Class 11: The lower incisor edges occlude posterior to the cingulum plateau of the upper incisor.
Division 2: upper central incisor are retroclined, overjet is usually minimal but may be increased.
Prevalence: 10% Caucasian.
Class 11 division 2 malocclusion
Commonly associated with a mild class 11 skeletal pattern.
Where the lower lip line is high relative to the upper incisors a class 11 division 2 can result.
Where the upper incisor lie outside the control of the upper lip a class 11 division 1 can result.
Reduced vertical dimension (face high)= absence of an occlusal stop to the lower incisor= increased overbite.
a relatively wide maxillary base may lead to buccal cross bite of premolars.
Mediated by skeletal pattern
Lower facial high reduced= lower lip line higher relative to the crown of the upper incisor= retrocline the upper incisor.
In some cases, the upper lateral incisor may escape the action of the lower lip (shorter crown length).
Active muscular lips (bimaxillary retroclination).
lack space of the upper lateral incisor = crowded and rotated mesiolabially out of the arch .
Retroclination of the lower labial segment (increased overbite).
poorly developed cingulum on the upper incisors.
Acute crown/root angulations.
Typically 1 1 retroclined; 2 2 proclined mesiolabial rotated.
Occasionally 21 12 and 21 12 retroclined with
3 3 buccal.
Overbite may be traumatic.
Mild class 11 buccal segment relationchip with possible buccal cross bite of 4 4 .
2 1 1 retroclined, 3 buccal, buccal crossbite 4
Treatment planning principles:
Beware of the lower arch extraction only, as a deep overbite may become traumatic as the lower labial segment drops lingually.
Some proclination of 21 12 and mild lower intercanine expansion is often possible and stable, thereby providing space for overbite reduction and the relief of crowding.
Class 1 or mild class 11 skeletal pattern
Where over bite and retroclination of 1 1 or 21 12 are to be accepted. Confine treatment to the relief of upper arch crowding and upper labial segment alignment.
If lower arch accepted, upper arch mildly crowded with at most half unit class molar relationship,
Consider moving the upper buccal segment distally with headgear (which may require the removal of 7 7 ), followed by the canine retraction just sufficient for labial segment alignment.
Extraction of 5 5 and fixed appliance therapy is an alternative where cooperation with headgear is unlikely. If buccal segment relationship is a full unit class 11 or extraction of 5 5 is required for the relief of crowding, removal of 4 4 is usually indicated.
Where overbite and retroclination of 1 1 or 21 12 to be corrected. Indicated where the overbite is deep and complete on gingival or palatal tissues with existing or potential trauma. Fixed appliance are required to effect overbite reduction by proclination of lower incisor alone or in combination with palatal/lingual torque. Extraction are required if lower arch crowding is severe; distal movement of buccal segment or extraction provide space for the correction of the incisor relationship in the upper arch. Reduce the interincisal angle to 135 degree for the best prospect of stable correction.
More marked class 11 skeletal discrepancy
Growth modification: This is indicated in growing child with ideally a well aligned lower arch.
Procline 1 1 or 21 12 and then use a functional appliance. To detail occlusion, may then require fixed appliance.
Orthognathic surgery: This is indicated in an adult patient particularly if an overbite is deep and traumatic.
Post treatment stability
Alignment of 2 2 and overbite reduction are prone to replace. Bonded retention is advisable for 2 2 .
Flat anterior bite plane on URA retainer is recommended until growth is complete to promote overbite stability.
Following extraction of 4 and fixed appliance therapy
After functional followed by fixed appliance therapy