmark.

SignificanceCondylion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Figure 17.13: Zygomatic prominence (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.14: Zygion (Image created with the Invivo5 software by Anatomage Inc.)

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Gonion

Abbreviation

Gos–Gonion is abbreviated using English alphabets and is expressed as capital G followed by small o with s in subscript position and is written continuously without any space between the alphabets.

Definition

Gos (Figs 17.16A and B)—Most everted point of angle of mandible.

TypeGonion is a bilateral soft tissue cephalometric landmark.

SignificanceGonion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

ChAbbreviationCh—Ch is abbreviated using English alphabets and is expressed as capital C followed by small h written continuously without any space between the alphabets.

Figures 17.15A and B: Condylion (Image created with the Invivo5 software by Anatomage Inc.)

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Figures 17.16A and B: Gonion (Image created with the Invivo5 software by Anatomage Inc.)

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DefinitionCh (Fig. 17.17)–Most lateral border point of chin.

TypeCh is a unilateral soft tissue cephalometric landmark.

SignificanceCh is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Cheilion

AbbreviationC–Cheilion is abbreviated using English alphabet and is expressed as capital C.

DefinitionCheilion (Fig. 17.18)–Most lateral point located at each labial commissure.

TypeCheilion is a unilateral soft tissue cephalometric landmark.

SignificanceCheilion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Alare

AbbreviationAl–Alare is abbreviated using English alphabets and is expressed as capital A followed by small or lower case l and is written continuously without any space between the alphabets.

DefinitionAlare (Fig. 17.19)–The most lateral point on each alar contour.

Type

Alare is a bilateral soft tissue cephalometric landmark.

Significance

Alare is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Exocanthion

AbbreviationEx–Exocanthion is abbreviated using English alphabets and is expressed as capital E followed by small or lower case x and is written continuously without any space between the alphabets.

Figure 17.17: Ch (Image created with the Invivo5 software by Anatomage Inc.)

Figure 17.18: Cheilion (Image created with the Invivo5 software by Anatomage Inc.)

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DefinitionExocanthion–The point at the inner commissure of the eye tissue.

TypeExocathion is a bilateral soft tissue cephalometric landmark.

SignificanceExocathion is used as one of the reference points on the construction planes and angles in 3D cephalometric analysis.

Sella

AbbreviationS–Sella is abbreviated using English alphabet and is expressed as capital or upper case S.

DefinitionSella (Fig. 17.20) is the midpoint of sella turcica or hypophyseal fossa or pituitary fossa.

According to Robert E Moyers The center of the hypophyseal fossa (sella turcica). It is selected by the eye since that producer as been shown to be as reliable as a constructed center.

According to TM GraberThe center of pituitary fossa.

Figure 17.19: Alare (Image created with the Invivo5 software by Anatomage Inc.)

According to B Holly Broadbent Sella turcica (Turkish saddle). The landmark is the center of the sella as seen in the lateral radiograph and located by inspection.

According to LB HigleyThe center of sella turcica. The midpoint of the sella turcica arbitrarily determined.

According to William B Downs The center of sella turcica. Located by inspection of the profile image of the fossa.

According to Arne Bjork The center of sella turcica (the midpoint of the horizontal diameter).

TypeSella is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Sella on the Lateral CephalogramThe pituitary fossa is round and bottle shaped hollow space, situated in the upper body of the sphenoid bone. This fossa contains pituitary gland. This fossa is bounded anterioly and posteriorly by anterior and posterior clinoid processes. Both anterior and posterior clinoid process appears radio-opaque line on the lateral cephalogram. First trace the anterior and posterior clinoid process followed by inferior border of the pituitary fossa. Center point of the fossa is the point of sella.

Figure 17.20: Exocanthion (Image created with the Invivo5 software by Anatomage Inc.)


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Significance (Ref to Chapter 20) Sella is used as one of the reference points in the construction of angles and planes for the assessment of following:• Relationship of maxilla to cranial base is assessed using

SNA angle, S-N-Pr angle and saddle angle (N-S-Ar).• Relationship of mandible to cranial base is assessed using

SNB angle and S-N-Id angle.• Relationship of anterior and posterior cranial base assessed

using N-S-Ar.

Sella Entrance

AbbreviationSe–Sella entrance is abbreviated using English alphabets and is expressed as capital letter or upper case S followed by small letter or lower case e and is written continuously without any space between the alphabets.

DefinitionSella entrance (Fig. 17.21) is the mid entrance point of sella turcica or hypophyseal fossa or pituitary fossa.

TypeSella entrance is a unilateral, constructed, hard tissue cephalo-metric landmark.

Basion

AbbreviationBa–Basion is abbreviated using English alphabets and is denoted as capital letter or upper case B followed by small letter or lower case a and is written continuously without any space between the alphabets.

DefinitionBasion (Figs 17.22A to D) is the median point of the anterior margin of the foramen magnum can be located by following the images of the slope the inferior border of the basilar part of the occipital bone to its posterior limit.

According to Robert M RickettsPoint at the center of the anterior border of the foramen magnum at the base of the occipital bone.

According to TM GraberThe most inferior point on the anterior margin of the foramen magnum in the midsagittal plane.

According to Robert E MoyersThe most inferior posterior point in the sagittal plane on the anterior rim of the foramen magnum.

According to Arne BjorkNormal projection of the anterior border of the occipital foramen (endobasion) on the occipital foramen line.

According to Clifton T Forsberg The most anterior point relative to the interspinosum line, on the border of the foramen magnum.

TypeBasion is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing Basion on the Lateral Cephalogram• To identify basion on the lateral cephalogram, following

structures need to be traced.• Trace from the posterior cliniod process, down the upper

part of the clivus, and past the region of the spheno-Figure 17.21: Sella entrance (Image created with the Invivo5

software by Anatomage Inc.)

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Figures 17.22A to D: Basion (Image created with the Invivo5 software by Anatomage Inc.)

occipital synchondrosis to the anterior margin of the foramen magnum.

• Trace the cranial aspect of the greater wing of the sphenoid one, the inferior, ectocranial aspect of the base of the occipital bone, and the anterior margin of the foramen magnum. These are separate lines and should not be drawn a one continuous line.

• Trace carefully from the base of the occipital bone to the compact bone of the occipital condyles. The anterior margins of the occipital condyle and basion are radio-opaque on the lateral cephalogram and should be differentiated. Basion is usually behind the anterior part of the occipital condyle.

Anterior Nasal Spine

Abbreviation

ANS–Anterior nasal spine is abbreviated using English alphabets and is expressed as capital or upper case A, N and S, written continuously without any space between the alphabets.

Definition

Anterior nasal spine (Fig. 17.23) is the tip of bony anterior nasal spine in the midline or median plane.

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Figure 17.23: Anterior nasal spine (Image created with the Invivo5 software by Anatomage Inc.)

According to Viken SassouniThe most anterior point of the nasal floor tip of pre-maxilla on mid-sagittal plane.

According to B Holly BroadbentSharp median process formed by the forward prolongation of the anterior aperature of the nose.

According to TM Graber The tip of the anterior nasal spine as seen on the X-ray film in norma lateralis.

According to Robert E Moyers The most anterior point on the maxilla at the level of the palate. The ANS is of limited use for analysis in the posterior-anterior projection as the actual spine often cannot be seen and its location varies considerably according to radiographic exposure.

TypeAnterior nasal spine is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Anterior Nasal Spine on Lateral CephalogramThere exists an individual variation in length and width of ANS. In some individuals ANS are long and thin; while in other are short and thick.

Radiographic Appearance • ANS appears slightly posterior to the anatomic spine.• In cases with thin ANS–in such cases, on the cephalogram,

ANS will be unclear because it can superimpose by nasal cartilage.

• In cases with thick ANS–in such cases, on the cephalogram, ANS is clear and will be ease in tracing.

Significance (Ref to Chapter 20)Anterior nasal spine is used as one of the reference points in the construction of occlusal plane and is used for the assessment of horizontal growth pattern using FH-Palatal plane angle (ANS-PNS).

Section9PA Cephalometric

Landmarks

PA Cephalometric Landmarks

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Comprehensive cephalometric analysis systems have been developed to determine the lateral skeletal and dentoalveolar components of a malocclusion (Steiner, 1959; Ricketts, 1960). Approximately 90 percent of orthodontic practitioners in the USA make routine use of lateral cephalograms for every comprehensive case (Keim et al., 2002), illustrating the accepted value of lateral cephalometric analysis as an aid in orthodontic diagnosis and treatment planning. However, accurate diagnosis of discrepancies in width dimensions as well as of occlusal cants and asymmetries may also require a posteroanterior (PA) cephalometric evaluation.

