Class 11

ByDr.Noreen

Mohammed

According to British Standards classification: “The lower incisor edges lie posterior to the cingulum plateau of the upper incisors, there is an increase in overjet and the upper central incisors are usually proclined.”

CLASS II DIVISION 1

etiology

Skeletal pattern

Soft tissue

habits

Dental factors

SKELETAL PATTERN• Usually associated with

skeletal Class II pattern, due to retrognathic mandible.

• Proclination of the upper

incisors &/or retroclination of the lower incisors by a habit or the soft tissues can result in an increase in overjet on skeletal Class I or even a Class III pattern

Influence of soft tissue is mainly mediated by skeletal pattern, antero-posteriorly & vertically.

Patient’s lips are incompetent, try to achieve anterior oral seal in one of the following ways:

Circumoral muscular activity. Forward postured mandible Lower lip is drawn up behind the upper incisors. Tongue is placed forward between incisors to

contact lower lip. Combination of these.

SOFT TISSUES

HABITS DIGIT SUCKING: – Proclination of the upper

incisors. Retroclination of the lower

labial segment. Incomplete overbite or

localized anterior open bite. Narrowing of maxillary

arch, Due to alteration in the balance between cheek & tongue pressure.

Crowding in upper incisors out of the arch labially result in exacerbation of the overjet

DENTAL FACTORS

Increased overjet. Often increased overbite. Incompetent lips. Class II molar, canine & incisor relationship.

OCCLUSAL FEATURESAnterior open

bite

Angle’s Class II div 2 malocclusion is characterized by Class II Molar relation.

It is when the buccal groove of the first mandibular molar occludes distal to the mesiobuccal cusp of the first maxillary molar, with retroclination of the maxillary central incisors

Incidence : 5 – 10 %

Class II Div 2

The lower incisor edges occlude posterior to the cingulum plateau of the upper incisors and the lower centrals are retroclined

British standards classification of incisor relationships

Van der Linden classification of Class II Div 2 depending on the spatial conditions in the maxillary dental arch :

Type A The upper central and lateral incisors are retroclined. It is of less severe in nature.

Type B-: The central incisors are retroclined and overlapped by the lateral incisors

Type C-: The central and lateral incisors are retroclined and overlapped by the canines.

1) squarish face (Brachycephalic).

2) Upper lip is invariably short and positioned high with respect to the upper anteriors.

3) Lower lip is thick flabby covering the upper incisors and exhibiting

4) Usually straight to mildly convex profile because of less skeletal discrepancy and the retroclined incisors

5) Deep mentolabial sulcus

CLINICAL FEATURES OF CLASS II DIV 2 EXTRAORAL

1) Class II molar relation indicating distal relation of mandible to the maxilla.

2) Decreased overjet, an increased overbite.3) Deep bite usually traumatic

INTRAORAL CHARACTERISTICS

1) The upper arch is usually broad, ‘U’ shaped.

2) The palatal vault is usually deep.

3) An exaggerated curve of spee

Diagnosis is the process of attempting to determine or identify a possible disease or disorder

(Extra oral and Intra oral features)

CLINICAL EVALUATION

Case history , Photographic analysis , Radiographic analysis , Cast analysis ,

DIAGNOSTIC AIDS

Examination of the tempromandibular joint Examination of orofacial dysfunction

FUNCTIONAL ANALYSIS

Extra-oral Photographic

analysis

Class II divison 1 profile: convex Shape of head : dolicocephalicMento labial sulcus : shallow/deep

Class II divison 2

Profile : straight / convexShape of head : mesocephalic /dolichocephalicMento labial sulcus : normal

Clinical features of class II -division 1

classII molar relation, that may vary from end on molar to fully fledged class II

o proclined maxillary anteriors with resultant increased overjet

o spaced dentition

Intra oral photographic

analysis

V – shaped palatal arch

Excessive curve of spee

Deep palate

Increased over jet

Class II divison 2 malocclusion Excessive lingual

inclination ofthe maxillary central incisors overlapped on the labial by the maxillary lateral incisors.

In some Cases , both the central and the

lateral incisors are lingualy inclined and the canines overlap the lateral incisors on the labial.

o U – shaped palatal arch

o A deep overbite and minimal over jet

o with extreme overbite, the incisal edges of the lower incisors may contact the soft tissues of the palate

o In the absence of over jet) mandibular labial gingiva get traumatised by lingually inclined maxillary incisors

Intra-oral photographic

analysis

Lateral cephalometrics analysis

CEPHALOMETRIC ANALYSIS

Analysis of facial skeleton Analysis of mandibular and maxillary base Dento alveolar analysis

(N-S-Ar) .

provides an assessment of the relationship between anterior and posteriolateral cranial bases

Mean value 123+/-5

Thus a large saddle angle usually signifies a posterior condylar position and a mandible That is posteriorly positioned with respect to cranial base and maxilla

SADDLE ANGLE :

(S-Ar-Go)

Its size depend on position of the mandible ;

Angle is Large if mandible is retrognathic

Angle is Small if mandible is prognathic

Mean value(143+_6)

ARTICULAR ANGLE:

The angle S-N-A expresses the sagittal relationship between the anterior limit of the maxillary base and the anterior cranial base.

