Date post: | 22-Nov-2014 |
Category: |
Documents |
Upload: | selimir-prodanovic |
View: | 129 times |
Download: | 8 times |
Basic Cephalometrics
Mark H. Taylor, D.D.S., F.A.C.D.
Cephalometrics is a technique employing oriented radiographs for the purpose of making head measurements.
Purpose of Cephalometrics
• Study craniofacial growth• Diagnosis• Planning orthodontic treatment• Evaluation of treated cases
15"60"
Source Plane
X-ray Source
Patient in Head Positioning Device
Mid-saggital Plane
Film Plane
X-ray Film in Cassette
Cephalostat
Cephalostat
Cephalostat
White Black Israeli Chinese Japanese
SNA 82 85 82 82 81
SNB 80 81 78 79 77
ANB 2 4 4 3 4
U1-NA 4 mm, 22 7 mm, 23 5 mm, 24 5 mm, 24 6 mm, 24
L1-NB 4 mm, 25 10 mm, 34 6 mm, 29 6 mm, 27 8 mm, 31
U1-L1 131 119 124 126 120
GoGn-SN 32 32 35 32 34
L1-MnPl 93 100 93 93 96
L1-FH 62 51 57 57 57
Y axis 61 63 61 61 62
from Proffit,Contemporary Orthodontics, 1992
Cephalometric Values for Selected Groups
What Are We Trying to Accomplish?
• Find out skeletal classification– anteroposterior– vertical
• Find out angulation of incisors• Consider soft tissue
– facial profile– airway considerations
What Are We Trying to Accomplish? (In other words)
• Is the patient Class I, II, III skeletal?• Does the patient have a skeletal open bite
growth pattern, or a deep bite growth pattern, or a normal growth pattern?
• Are the maxillary/mandibular incisors proclined, retroclined or normal?
• Is the facial profile protrusive, retrusive, or straight; can the patient breathe normally?
Structures to be Traced
Sella
Porion
Gonion PNS
Menton
Gnathion
Pogonion
B PointA PointANS
Orbitale
Nasion
Articulare
Standard Cephalometric Landmarks
Radiographic Landmarks
SN Plane
Frankfort PlanePalatal Plane
Occlusal Plane
Mandibular Plane
Frequently Used Planes
8822
Antero-posterior maxillary assessment
Skeletal AssessmentSNA
8800
Antero-posterior mandibular assessment
Skeletal AssessmentSNB
22Antero-posterior bimaxillary assessment
Skeletal AssessmentANB
-1 mm-1 mmBO anterior BO anterior to AOto AO
Skeletal AssessmentWits (AO-BO)
6666
Skeletal AssessmentY Axis
5959
Vertical Skeletal Assessment
Skeletal AssessmentY Axis (to Frankfort Horizontal)
3232
Vertical Skeletal Assessment
Skeletal AssessmentNS(SN plane)-GoGn
101044
Incisor Angulation Assessment
Dental AssessmentU1-NS (Max 1 - SN)
2222
Dental AssessmentMax 1 - NA (degrees)
4 4 mmmm
Dental AssessmentMax 1 - NA (mm)
9955
Incisor Angulation Assessment
Dental AssessmentL1-GoGn (Man 1 - GoGn)
2255
Dental AssessmentMan 1 - NB (degrees)
4 4 mmmm
Dental AssessmentMan 1 - NB (mm)
2 mm 2 mm +/- 2+/- 2
Dental AssessmentAPog - Man 1
131300
Inter-Incisor Angulation Assessment
Dental AssessmentU1-L1 (Max 1 - Man 1)
-2 -2 mmmm
CHANGES WITH AGE!
Soft Tissue AssessmentE Plane
>4 >4 mm.mm.
Soft Tissue Assessment
Composite Cephalometric Tracing
Children with airway obstruction, whencompared to normal controls, show:
Nasorespiratory Considerations
• Increased total and lower face heights• More retrognathic mandibles• Steeper (increased) mandibular plane
angles• Spontaneous improvement after
reestablishment of normal respiration
Cases