Increases in transverse dental arch dimensions are associated with arch perimeter gain (Adkins et al., 1990). Bimaxillary expansion has therefore been recommended as a suitable alternative to premolar extraction, particularly in patients presenting with narrow dental arches (Cetlin and Ten Hoeve, 1983;Vanarsdall, 1999; McNamara et al., 2003; Ferris et al., 2005). However, that treatment decision should be based not only on dental arch measurements but also on suitable PA cephalometric analysis. The high prevalence of arch length deficiency and transverse malocclusions in different populations (Hill, 1992; Behbehani et al., 2005) may indicate that a considerable proportion of orthodontic patients may benefit from PA cephalometric evaluation. Several PA cephalometric analysis systems have been proposed (Sassouni, 1958;Letzer and Kronman, 1967; Ricketts et al., 1972; Hewitt, 1975; Svanholt and Solow, 1977; Grayson et al., 1983; Grummons and Kappeyne Van De Coppello, 1987). Of the two that are commercially available through the Dolphin® software (Ricketts et al., 1972; Grummons and Kappeyne Van De Coppello, 1987), only Ricketts’ analysis (Ricketts et al., 1972) is accompanied by a comprehensive set of norms, proposing age specific adjustments from adolescence to adulthood (Ricketts, 1981, Ricketts et al., 1982). However, the specific materials and methods used for calculating the norms have not been published. Grummons and Kappeyne Van De Coppello (1987) have presented a comprehensive analysis system for comparison of right and left triangular shapes, linear dimensions, and facial proportions. Since their purpose is to identify individual areas of asymmetry rather

than determining actual discrepancies, the analysis is not accompanied by normative data. The focus of the remaining analyses is to evaluate the skeletal and dental components of asymmetry through comparison of right and left triangular measurements (Letzer and Kronman, 1967; Hewitt, 1975), variables suitable for assessment of midline discrepancies (Svanholt and Solow, 1977; Grayson et al., 1983), or to determine the individual harmony of various proportions (Sassouni, 1958). Only a few of these analyses are supported by a limited set of normative data (Letzer and Kronman, 1967; Hewitt, 1975;Svanholt and Solow, 1977). Several well-known craniofacial growth studies include records suitable for transverse analyses. However, with the exception of select measurements of relatively small samples (Woods, 1950; Snodell et al., 1993; Cortella et al., 1997; Huertas and Ghafari, 2001; Hesby et al., 2006), normative data have been published only for 60 subjects without an ideal occlusion (Basyouni and Nanda, 2000). Athanasiou et al. (1992) provided norms for selected PA cephalometric measurements of 588 Austrian schoolchildren aged 6–15 years. Although the sample of adolescents was large, the inclusion of subjects without an ideal occlusion limits the validity of the findings. In addition, while Uysal and Sari (2005) provided PA cephalometric norms for adult Turks, analyzing a large sample with a Class I occlusion and pleasing facial morphology, no adolescents were included in their sample. Ethnic differences of clinical significance have been established in selected width measurements of Chinese relative to published data for Japanese and American Whites (Wei, 1970). Although the sample of Chinese was relatively large, only adults were included without occlusal selection criteria. In addition, similar differences have been established between Egyptians and other ethnic groups (Aboul-Azm and Korayem, 1987). The Egyptian sample was also limited to adults. Cephalometric norms should represent the means and ranges or clinically useful parameters from large samples of subjects of a similar age and ethnicity with untreated almost ideal occlusions to be valid as standards for comparison. According to these criteria, few of the existing data allow

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valid interpretations of skeletal versus dental components of malocclusions in the frontal plane, particularly for adolescent subjects. The aim of this study was to establish PA cephalometric norms for adolescent Kuwaitis of an age comparable with the normal start of comprehensive orthodontic treatment, and to compare these norms with those suggested in the available analysis systems as well as to other published information.

Taking Pa CephalogramThe PA cephalogram is taken with the patient’s head held straight (natural head position) or slightly down. The plane that intersects the ear rods, which help to stabilize the head, is known as the porionic, transporionic, or otic plane or axis because it presumably interacts with the external auditory meati.The film-object, film with ear rod, or porion-film distance determines the amount of magnification of the head structure. In early traditional cephalometry, the film holder was placed to touch the nose, and the percentage of magnification was computed and corrected. Later, the film-poronic axis distance could be set at a fixed distance (13-15 cm) with corresponding magnification factors. In digital machines, technological requirements dictate a greater sensor object distance (around 20 cm), leading to enlargement factors of more than 13 percent that can be corrected in the imaging software.

Structures Involved in Pa CephalogramFollowing structures are involved in PA cephalogram and need to be traced; Structures of right and left side need to be traced in PA cephalogram:• External peripheral cranial bone surfaces.• Coronal suture.• Mastoid processes.• Occipital condyles.• Planum sphenoidale and superior surface of the floor of

the pituitary fossa.• Floor of the nose.• Orbital outline and inferior surface of the orbital plate of

the frontal bone.• Oblique line formed by the external surface of the greater

wing of the sphenoid in the area of the temporal fossa.• Arcuate eminence .• Lateral surface of the frontosphenoidal process of the zygoma

and the zygomatic arch down to and including the key ridge• Cross-section of the zygomatic arch.• Infratemporal surface of the maxilla in the area of the

tuberosity, which is seen lateral to the lower outlines of the key ridge after the eruption of the permanent first molar.

• Body of the mandible.• Complete dentition or selected dental units.PA cephalometric landmarks/points related to specific bones are listed below:

1. Cephalometric landmarks (points) related to ethmoid bone.2. Cephalometric landmarks (points) related to nasal bone. 3. Cephalometric landmarks (points) related to zygomatic

bone. 4. Cephalometric landmarks (points) related to maxillary bone. 5. Cephalometric landmarks (points) related to dentition. 6. Cephalometric landmarks (points) related to mandible.

Pa Cephalometric Landmarks Related to Ethmoid BoneCephalometric landmark related to ethmoid bone are as follows (Table 18.1):

Table 18.1: Cephalometric landmark related to ethmoid bone

Cephalometric landmark Abbreviation Type Origin

Crista galli Nc Unilateral Anatomic

Crista galli

abbreviationNc–Crista galli is abbreviated using English alphabets and is expressed as capital letter or upper case N and small letter or lower case c and is written continuously without any space between the alphabets.

DefinitionNeck of crista galli (Figs 18.1A and B) is the neck of perpendicular lamina of the ethmoid.

according to Viken SassouniNeck of crista galli, most constricted point of the projection of the perpendicular lamina of the ethmoid (almost at the level of planum).

TypeNeck of crista galli is a unilateral, anatomic, hard tissue PA cephalometric landmark.

Pa Cephalometric Landmarks Related to Nasal Bone Cephalometric landmarks related to nasal bone are as follows (Table 18.2):

Table 18.2: Cephalometric landmarks related to nasal bone

Cephalometriclandmarks


top of nasal septum tns Unilateral Anatomic

NC NC Unilateral Anatomic

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Top of Nasal Septum

abbreviation

tns–Top of nasal septum is abbreviated using English alphabet and is expressed as small letter or lower case t, n, s and is written continuously without any space between the alphabets.

Definition

according to athanasios E athanasiouThe highest point onto the superior aspect of the nasal septum (Figs 18.2A and B).

TypeTop of nasal septum is a unilateral, anatomic, hard tissue PA cephalometric landmark.

Figures 18.1A and B: Crista galli

Figures 18.2A and B: Top of nasal septum

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NC

abbreviationNC–NC is abbreviated using English alphabets and is expressed as capital letter or upper case N, C and is written continuously without any space between the alphabets.

Definition

according to Robert M RickettsLateral most point on inside surface of the bony nasal cavity (Fig. 18.3).

TypeNC is a unilateral, anatomic, hard tissue PA cephalometric landmark.

Pa Cephalometric Landmarks Related to zygomatic BoneCephalometric landmarks related to zygomatic bone are as follows (Table 18.3): Table 18.3: Cephalometric landmarks related to zygomatic bone



Zygoma Zyg Bilateral Anatomic

Zygion Zy Bilateral Anatomic

Zygomatic arch ZA Bilateral Anatomic

Zygomatic suture point

Z Bilateral Anatomic

Jugal process J Bilateral Anatomic

zyg-zygoma

abbreviationZyg–Zygoma is abbreviated using English alphabet and is expressed as capital letter or upper case Z followed by lower case or small letter y, g and is written continuously without any space between the alphabets.

Definition

according to Viken SassouniMost lateral and superior point of the shadow of the zygomatic arch (Figs 18.4A and B).

Figure 18.3: NC

Figures 18.4A and B: Zygoma

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TypeZygoma is a bilateral, anatomic, hard tissue PA cephalometric landmark.

zygion

abbreviationZy–Zygion is abbreviated using English alphabets and is expressed as capital letter or upper case Z followed by lower case or small letter y and is written continuously without any space between the alphabets.

Definition

according to Robert M RickettsZygion is the most lateral point of each zygomatic arch (Figs 18.5A and B).

TypeZygion is a bilateral, anatomic, hard tissue PA cephalometric landmark.

zygomatic arch

abbreviationZA–Zygomatic arch is abbreviated using English alphabet and is expressed as capital letter or upper case Z, A and is written continuously without any space between the alphabets.

Definition

according to Robert M RickettsCenter of zygomatic arch by inspection for frontal (Figs 18.6A and B).

Figures 18.5A and B: Zygion

Figures 18.6A and B: Zygomatic arch

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TypeZygomatic arch is a bilateral, anatomic, hard tissue PA cephalo-metric landmark.

zygomatic Suture PointabbreviationZ–Zygomatic suture point is abbreviated using English alphabet and is expressed as capital letter or upper case Z.

Definition

according to Robert M RickettsMedial and anterior junction of the zygomatic bone with the frontal bone (Figs 18.7A and B).

TypeZygomatic suture point is a bilateral, anatomic, hard tissue PA cephalometric landmark.

Jugal Process

abbreviation

J–Jugal process is abbreviated using English alphabet and is expressed as capital letter or upper case J.

Definition

according to Robert M Ricketts

Lowest point on the curve of zygomatic bone used in the lateral film, also the point on the jugal process of the maxilla at a crossing with the tuberosity of the maxilla (in the frontal) (Figs 18.8A and B).

Type

Jugal process is a bilateral, anatomic, hard tissue PA cephalo-metric landmark.

Figures 18.7A and B: Zygomatic suture point

Figures 18.8A and B: Jugal process

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Pa Cephalometric Landmarks Related to MaxillaCephalometric landmarks related to maxilla is as follows (Table 18.4):Table 18.4: Cephalometric landmark related to maxilla

Cephalometric landmark Abbreviation Type Origin

Maxillare Mx or mx Bilateral Anatomic

MaxillareabbreviationMx–Maxillare is abbreviated using English alphabets and is expressed as capital letter or upper case M and small letter or lower case x and is written continuously without any space between the alphabets.

mx–Maxillare is also abbreviated using English alphabet and is expressed as small letter or lower case m, x and is written continuously without any space between the alphabets.