Mean value ( 81*)

It is large in prognathic maxillas

small in retruded maxillas .

S-N-A angle:

The angle S-N-B expresses the sagittal relationship between the anterior extent of the mandibular base and anterior cranial Base

Mean value (79*)

It is large with a prognathic mandible

It is small with a retrognathic mandible .

S-N-B angle:

Reference planes for lip profile assessment

Ricketts drawn from tip of nose to skin pogonion Normal relation means : upper lip is 2-3 mm Lower lip 1-2 mm behind this.

Ricketts lip analysis ( E

plane)

pog

Three treatment approaches are available : 1) Growth modification 2) Dental camouflage 3) Orthognathic surgery (with orthodontic treatment)

Treatment options for skeletal Class II malocclusions

1) Growth modification for class II skeletal problem: (Orthopedic treatment)

- The goal of growth modification is to enhance the unacceptable skeletal relationship by modifying remaining facial growth pattern of the jaws.

- Optimum timing : Pre-pubertal growth spurt (active growth period)

Two types of orthopedic appliances used in skeletal class II

A) Headgear ( extra-oral force)

B) Functional appliances ( Removable and fixed )

It delivers an extra-oral orthopedic force to compress the maxillary sutures and modify the pattern of bone apposition at these sites.

2 TYPES

Facebow J-Hooks

(maxillary excess ) (Maxillary anterior retraction)

and intrusion

A- Headgear:

(cervical)-Distal and extrusive forces on maxillary mollars . (occipital)-posterior and inferior extra-oral force -Distal and intrusive forces on the

maxillary molar - extra-oral force is directed

superior and posterior -Increases vertical dimension -A-P and Vertical maxillary excess

( decreases V.D) - used in A-P maxillary excess with flat mand,plane

B- Functional appliances:

Class II functional appliances are designed to position the mandible in a downward and forward to enhance its mandibular growth pattern.

Indication: Mandibular deficiency Removable Functional: Fixed

Functional: -Activator -Herbst - Bionator -Jasper jumper -Twin bloc - Frankyl II

2) Dental Camouflage: It is a treatment that seeks to create a dental compensation to hide the skeletal

discrepancy Maxillary Retroclination and Mandibular Protraction.Indicated: 1) Adults 2) Mild to Moderate skeletal Class II cases 3) Minimal dental crowding . 4) Acceptable facial esthetics 5) Usually requires extraction Dental camouflage without extraction is rare in case of skeletal class

II -Mild skeletal class II cases - Mild excessive overjet - Adequate space available - Max Molar distalization

3) Orthognathic surgery: A combination of orthodontic therapy and Orthognathic surgery for

the correction of moderate to severe skeletal class II malocclusion (Adults, no growth potential)

Indicated:

1) Moderate to Severe skeletal discrepancy 2) Facial imbalances or asymmetries: long lower face , Gummy smile 3) Limitations of tooth movement : Upright on basal bone 4) Relapse potential of orthodontic treatment. 5) Severe crowding and protrusion in the dental arches with skeletal class

II malocclusion (extraction space is not sufficient to correct buccal occlusion)

Surgical correction includes: 1) Mandibular Advancment: Indicated: skeletal class II cases with mandibular deficiency

The intraoral sagittal split ramus osteotomy is the most popular technique for surgical mandibular advancment.

2) Maxillary Impaction: ( Le Fort 1 maxillary osteotomy )

Indicated: Vertical Maxillary excess

Maxillary Impaction may include 1)Total maxillary osteotomy ( maxillary excess ant. and post.) 2) Bilateral posterior segmental maxillary osteotomy ( excess

localized posterior)

Vertical maxillary excess in the anterior and posterior region of

maxilla

Requires maxillary impaction by a total maxillary ostoetomy .

To correct the: 1) Gummy smile 2) excessive lower facial height 3) incompetent lips 4) mandible will rotate anti-clock

wise

- Anterior Maxillary sub-apical setback Indicated: Maxillary excess is in A-P

dimension/ Mid-face protrusion ( No vertical excess)

- Combined Surgical approaches : Indicated: Maxillary excess (vertical or

A-P) combined with mandibular deficiency.

Moderate class II malocclusions are usually associated with mandibular deficiency or maxillary excess Resulting in a compromised facial esthetics.

The choice between orthognathic surgery or orthodontics as a treatment option might be confusing to the orthodontist in borderline cases.