Definition• Maximum concavity on the contour of the maxilla between

the first molar and malare (Figs 18.9A and B).• Maximum concavity on the contour of the maxilla

between malare (Ma) and the maxillary first molar (U6).Closely corresponds to the key ridge.

• The intersection of the lateral contour of the maxillary alveolar process and the lower contour of the maxillozygomatic process of the maxilla (left and right).

TypeMaxillare is a bilateral, anatomic, hard tissue PA cephalometric landmark.

Pa Cephalometric Landmarks Related to DentitionPA cephalogram landmarks/points related to dentition are as follows (Tables 18.5 and 18.6):

Table 18.5: Cephalometric landmarks related to maxillary teeth


Incision superius incisalis Isi or is Unilateral Anatomic

Incision superius apicalis Isa or ULA Unilateral Anatomic

Maxillary molar um Bilateral Anatomic

Maxillary first molar U6 or A6 Bilateral Anatomic

Table 18.6: Cephalometric landmarks related to mandibular teeth


Incision inferior incisalis Iii or ii Unilateral Anatomic

Incision inferior apicalis Iia or LIA Unilateral Anatomic

Incision inferius frontale iif Unilateral Anatomic

Mandibular first molar L6 or A6 Bilateral Anatomic

mi mi Bilateral Anatomic

Mandibular molar Im Bilateral Anatomic

Incision Superius Incisalis

abbreviationIsi–Incision superius incisalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case s and i and is written continuously without any space between the alphabets.Or is–Incision superius is abbreviated using English alphabets and is expressed as small letters or lower case s and i and is written continuously without any space between the alphabets.

Figures 18.9A and B: Maxillare

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Definition Incision superius incisalis (Figs 18.10A and B) is the incisal edge of the maxillary central incisor.

according to arne Bjork Incision superius incisalis is the mid-point of the incisal edge of the most prominent upper central incisor.

according to Robert E MoyersIncision superius incisalis is the incisal tip of the most anterior maxillary central incisor.

TypeIncision superius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Superius Incisalis on Lateral CephalogramThe labial and lingual outline of the crown of the maxillary permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the maxillary permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of Incision Superius Incisalis.

Significance (Ref to Chapter 20)Incision superius incisalis is used as one of the reference point in the construction of angles and planes for the assessment of following:




• Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the NA plane.

• Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision Superius Incisalis and the A-Pog plane.

Incision Superius apicalis

abbreviation

Isa–Incision superius apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case s and a and is written continuously without any space between the alphabets.

UIA–Upper incisor apex is abbreviated using English alphabets and is expressed as capital or upper case U, I and A and is written continuously without any space between the alphabets.

DefinitionIncision superius apicalis (Figs 18.11A and B) is the root apex of the most anterior maxillary central incisor; if this

Figures 18.10A and B: Incision superius incisalis

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point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

according to Michael L RioloThe upper incisor apex is the root tip of the maxillary central incisor. In cases where the root is not yet completed, the midpoint of the growing root tip is marked.

SN Bhatia and BC LeightonThe upper incisor apex is the root apex of the most prominent upper incisor.

TypeIncision superius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Superius apicalis on Lateral CephalogramThe labial and lingual outline of the root of the maxillary permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the maxillary permanent central incisor. The point of intersection of labial and lingual outlines of the root of maxillary permanent central incisor is the point of Incision Superius Apicalis.

Significance (Ref to Chapter 20)Incision superius apicalis is used as one of the reference points in the construction of angles and planes for the assessment of following:




Maxillary Molar

abbreviation

um–Maxillary molar is abbreviated using English alphabets and is expressed as lower case u and m and is written continuously without any space between the alphabets.

Definition

according to athanasios E athanasiou

The most prominent lateral point on the buccal surface of the second deciduous or first permanent maxillary molar (Figs 18.12A and B).

Type

Maxillary molar is a bilateral, hard tissue cephalometric landmark.

Figures 18.11A and B: Incision superius apicalis

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Maxillary First Molar

abbreviationU6–Maxillary first molar is abbreviated using English alphabet and numeric and is expressed as capital or upper case U followed by English numeric 6 and is written continuously without any space between the alphabets.

ORA6—Maxillary first molar is abbreviated using English alphabet and numeric and is expressed as capital or upper case A followed by English numeric 6 and is written continuously without any space between the alphabets.

Figures 18.12A and B: Maxillary molar

Figures 18.13A and B: Maxillary first molar

A B

A B

DefinitionMaxillary first molar (Figs 18.13A and B) is the tip of the mesiobuccal cusp of the maxillary first permanent molar.

TypeMaxillary first molar is a bilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Maxillary First Molar on Lateral CephalogramThe labial and lingual and cuspal outlines of the crown of the maxillary permanent first molar appears as radio-opaque lines


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on the lateral cephalogram. Trace these outlines of crown of the maxillary permanent first molar, the tip of the mesiobuccal cusp of the maxillary permanent molar is the point of maxillary first molar.

Cuspid

abbreviationA3–Cuspid is abbreviated using English alphabet and numeric and is expressed as upper case A and numeric 3 and are written continuously without any space between the alphabets.

Definition

according to Carl F guginoTip of the upper permanent canine (Figs 18.14A and B).

TypeCuspid is a bilateral, hard tissue cephalometric landmark.

Incision Inferius Incisalis

abbreviation

Iii–Incision inferius incisalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case i and i and is written continuously without any space between the alphabets.

ii—Incision inferius is abbreviated using English alphabets and is expressed as small letters or lower case i and i and is written continuously without any space between the alphabets.

DefinitionIncision inferius incisalis (Figs 18.15A and B) is the incisal edge of the most prominent mandibular central incisor.

according to arne BjorkThe incision inferius is the incisal point of the most prominent medial mandibular incisor.

according to Robert E MoyersThe incision inferius is the incisal tip of the most labial mandibular central incisor.

TypeIncision inferius incisalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Inferius Incisalis on Lateal Cephalogram

The labial and lingual outline of the crown of the mandibular permanent central incisor appears as radio-opaque line on the lateral cephalogram. Trace these two outlines of crown of the mandibular permanent central incisor. The tip of the incisal edge or the intersection of the labial and lingual outline is the point of incision inferius incisalis.

Significance (Ref to Chapter 20)Incision inferius incisalis is used as one of the reference point in the construction of angles and planes for the assessment of following:

Figures 18.14A and B: Cuspid

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• Inclination of lower incisor is assessed using angle drawn between the Long axis of lower incisor plane and the mandibular plane.


• Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisorl.

• Anteroposterior positioning of mandibular central incisor is assessed using the distance between the incision inferius Incisalis and the NB plane.

• Anteroposterior positioning of maxillary central incisor is assessed using the distance between the incision inferius incisalis and the A-Pog plane.

Incision Inferius apicalis

abbreviationIia–Incision inferius apicalis is abbreviated using English alphabets and is expressed as capital or upper case I followed by small letters or lower case i and a and is written continuously without any space between the alphabets.LIA–lower incisor apex is abbreviated using English alphabets and is expressed as capital or upper case L, I and A and is written continuously without any space between the alphabets.

DefinitionIncision inferius apicalis (Figs 18.16A and B) is the root apex of the most anterior mandibular central incisor; if this

Figures 18.16A and B: Incision inferius apicalis

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point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

SN Bhatia and BC Leighton The lower incisor apex is the root apex of the most prominent lower incisor.

TypeIncision inferius apicalis is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Incision Inferius apicalis on Lateal CephalogramThe labial and lingual outline of the root of the mandibular permanent central incisor appears as radio-opaque lines on the lateral cephalogram. Trace these two outlines of root of the mandibular permanent central incisor. The point of intersection of labial and lingual outlines of the root of mmandibular per-manent central incisor is the point of incision inferius apicalis.

Significance (Ref to Chapter 20)Incision inferius apicalis is used as one of the reference point in the construction of angles and planes for the assessment of following:• Inclination of lower incisor is assessed using angle drawn

between the long axis of upper incisor plane and the mandi-bular plane.


• Inter-incisal relationship of upper and lower incisors are assessed using the angle drawn between the long axis of upper and lower permanent central incisors.

Incision Inferius Frontale

abbreviation

iif–Incision inferius frontale is abbreviated using English alphabets and is expressed as lower case i, i and f and is written continuously without any space between the alphabets.

Definition

according to athanasios E athanasiou

The midpoint between the mandibular central incisors at the level of the incisal edges (Figs 18.17A and B).

Type

Incision inferius frontale is a unilateral, hard tissue cephalo-metric landmark.

Mandibular First Molar

abbreviation

L6–Mandibular first molar is abbreviated using English alphabet and numeric and is expressed as capital or upper case L followed by English numeric 6 and is written continuously without any space between the alphabets.

Definition

Mandibular first molar (Figs 18.18A and B) is the tip of the mesiobuccal cusp of the mandibular first permanent molar.

Figures 18.17A and B: Incision inferius frontale

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TypeMandibular first molar is a unilateral, anatomic, hard tissue cephalometric landmark.

Tracing of Mandibular First Molar on Lateral CephalogramThe labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar.

mi

abbreviationmi–mi is abbreviated using English alphabets and is expressed as lower case m and i and is written continuously without any space between the alphabets.

Figures 18.18A and B: Mandibular first molar

Figures 18.19A and B: mi

A B

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Definition mi (Figs 18.19A and B) is the mesial contact of the lower molar projected normal to the plane of occlusion.

Typemi is a bilateral, hard tissue cephalometric landmark.

Tracing of mi on Lateral CephalogramThe labial and lingual and cuspal outlines of the crown of the mandibular permanent first molar appears as radio-opaque lines on the lateral cephalogram. Trace these outlines of crown of the mandibular permanent first molar, the tip of the mesiobuccal cusp of the mandibular permanent molar is the point of maxillary first molar. mi is the mesial contact of the lower molar projected normal to the plane of occlusion.

Significance (Ref to Chapter 20)mi is used as one of the reference points in the construction of plane and angle in the Bjork cephalometric analysis.


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Mandibular Molar

abbreviationIm–Mandibular molar is abbreviated using English alphabets and is expressed as upper case I and lower case m and is written continuously without any space between the alphabets.

Definition

according to athanasios E athanasiouThe most prominent lateral point on the buccal surface of the second deciduous or first permanent mandibular molar (Figs 18.20A and B).

Type

Mandibular molar is a bilateral, hard tissue cephalometric landmark.

Pa Cephalometric Landmarks Related to MandibleCephalometric landmarks related to mandible are as follows (Table 18.6):

Table 18.6: Cephalometric landmarks related to mandible


Menton Me Unilateral Anatomic

Articulare Ar Bilateral Anatomic

Malare ma Bilateral Anatomic

Antegonial tubercle Ag Bilateral Anatomic

Antegonion Ag Bilateral Anatomic

Menton

abbreviationMe–Menton is abbreviated using English alphabets and is expressed as capital or upper case M followed by lower case or small letter e and is written continuously without any space between the alphabets.

according to Viken SassouniLower most point of the contour of the chin.

according to Carl F guginoMenton (Figs 18.21A and B) is the point on inferior border of symphysis directly inferior to mental protuberance and below center of trigonium mentali.

Figures 18.20A and B: Mandibular molar

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TypeMenton (see Figs 12.7A and B) is a unilateral, anatomic, hard tissue landmark.

Tracing of Menton on the Lateral CephalogramThe labial cortical plate of mandible in the anterior symphysis region appears as vertical shaped radio-opaque line. Trace the labial cortical plate from the alveolar crest between two permanent mandibular incisors in the midline to the point anteroinferior point on the mandible. Below the point B follows the convex outline of labial cortical plate of mandible,the most prominent point is the point of pogonion.The anteroinferior point of inferior border of the mandible in the midline is the point of menton.

SignificanceMenton is used as one of the reference points in the construction of plane and angle for the assessment of the following:• Constructions of mandibular plane, i.e. the line joining the




(APocc – PPocc ) to mandibular plane (Me-Go) angle.• Growth pattern is assessed using Go1 and Go2 angles.

articulare

abbreviationAr–Articulare is abbreviated using English alphabets and is expressed as capital or upper case A followed by lower case

Figures 18.21A and B: Menton

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or small letter r and is written continuously without any space between the alphabets.

DefinitionArticulare (Figs 18.22A and B) is the point of intersection the dorsal contours of the processus articularis mandibulare and os tempoarle.The midpoint, a is used where double projection gives rise to two points a1 and a2.

TypeArticulare is a bilateral, anatomic, hard tissue landmark.

Tracing of articulare on the Lateral CephalogramThe posterior or ramus border of the mandible appears as radio-opaque line on the lateral cephalogram. Trace ramus border of the mandible. The point on the ramus border of the mandible at the neck region.

SignificanceArticulare is used as one of the reference points in the construction of plane and angle for the assessment of following:• Constructions of posterior/ramus border of the mandible

i.e. the line joining the point articulare and gonion.• Growth pattern is assessed using Go1 and Go2 angles.• Rotation of the mandible is also assessed using the S-Ar-

Go angle.

Malare

abbreviation ma–Malare is abbreviated using English alphabets and is expressed as lower case or small letters m, a and is written continuously without any space between the alphabets.


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Figures 18.22A and B: Articulare

Definition

according to Viken SassouniMidpoint of intersection between the projection of the coronoid process and the lower contour of the malar bone(Figs 18.23A and B).

TypeMalare is a bilateral, anatomic, hard tissue PA cephalometric landmark.

antegonial Tubercles

abbreviationAg–Antegonial tubercles are abbreviated using English alphabets and is expressed as upper case or capital letter A and lower case or small letters g and is written continuously without any space between the alphabets.

Definition

according to Robert M RickettsIntersection of the outline of the dense bone of the trihedral eminence with the lower border of the ramus. (Figs 18.24A and B).

TypeAntegonial tubercle is a bilateral, anatomic, hard tissue PA cephalo metric landmark.

antegonion

abbreviation

Ag–Antegonion is abbreviated using English alphabets and is expressed as upper case or capital letter A and lower case or small letter g and is written continuously without any space between the alphabets.

Figures 18.23A and B: Malare

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Figures 18.24A and B: Antegonial tubercles

Figures 18.25A and B: Antegonion

Definition

according to athanasios E athanasiouThe highest point in the antegonial notch (left and right) (Figs 18.25A and B).

TypeAntegonion is a bilateral, anatomic, hard tissue PA cephalo-metric landmark.

A B

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SECTION10SV Cephalometric

Landmarks

SV Cephalometric Landmarks

CH

AP

TE

R

19 SV Cephalometric Landmarks

Figures 19.1A and B: Basion

Basion

AbbreviationBa–Basion is abbreviated as capital or upper case B followed by small letter or lower case a and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergBasion is the most anterior point, relative to the interspinosum line, on the border of the foramen magnum (Figs 19.1A and B).

TypeBasion is a unilateral hard tissue SV cephalometric landmark/point.

OriginBasion is an anatomic SV cephalometric landmark/point.

Opisthion

AbbreviationOp–Opisthion is abbreviated as capital or upper case O followed by small letter or lower case p and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergOpisthion is the most posterior point, relative to the interspinosum line, on the border of the foramen magnum (Figs 19.2A and B).

Type Opisthion is a unilateral hard tissue SV cephalometric landmark/point.

OriginOpisthion is an anatomic SV cephalometric landmark/point.

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Figures 19.2A and B: Opisthion

Figures 19.3A and B: Foramina spinosa points

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Foramina Spinosa Points

Abbreviation

FSP–Foramina spinosa point is abbreviated as capital or upper case F, S and P and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergForamina spinosa points are the geometric center of each foramina spinosa (Figs 19.3A and B).

Type Foramina spinosa points are bilateral hard tissue SV cephalometric landmarks/points.

Origin Foramina spinosa points are an anatomic SV cephalometric landmarks/points.

Foramina Spinosum

AbbreviationSP–Foramina spinosum is abbreviated as capital or upper case S and P and is written continuously without any space between the alphabets.

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Definition

According to KKK LewThe geometric center of each foramen spinosum (Figs 19.4A and B).

Type Foramina spinosum points are bilateral hard tissue SV cephalometric landmarks/points.

OriginForamina spinosum points are an anatomic SV cephalometric landmarks/points.

Odontoid

AbbreviationOd–Odontoid is abbreviated as capital letter or upper case O and followed by small letter or lower case d and is written continuously without any space between the alphabets.

Definition

According to KKK LewCenter of odontoid process on the SMV (Figs 19.5A and B).

Figures 19.4A and B: Foramina spinosum

Figures 19.5A and B: Odontoid

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Type Odontoid is a unilateral hard tissue SV cephalometric landmark/point.

OriginOdontoid is an anatomic SV cephalometric landmark/point.


AbbreviationPTM–Pterygomaxillary fissure is abbreviated as capital letter or upper case P, T and M and are written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe most medial and posterior point of each pterygomaxillary fissure. The PTM line connects the right and left PTM points. The PTM axis is the perpendicular bisector of the PTM line (Figs 19.6A and B).

TypePterygomaxillary fissure is a bilateral hard tissue SV cephalometric landmark/point.

OriginPterygomaxillary fissure is an anatomic SV cephalometric landmark/point.

Middle Cranial Fossa Points

AbbreviationMCF–Middle cranial fossa point is abbreviated as capital letters or upper case MCF and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe most anterior point relative to the interspinosum line, on each lesser wing of the sphenoid bone (LWS) (Figs 19.7A and B).

TypeMiddle cranial fossa points is a bilateral hard tissue SV cephalometric landmark/point.

OriginMiddle cranial fossa point is an anatomic SV cephalometric landmark/point.

Posterior Vomer Point

AbbreviationPVP–Posterior vomer point is abbreviated as capital letter or upper case PVP and is written continuously without any space between the alphabets.

Figures 19.6A and B: Pterygomaxillary fissure

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Definition

According to Clifton T Forsberg

The intersection of the vomer with the PTM line (Figs 19.8A and B).

Type

Posterior vomer point is a unilateral hard tissue SV cephalometric landmark/point.

OriginPosterior vomer point is an anatomic SV cephalometric landmark/point.

Figures 19.7A and B: Middle cranial fossa points

Figures 19.8A and B: Posterior vomer point

Posterior Cranial Vault Points

AbbreviationPCV–Posterior cranial vault points is abbreviated as capital letter or upper case PVP and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe intersections of the lateral borders of the cranial vault with a line, parallel to the interspinosum line, which is drawn across the cranial vault at its section of greatest width (Figs 19.9A and B).

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Figures 19.9A and B: Posterior cranial vault points

Figures 19.10A and B: Angulare point

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TypePosterior cranial vault points are bilateral hard tissue SV cephalometric landmark/point.

Origin Posterior cranial vault point is an SV anatomic cephalometric landmark/point.

Angulare Point

AbbreviationA–Angulare point is abbreviated as capital letter or upper case A.

Definition

According to Clifton T ForsbergThe most anterior point, relative to the PTM line, of the triangular opacities present at the external orbital angle where the upper and lower orbital rims meet and the zygomatic arch inserts (Figs 19.10A and B).

TypeAngulare point is a bilateral hard tissue SV cephalometric landmark/point.

OriginAngulare point is an anatomic SV cephalometric landmark/ point.

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Maxillary Apical Base Midline

AbbreviationMAB–Maxillary apical base midline is abbreviated as capital letter or upper case MAB.

Definition

According to Clifton T ForsbergA point midway between the roots of the maxillary central incisors at a level which is one third of the distance from the apex of the tooth to the alveolar crest. This point is determined on the PA radiograph and its position is then transferred to the SV radiograph in its proper position relative to the dental midline (Figs 19.11A and B).

TypeMaxillary apical base midline is a unilateral hard tissue SV cephalometric landmark/point.

OriginMaxillary apical base midline is an anatomic SV cephalometric landmark/point.

Mandibular Dental Midline

AbbreviationMand DM–Mandibular dental midline is abbreviated as Mand DM.

Definition

According to Clifton T ForsbergThe point contact between the mesial surfaces of the crowns of the mandibular central incisors (Figs 19.12A and B).

TypeMandibular dental midline is a unilateral hard tissue SV cephalometric landmark/point.

OriginMandibular dental midline is an anatomic SV cephalometric landmark/point.

Figures 19.11A and B: Maxillary apical base midline

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Mandibular Apical Base Midline

AbbreviationMAB–Mandibular apical base midline is abbreviated as capital letter or upper case MAB.

Definition

According to Clifton T ForsbergA point midway between the roots of the mandibular central

incisors at a level which is one third of the distance from the apex to the alveolar crest (Figs 19.13A and B).

TypeMandibular apical base midline is a unilateral hard tissue SV cephalometric landmark/point.

OriginMandibular apical base midline is an anatomic SV cephalometric landmark/point.

Figures 19.13A and B: Mandibular apical base midline

Figures 19.12A and B: Mandibular dental midline

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First Molar Point

AbbreviationFMP–First molar point is abbreviated as capital letter or upper case FMP and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe most distal point in line with the central groove on each mandibular first molar (Figs 19.14A and B).

TypeFirst molar point is a bilateral hard tissue SV cephalometric landmark/point.

OriginFirst molar point is an anatomic SV cephalometric landmark/ point.

Gonion Point

AbbreviationGo–Gonion point is abbreviated as capital letter or upper case G followed by small letter or lower case o and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe midpoint mediolaterally on the posterior border of each gonial angle (Figs 19.15A and B).

Figures 19.14A and B: First molar point

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Figures 19.15A and B: Gonion point

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TypeGonion point is a bilateral hard tissue SV cephalometric landmark/point.

OriginGonion point is an anatomic SV cephalometric landmark/ point.

Condylion Medialis

AbbreviationCM–Condylion medialis is abbreviated as capital letter or upper case CM and is written continuously without any space between the alphabets.

ORCoM–Condylion medialis is abbreviated as capital letter or upper case C, small letter o followed by capital letter M and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe tangent point to each medial condylar border of a line drawn parallel to each mandibular body line (Figs 19.16A and B).

TypeCondylion medialis is a bilateral hard tissue SV cephalometric landmark/point.

OriginCondylion medialis is an anatomic SV cephalometric landmark/point.

Condylion Lateralis

AbbreviationCL–Condylion lateralis is abbreviated as capital letter or upper case CL and is written continuously without any space between the alphabets.

OrCoL–Condylion lateralis is abbreviated as capital letter or upper case C, small letter o followed by capital letter L and is written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergThe tangent point to each lateral condylar border of a line drawn parallel to each mandibular body line (Figs 19.17A and B).

Type Condylion lateralis is a bilateral hard tissue SV cephalometric landmark/point.

OriginCondylion lateralis is an anatomic SV cephalometric landmark/point.

Figures 19.16A and B: Condylion medialis

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Condylion Anterioris

AbbreviationCA–Condylion anterioris is abbreviated as capital letter or upper case C and A, and is written continuously without any space between the alphabets.

Figures 19.17A and B: Condylion lateralis

Definition

According to Clifton T Forsberg

A point on the anterior of each condylar head which is chosen to represent the mandibular fossa of the temporal bone (Figs 19.18A and B).

A B

Figures 19.18A and B: Condylion anterioris

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TypeCondylion anterioris is a bilateral hard tissue SV cephalometric landmark/point.

OriginCondylion anterioris is an anatomic SV cephalometric landmark/point.

Condylion Posterioris

AbbreviationCP–Condylion posterioris is abbreviated as capital letter or upper case C, P and are written continuously without any space between the alphabets.

Definition

According to Clifton T ForsbergA point on the posterior of each condylar head which is chosen to represent the mandibular fossa of the temporal bone (Figs 19.19A and B).

TypeCondylion posterioris is a bilateral hard tissue SV cephalometric landmark/point.

OriginCondylion posterioris is an anatomic SV cephalometric landmark/point.

Figures 19.19A and B: Condylion posterioris

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SECTION11Applications of Cephalometric

Landmarks

ApplicationsofCephalometricLandmarks

CHAPTER

20 Applications of Cephalometric Landmarks

Cephalometric Landmarks (Points) used in various cephaloemtric analyses are listed below: 1. Bjork cephalometric analysis 2. Coben craniofacial and dentition analysis 3. Downs cephalometric analysis 4. Farkas and Coworkers soft tissue cephalometric analysis 5. Harvold cephalometric analysis 6. Holdaway cephalometric analysis 7. Legan and burstone soft tissue cephalometric analysis 8. Rickett’s cephalometric analysis 9. Sassouni cephalometric analysis 10. Di Paolo’s quadrilateral cephalometric analysis 11. Hasund (Bergen) cephalometric analysis 12. Jarabak cephalometric analysis 13. Riedel cephalometric analysis 14. Schwartz cephalometric analysis 15. Wylie cephalometric analysis 16. Steiner’s cephalometric analysis

17. Tweed’s cephalometric analysis 18. Wit’s cephalometric analysis 19. Basis cephalometric analysis 20. Cagliari cephalometric analysis 21. Chieti cephalometric analysis 22. McGann cephalometric analysis.

Bjork Cephalometric Analysis (Figs 20.1A and B)Cephalometric landmarks used in Bjork cephalometric analysis are as given below:

Ar-articulare–The point of intersection of the dorsal contours of processus articularis mandibulae and os temporale. The midpoint is used where double projection gives rise to two articulare points.

dd–The most prominent point of the chin in the direction of measurement.

gn-gnathion–The deepest point on the chin.

Figures 20.1A and B: Bjork cephalometric analysis

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id-infradentale–The point of transition from the crown of the most prominent mandibular medial incisor to the alveolar projection.

ii-incision inferius–The incisal point of the most prominent medial mandibular incisor.

is-incision superius–The incisal point of the most prominent medial maxillary incisor.

kk–The point of intersection between the base and ramus tangents to the mandible. The midpoint is used where double projection gives rise to two points.

mi–The mesial contact point of the lower molar projected normal to the plane of occlusion.

ms–The mesial contact point of the upper molar projected normal to the plane of occlusion.

N-nasion–Nasion is the most anterior point of the frontonasal suture in the middle.

or-orbitale–The deepest point on the infraorbital margin. The midpoint is used where double projection gives rise to two points.

pg-pogonion–The most prominent point on the chin.

Po-porion–Porion is the most superior point of the external auditory meatus (the superior margin of the TMJ fossa, which lies at the same level may be substitute in the construction of the FH).

pr-prosthion–The transition point between the crown of the most prominent medial maxillary incisor and the alveolar projection.

s–The center of sella turcica (the midpoint of the horizontal diameter).

sm-supramentale–The deepest point on the contour of the alveolar projection, between infradentale and pogonion.

sp-the spinal point–The apex of spina nasalis anterior.

snp-spina nasalis posterior–The point of intersection of palatum posterior durum, palatum molle and fossa pterygopalatina.

ss-subspinale–The deepest point on the contour of the alveolar projection, between the spinal point and prosthion.

io–The incisal point of the most prominent medial mandibular incisor, projected normal to the plane of occlusion.

Coben Craniofacial and Dentition Cephalometric Analysis (Figs 20.2A and B)Cephalometric landmarks used in Coben craniofacial and dentition analysis are as given below:

A-point A (subspinale)–The point at the deepest midline concavity on the maxilla between the anterior nasal spine and prosthion.

Ans-anterior nasal spine–The most anterior point of the anterior nasal spine.

Ar-articulare–The point of intersection of the images of the posterior border of the condylar process of the mandible and the inferior border of the basilar part of the occipital bone.

B-point B (supramentale)–The point at the deepest midline concavity on the mandibular symphysis between infradentale and pogonion.

Figures 20.2A and B: Coben craniofacial and dentition analysis

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Ba–Basion is the median point of the anterior margin of the foramen magnum can be located by following the images of the slope of the inferior border of the basilar part of the occipital bone to its posterior limit.

F-point F (constructed)–The point approximating foramen cecum representing the anatomic anterior limit of the cranial base, constructed as the point of intersection of a perpendicular to the SN plane from the point of crossing of the images of the orbital roofs and the internal plate of the frontal bone.

Go-gonion (constructed)–The point of intersection of the ramus plane and the mandibular plane.

M-menton–The most inferior midline point on the mandibular symphysis.


Or-orbitale–The lowest point on the inferior margin of the orbit, midpoint between right and left images.

Po-porion (anatomic)–The superior point of the externaLauditory meatus (superior margin of temporomandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).

Pog-pogonion–The most anterior midline point of the mandibular symphysis.

Po’-pogonion’ (constructed)–The point of tangency of a perpendicular from the mandibular plane to the most prominent convexity of the mandibular symphysis.

Ptm-pterygomaxillary fissure–The point of intersection of the images of the anterior surface of the pterygoid process of the sphenoid bone and the posterior margin of the maxilla.

S-sella–The point representing the geometric center of the pituitary fossa (sella turcica).

Ul-maxillary central incisor (horizontal)–The most labial point on the crown of the maxillary central incisor.

Ul-maxillary central incisor (vertical)–The incisal edge of the maxillary central incisor.

L1-mandibular central incisor (horizontal)–The most labial point on the crown of the mandibular central incisor.

L1-mandibular central incisor (vertical)–The incisal edge of the mandibular central incisor.

U6-maxillary first molar (horizontal)–The most distal point on the crown of the maxillary first permanent molar.

U6-maxillary first molar (vertical)–The tip of the mesiobuccal cusp of the maxillary first permanent molar.

L6-mandibular first molar (horizontal)–The most distal point on the crown of the mandibular first permanent molar.

L6-mandibular first molar (vertical)–The tip of the mesiobuccal cusp of the mandibular first permanent molar.

Downs Cephalometric Analysis (Figs 20.3A and B)

Cephalometric landmarks used in Downs cephalometric analysis are as given below:

Figures 20.3A and B: Downs cephalometric analysis

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Bolton point–The highest point on the concavity behind the occipital condyles.

The centre of sella turcica–Located by inspection of the profile image of the fossa.

Orbitale–The lowest point on the left infraorbital margin.

Porion (cephalometric)–The highest point on the superior surface of the soft tissue of the external auditory meati.

Pogonion–The most anterior point on the mandible in the midline.

Point A-subspinale–The deepest midline point on the premaxilla between the anterior nasal spine and prosthion.

Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion.

Gnathion–A point on the chin determined by bisecting the angle formed by the facial and mandibular planes.

Farkas and Coworkers Soft Tissue Cephalometric Analysis (Figs 20.4A and A)

Cephalometric landmarks used in Farkas and Coworkers soft tissue cephalometric analysis are as given below:

Trichion (tr)–Point on the hairline in the midline of the forehead.

Glabella (g)–The most prominent midline point between the eyebrows.

Subnasion (n’)–Deepest point of the nasofrontal angle.

Pronasale (prn)–The most protruded point of the apex nasi.

Subnasale (sn)–Midpoint of the columella base at the apex of the nasolabial angle.

Labiale superius (ls)–Midpoint of the upper vermilion line.

Labiale inferius (li)–Midpoint of the lower vermilion line.

Sublabiale (si)–Midpoint of the horizontal labiomental skin ridge.

Pogonion (pg)–The most anterior midpoint of the chin.

Harvold Cephalometric Analysis (Figs 20.5A and B)Cephalometric landmarks used in Harvold cephalometric analysis are as given below:

Temporomandibular joint (TMJ)–A point on the contour of the glenoid fossa, where the line indicating the maximum length of the mandible intercepts the contour of the temporomandibular fossa. The midpoint between the right and left side is marked.

Anterior nasal spine (ANS)–A point on the lower contour of the anterior nasal spine where the vertical thickness is 3 mm, used for horizontal measurements; a point on the upper contour of the anterior nasal spine, where the vertical thickness is 3 mm, employed for vertical measurements.

Figures 20.4A and B: Farkas and coworkers soft tissue cephalometric analysis

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Prognathion (PGN)–A point on the contour of the chin indicating maximum mandibular length measured from the temporomandibular joint.

Gnathion (GN)–The most inferior point on the contour of the chin.

Pogonion (PG)–The most anterior point on the chin.

Nasion (N)–The point at which the nasofrontal suture reaches the contour line of the bones. The forward position of the maxilla, measured from TM to ANS.

Mandibular length measured from TM to PGN.

Lower face height measured from ANS to GN.

The angle of convexity–The angle between the lines PGANS and ANSN.

Holdaway Cephalometric Analysis (Figs 20.6A and B)Cephalometric landmarks used in Holdaway cephalometric analysis are as given below: 1. The H line or harmony line drawn tangent to the soft

tissue chin and the upper lip.

Figures 20.5A and B: Harvold cephalometric analysis

Figures 20.6A and B: Holdaway cephalometric analysis

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2. A soft tissue facial line from softtissue nasion to the point on the soft tissue chin overlying Rickett’s suprapogonion.

3. The usual hard tissue facial plane. 4. The sellanasion line. 5. Frankfort horizontal plane (FH). 6. A line running at a right angle to the Frankfort plane

down tangent to the vermilion border of the upper lip.

Legan and Burstone Soft Tissue Cephalometric Analysis (Figs 20.7A and B)Cephalometric landmarks used in Legan and Burstone soft tissue cephalometric analysis are as given below:

Glabella (G)–The most prominent point in the midsagittal plane of the forehead.

Columella point (Cm)–The most anterior point on the columella of the nose.

Subnasale (Sn)–The point at which the nasal septum merges with the upper cutaneous lip in the midsagittal plane.

Labrale superius (Ls)–A point indicating the mucocutaneous border of the upper lip.

Stomion superius (Stms)–The lowermost point on the vermilion of the upper lip.

Stomion inferius (Stmi)–The uppermost point on the vermilion of the lower lip.

Labrale inferius (Li)–A point indicating the mucocutaneous border of the lower lip.

Mentolabial sulcus (Si)–The point of greatest concavity in the midline between the lower lip (Li) and chin (Pg’).Soft tissue pogonion (Pg’)–The most anterior point on soft tissue chin.Soft tissue gnathion (Gn’)–The constructed midpoint between soft tissue pogonion and soft tissue menton; can be located at the intersection of the subnasale to soft tissue pogonion line and the line from C to Me.Soft tissue menton (Me’)–The lowest point on the contour of the soft tissue chin; found by dropping a perpendicular from horizontal plane through menton.Cervical point (C)–The innermost point between the submental area and the neck located at the intersection of lines drawn tangent to the neck and submental areas.

Rickett’s Cephalometric Analysis (Figs 20.8A and B)Cephalometric landmarks used in Rickett’s cephalometric analysis are as given below:

A–The deepest point on the curve of the maxilla between the anterior nasal spine and the dental alveolus.

ANS–Tip of the anterior nasal spine.

BA–Most inferior posterior point of the occipital bone.

CC–Point where the basionnasion plane and the facial axis intersect.

DC–A point selected in the center of the neck of the condyle, where the basionnasion plane crosses it.

Figures 20.7A and B: Legan and Burstone soft tissue cephalometric analysis

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NA–A point at the anterior limit of the nasofrontal suture.

PM–Point selected at the anterior border of the symphysis between point B and pogonion where the curvature changes from concave to convex.

PO–Most anterior point on the midsagittal symphysis tangent to the facial plane.

XI–The geometric center of the ramus of the mandible.

Sassouni Cephalometric Analysis (Fig. 20.9)Cephalometric landmarks used in Sassouni cephalometric analysis are as given below:

Palatocranial angle–Angle formed by the palatal plane and the anterior cranial base plane.

Palatomandibular angle–Angle formed by the palatal plane and the mandibular base plane.

Occlusopalatal angle–Angle formed by the occlusal plane and the palatal plane.

Occlusomandibular angle–Angle formed by the occlusal plane and the mandibular base plane.

Angle M–Angle formed by the 6 axis and the occlusal plane.

Angle M’ –Angle formed by the 6 axis and che palatal plane.

Angle M”–Angle formed by the 6 axis and the anterior cranial base plane.

Angle I–Angle formed by 1 and the occlusal plane.

Figures 20.8A and B: Rickett’s cephalometric analysis

Figure 20.9: Sassouni cephalometric analysis

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Angle I’–Angle formed by i and the palatal plane.

Angle I”–Angle formed by I and che ancerior cranial base plane.

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Angle R–Angle formed by the occlusal plane and the ramal plane.

Angle i–Angle formed by the occlusal plane and the axis of 1.

Angle rfl’–Angle formed by the occlusal plane and the axis of 6.

Di Paolo’s Quadrilateral Analysis (Fig. 20.10)Cephalometric landmarks used in Di Paolo’s Quadrilateral cephalometric analysis are as given below:

A–The deepest point on the curve of the maxilla between the anterior nasal spine and the dental alveolus.

ANS–Tip of the anterior nasal spine.

Nasion (N)–The point at which the nasofrontal suture reaches the contour line of the bones.



Ptm-pterygomaxillary fissure–The point of intersection of the images of the anterior surface of the pterygoid process of the sphenoid bone and the posterior margin of the maxilla.


Figure 20.10: Di Paolo’s quadrilateral cephalometric analysis Figure 20.11: Hasund (Bergen) cephalometric analysis

Ar-articulare–The point of intersection of the dorsal contours of processus articularis mandibulae and os temporale. The midpoint is used where double projection gives rise to two articulare points.


Hasund (Bergen) Cephalometric Analysis (Fig. 20.11)Cephalometric landmarks used in Hasund (Bergen) cephalometric analysis are as given below:



Ar-articulate–The point of intersection of the images of the posterior border of the condylar process of the mandible and the inferior border of the basilar part of the occipital bone.



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Ba-basion–The median point of the anterior margin of the foramen magnum located by following the image of the slope of the inferior border of the basilar part of the occipital bone to its posterior limit.

N-nasion–The most anterior (midline) point of the frontonasal suture.

S-sella–The point representing the geometric centrer of the pituitary fossa (sella turcica).





Jarabak Cephalometric Analysis (Figs 20.12A and B)Cephalometric landmarks used in Jarabak cephalometric analysis are as given below:



Ar-articulare–The point of intersection of the images of the posterior border of the condylar process of the mandible and the inferior border of the basilar part of the occipital bone.


Ba-basion–The median point of the anterior margin of the foramen magnum located by following the image of the slope of the inferior border of the basilar part of the occipital bone to its posterior limit.


S-sella–The point representing the geometric centrer of the pituitary fossa (sella turcica).






Figures 20.12A and B: Jarabak cephalometric analysis

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Po-porion (anatomic)–The superior point of the externalauditory meatus (superior margin of temporomandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).

Riedel Cephalometric Analysis (Figs 20.13A and B)Cephalometric landmarks used in Riedel cephalometric analysis are as given below:












Ul-maxillary central incisor (horizontal)–The most labial point on the crown of the maxillary central incisor.

Ul-maxillary central incisor (vertical)–The incisal edge of the maxillary central incisor.

L1-mandibular central incisor (horizontal)–The most labial point on the crown of the mandibular central incisor.

L1-mandibular central incisor (vertical)–The incisal edge of the mandibular central incisor.



Figures 20.13A and B: Riedel cephalometric analysis

A B


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Iip–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

APOcc-Anterior point of occlusion for the occlusal plane–A constructed point, the midpoint of the incisor overbite in occlusion

PPOcc-Posterior point of occlusion for the occlusal plane–The most distal point of contact between the most posterior molars in occlusion (Rakosi).

Maxillary central incisor is the most labial point on the crown of the maxillary central incisor.

Mandibular central incisor is the most labial point on the crown of the mandibular central incisor.

Schwartz Cephalometric Analysis (Figs 20.14A and B)Cephalometric landmarks used in Schwartz cephalometric analysis are as given below:







ii-incision inferius–The incisal point of the most prominent medial mandibular incisor


Wylie Cephalometric Analysis (Figs 20.15A and B)

Cephalometric landmarks used in Wylie cephalometric analysis are as given below:

sp–Dorsum of sella is the most posterior point on the internal contour of the sella turcica or hypophyseal fossa or pituitary fossa.

si–Floor of sella is the lower most point on the inner contour of the sella turcica or hypophyseal fossa or pituitary fossa.

Cl–Clinoidale is the most superior point on the contour of the anterior clinoid.

S–Sella is the midpoint of sella turcica or hypophyseal fossa or pituitary fossa.

Figures 20.14A and B: Schwartz cephalometric analysis

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ANS–Anterior nasal spine is the tip of bony anterior nasal spine in the midline or median plane.

A–Point A is the deepest point on the curved bony outline between the anterior nasal spine (ANS) and prosthion (Pr).

PNS–Posterior nasal spine is the intersection of continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose.

Ptm–Pterygomaxillary fissure is a bilateral tear drop shaped area of radiolucency, the anterior shadow of which represents the posterior surface of the tuberosity of the maxilla; the landmark is taken where the two edges, front and back appears to merge inferiorly.

Orbitale–The deepest point on the infraorbital margin.The midpoint, or is used where double projection gives rise to two points, or 1 and/or 2.





Steiner’s Cephalometric Analysis (Figs 20.16A and B)

Cephalometric landmarks used in Steiner’s cephalometric analysis are as given below:


The center of sella turcica–Located by inspection of the profile image of the fossa.






PNS–Posterior nasal spine is the intersection of a continuation of the anterior wall of the pterygopalatine fossa and the floor of the nose.


Figures 20.15A and B: Wylie cephalometric analysis

A B


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is - incision superius–The incisal point of the most prominent medial maxillary incisor.


APOcc-Anterior point of occlusion for the occlusal plane–A constructed point, the midpoint of the incisor overbite in occlusion

PPOcc-Posterior point of occlusion for the occlusal plane–The most distal point of contact between the most posterior molars in occlusion (Rakosi).

isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.


Pn–The most anterior point on the midsagittal profile of the nose. In cases where the tip of the nose was more than a definite point, pronasale was determined by drawing a line parallel to the line nasion to pogonion tangent to the most anterior point on the midsagittal profile of the nose.

Tweed’s Cephalometric Analysis (Figs 20.17A and B)

Cephalometric landmarks used in Tweed’s cephalometric analysis are as given below:






isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

Figures 20.16A and B: Steiner’s cephalometric analysis

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Wit’s Cephalometric Analysis (Figs 20.18A and B)

Wit’s AppraisalThe WIT’S (University of Witwatersrand, South Africa) appraisal.

WIT’S appraisal–WIT’S appraisal measures the extent to which the jaws are related to each other anteroposteriorly.

Cephalometric landmarks used in Wit’s cephalometric analysis are as given below:


Point B-supramentale–The deepest midline point on the mandible between infradentale and pogonion. The method of assessing the extent of jaw disharmony entails drawing perpendicular on a lateral cephalometric head film tracing from point A and B on the maxilla and mandible respectively, into the occlusal plane which is drawn through the region of maximum cuspal interdigitation: The point of contact on the occlusal plane from A and B are labeled AO and BO respectively.

Figures 20.18A and B: Wit’s appraisal

A B

Figures 20.17A and B: Tweed’s cephalometric analysis

A B


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Basis Cephalometric Analysis (Fig. 20.19)Cephalometric landmarks used in Basis cephalometric Analysis are as given below:


s-the center of sella turcica (the midpoint of the horizontal diameter).





Gn-gnathion–The deepest point on the chin.


Pog-pogonion–The most prominent point on the chin.


Isi–Incision superius incisalis is the incisal edge of the maxillary central incisor.

Isa–Incision superius apicalis is the root apex of the most anterior maxillary central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

Iii–Incision inferius incisalis is the incisal edge of the most prominent mandibular central incisor.

Iia–Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.

Cagliari Cephalometric Analysis (Fig. 20.20)Cephalometric landmarks used in basis cephalometric analysis are as given below:


s–The center of sella turcica (the midpoint of the horizontal diameter).





Figure 20.19: Basis cephalometric analysis Figure 20.20: Cagliari cephalometric analysis

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APOcc-Anterior point of occlusion for the occlusal plane– a constructed point, the midpoint of the incisor overbite in occlusion.

PPOcc-Posterior point of occlusion for the occlusal plane– the most distal point of contact between the most posterior molars in occlusion (Rakosi).




Articulare–Articulare is the point of intersection the dorsal contours of the processus articularis mandibulare and os temporale. The midpoint, a is used where double projection gives rise to two points, a1 and a2.

Chieti Cephalometric Analysis (Fig. 20.21)Cephalometric landmarks used in basis cephalometric analysis are as given below:


s–the center of sella turcica (the midpoint of the horizontal diameter).




Point Bsupramentale–The deepest midline point on the mandible between infradentale and pogonion.









Figure 20.21: Chieti cephalometric analysis


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APOcc-Anterior point of occlusion for the occlusal plane– a constructed point, the midpoint of the incisor overbite in occlusion.



Po-porion (anatomic)–The superior point of the external auditory meatus (superior margin of temporo mandibular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).


Articulare–Articulare is the point of intersection the dorsal contours of the processus articularis mandibulare and os temporale. The midpoint, a is used where double projection gives rise to two point, a1 and a2.

McGann Cephalometric Analysis (Fig. 20.22)Cephalometric landmarks used in basis cephalometric analysis are as given below:


s-the center of sella turcica (the midpoint of the horizontal diameter).












Iia—Incision inferius apicalis is the root apex of the most anterior mandibular central incisor; if this point is needed only for defining the long axis of the tooth, the midpoint on the bisection of the apical root width can be used.


APOcc-Anterior point of occlusion for the occlusal plane– a constructed point, the midpoint of the incisor overbite in occlusion



Po-porion (anatomic)–The superior point of the externalauditory meatus (superior margin of temporomandi bular fossa, which lies at the same level, may be substituted in the construction of Frankfort horizontal).


Articulare–Articulare is the point of intersection the dorsal contours of the processus articularis mandibulare and os temporale.The midpoint, a is used where double projection gives rise to two points, a1 and a2.

Figure 20.22: McGann cephalometric analysis

Index

Page numbers followed by f refer to figure

aAlar crease junction 128, 131 on graphic illustration 132f on lateral cephalogram 132fAngle of convexity 197Angulare point 184, 184fAntegonial tubercles 175, 176fAntegonion 176fAnterior nasal spine 10, 59, 123, 155f, 174, 194, 196,

200, 202, 204, 208, 209 on graphic illustration 60f on lateral cephalogram 60f pharyngeal wall 123 point of occlusion 10, 76, 77f, 208, 209 for occlusal plane 203, 205Applications of cephalometric landmarks 191, 193, Articulare 93, 95f, 174, 175f, 193Articulation of ethmoid bone 21 frontal bone 15, 26 temporal bone 31

bBasion 154f, 179f on graphic illustration 47f on lateral cephalogram 47fBasis cephalometric analysis 207, 207fBjork cephalometric analysis 193, 193fBolton’s point 10, 48, 196 on graphic illustration 50f on lateral cephalogram 49f

cCagliari cephalometric analysis 207, 207fCenter of sella turcica 196, 204, 208, 209Cephalometric analysis 3 X-ray tracing techniques 4Cephalostat 4Cervical bones 10, 99 point 198 vertebra 103, 104f, 118 vertebral maturation 119fCheilion 151Chieti cephalometric analysis 208, 208fClinoidale 38 on graphic illustration 38f on lateral cephalogram 38fCoben craniofacial and dentition analysis 194f cephalometric analysis 194Columella point 198

Condylion 95, 97f, 149, 150f anterioris 189, 189f lateralis 188, 189f medialis 188, 188f posterioris 190, 190fCoronal suture 160Cranial bones 10, 13Crista galli 160, 161fCuspid 169 bow 11, 135, 135f

dDeciduous dentition stage 70Dentition 71Di Paolo’s quadrilateral cephalometric analysis

200, 200fDorsum of sella 10, 36 on graphic illustration 36f on lateral cephalogram 36fDowns cephalometric analysis 195, 195f

eEruption chronology of primary teeth 70Ethmoid bone 10, 15, 21, 21f, 22f, 26Ethmoidale 24, 25f on lateral cephalogram 25f on graphic illustration 25fExocanthion 151, 152

fFacial bone and dentition 10, 57Farkas and coworkers soft tissue cephalometric

analysis 196, 196fFirst molar point 187, 187fFissure 123Floor of nose 160 sella 10, 37 on graphic illustration 37f on lateral cephalogram 37fForamina spinosa points 180, 180f spinosum 180, 181fFrontal bone 10, 26, 15, 15f on lateral cephalogram 15f cephalogram 3, 3fFrontomaxillary nasal suture 10 on graphic illustration 28f on lateral cephalogram 28f suture on graphic illustration 19f lateral cephalogram 19fFrontozygomatic suture 10

gGlabella 198Gnathion 89, 90f, 193, 196, 197, 201, 202, 204Gonion 93, 94f, 150, 150f, 202 point 187, 187f

hHarvold cephalometric analysis 196, 197fHassel and Farman developed method of skeletal

maturation 119fHasund cephalometric analysis 200, 200fHoldaway cephalometric analysis 197, 197fHyoid 101, 102f bone 101, 101f

iIncision inferius 194, 201, 202, 203, 204, 205 apicalis 10, 75, 76f, 170, 170f frontale 171, 171f incisalis 10, 74, 74f, 169, 170f superius 194, 201, 202, 203, 205 apicalis 10, 73, 73f, 166, 167f incisalis 10, 71, 72f, 165, 166fInfradentale 86, 194

jJarabak cephalometric analysis 201, 201fJugal process 164, 164f

lLabrale inferius 11, 136, 146, 147f, 198 on graphic illustration 137f on lateral cephalogram 137f superius 11, 134, 146, 146f, 198 on graphic illustration 134f on lateral cephalogram 134fLacrimal bone 15Laryngopharynx 123Lateral cephalogram 3, 3fLegan and Burstone soft tissue cephalometric

analysis 198, 198fLower face height 197 lip 11 pharynx 124

mMagnified image of anterior nasal spine on

graphic 60fMalare 175f

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n Ce

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Mandibular apical base midline 186, 186f central incisor 10, 80, 81f, 195, 202, 203 dental midline 185, 186f first molar 10, 81, 82f, 171, 171f, 195 length 197 molar 173, 173fMastiodale on lateral cephalogram 34fMastoid processes 160Maxilla 26, 59Maxillary apical base midline 185, 185f bone 15, 59f central incisor 10, 79, 79f, 195, 202, 203 first molar 10, 79, 80f, 168, 168f, 195 molar 167, 168fMcGann cephalometric analysis 209, 209fMedio-orbitale on lateral cephalogram 23fMentolabial sulcus 198Menton 92, 92f, 173, 174fMiddle cranial fossa points 182, 183fMixed dentition stage 70

nNasal bone 10, 15, 26, 26f, 26f crown 128, 129 on graphic illustration 129f on lateral cephalogram 129f, 129f process 15Nasion 16, 26, 194-196, 197, 200 on graphic illustration 16f, 27f on lateral cephalogram 16f, 27fNasopharynx 123Neck of crista galli 10, 23 on frontal cephalogram 23fNerve supply to mandible 85

oOccipital bone 10, 46, 46f condyles 160Occlusomandibular angle 199Occlusopalatal angle 199Odontoid 181, 181fOpisthion 48, 179, 180f on graphic illustration 49f on lateral cephalogram 48fOrbital plates 15Orbitale 52, 67, 148, 148f, 194-196 on graphic illustration 53f, 68f on lateral cephalogram 53f, 68fOropharynx 123

pPalatocranial angle 199Palatomandibular angle 199Parital bone 15Parts of ethmoid bone 21 frontal bone 15 hyoid bone 101 mandible 85Permanent dentition stage 71Pharynx 123

Philtrum 135fPlaned incisor position 136Planum sphenoidale 160Pogonion 88, 196, 197, 200, 201, 204Point A on graphic illustration 61f lateral cephalogram 61f on oral side of soft palate 123, 124 on pharyngeal side of soft palate 123, 124 T on graphic illustration 131 lateral cephalogram 131fPorion 32, 194-196 on lateral cephalogram 33fPosterior cranial vault points 183, 184f nasal spine 10, 64, 123, 208, 209 on graphic illustration 64f on lateral cephalogram 64f pharyngeal wall 123, 124 point of occlusion 10, 77, 78f, 208, 209 Vomer point 182, 183fPrognathion 197Pronasale 129, 144, 144f on graphic illustration 130f on lateral cephalogram 130fProsthion 62, 194 on graphic illustration 63f on lateral cephalogram 63fPterygoid point 10, 40 on graphic illustration 40f on lateral cephalogram 40fPterygomaxillary fissure 10, 44, 65, 123, 182,

182f, 195, 200 on graphic illustration 45, 66f on lateral cephalogram 45f, 66f

rRhinion 29 on graphic illustration 29f on lateral cephalogram 29fRickett’s cephalometric analysis 198, 199fRiedel cephalometric analysis 202Roof of orbit on graphic illustration 19f lateral cephalogram 19f orbital cavity 17

sSassouni cephalometric analysis 199, 199fSchwartz cephalometric analysis 203, 203fSella 10, 41, 152, 195 entrance 41, 153, 153f on graphic illustration 43f on lateral cephalogram 43f on graphic illustration 42f on lateral cephalogram 42fShapes of cervical vertebral bodies 119fSoft tissue cephalometric landmarks 11, 125, 127, 128,

133, 138 glabella 127 on graphic illustration 127f on lateral cephalogram 129f

gnathion 11, 139, 148, 148f, 198 on graphic illustration 139 on lateral cephalogram 139f menton 11, 198 nasal crown on graphic illustration 129f nasion 128, 143, 143f on graphic illustration 128f on lateral cephalogram 128f pogonion 11, 138, 147, 198 on graphic illustration 138f on lateral cephalogram 138f point B 147f on graphic illustration 137f on lateral cephalogram 137f submentale 136, 147 subspinale 11, 133, 145, 145fSphenoethmoidal point 10, 24, 42 on graphic illustration 44f on lateral cephalogram 43fSphenoethmoidale 24f on graphic illustration 24f on lateral cephalogram 24fSphenoid bone 10, 15, 35, 35fSpheno-occipital synchondrosis 10, 39, 50 on graphic illustration 39f, 51f on lateral cephalogram 39f, 50fSpina nasalis posterior 194, 200-202Spinal point 194Squamous part 15Steiner’s cephalometric analysis 204, 205fStomion inferius 11, 198 on graphic illustration 136f on lateral cephalogram 136f superius 11, 198Subnasale 131, 144, 198 on graphic illustration 132f on lateral cephalogram 132fSubspinale 194 on graphic illustration 133f on lateral cephalogram 133fSuperior pharyngeal wall 123, 124 surface of floor of pituitary fossa 160Supra-orbitale 17 on graphic illustration 18f on lateral cephalogram 18f

tTemporal bone 10, 15, 31, 31fTemporale on graphic illustration 22f, 54f lateral cephalogram 22, 54fTemporomandibular joint 196Tip of uvula 123, 124Top of nasal septum 161, 161fTracing basion on lateral cephalogram 47 Bolton’s point on lateral cephalogram 50 neck of crista galli on lateral cephalogram 23 of anterior nasal spine on lateral cephalogram 60, 155 point of occlusion on lateral cephalogram

76 of articulare on lateral cephalogram 94, 174

Index213

of gnathion on lateral cephalogram 90 of hyoid on lateral cephalogram 102 of incision inferius apicalis on lateral cephalogram 75, 171 incisalis on lateral cephalogram 75 of incision superius apicalis on lateral cephalogram 74, 167 incisalis on lateral cephalogram 72, 166 of infradentale on lateral cephalogram 87 of mandibular central incisor on lateral cephalogram 81 first molar on lateral cephalogram 81, 172 of mastiodale on lateral cephalogram 34 of maxillary central incisor on lateral cephalogram 79 first molar on lateral cephalogram 80, 168 of menton on lateral cephalogram 92, 93, 95,

174 of MI on lateral cephalogram 82, 172 of MS on lateral cephalogram 83 of nasion on lateral cephalogram 17 of orbitale on lateral cephalogram 54

of pogonion on lateral cephalogram 88 of point B on lateral cephalogram 88 of posterior nasal spine on lateral cephalogram 65 point of occlusion on lateral cephalogram

78 of sella on lateral cephalogram 41, 152 opisthion on lateral cephalogram 48 pterygoid point on lateral cephalogram 41 rhinion on lateral cephalogram 30 roof of orbit on lateral cephalogram 18 spheno-occipital synchondrosis on lateral

cephalogram 40, 51 supra-orbitale on lateral cephalogram 17Trichion 196Tweed’s cephalometric analysis 205, 206fTypes of cephalogram 3

uUpper and lower lips 11 lip 11

pharynx 124 point of tongue 123, 124Uses of cephalometric analysis 3

vVermillion 135, 135f border of upper lips 11Vertex 143, 143f

wWit’s cephalometric analysis 206Wylie cephalometric analysis 203, 204f

zZygion 149, 149f, 163, 163fZygoma 162, 162fZygomatic arch 10, 32, 163, 163f bone 10, 15, 52, 52f process 15 prominence 149, 149f suture point 164, 164f

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An Atlas on Cephalometric Landmarks

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