9 Increased overjet
Emma, aged 11, is teased at school about her prominent upper front teeth (Fig. 9.1). What are the possible causes and how may it be treated?
The upper front teeth have always been prominent, even when the primary incisors were present. Emma is teased about her teeth at school and the teasing is upsetting her. She recently fell in the school yard and hit her two upper front teeth on the ground. Fortunately there was only minimal incisal enamel damage to .
The skeletal pattern is the relationship of the mandibular to the maxillary dental base in all three planes of space – anteroposterior, vertical and lateral. With the patient seated upright with the Frankfort plane (superior aspect of the external auditory meatus to the inferior aspect of the orbital margin) horizontal, the lips in repose and the teeth in maximum interdigitation, assessment should be as follows:
Due to variation in lip thickness, this method is not always reliable and palpation of the alveolar bases over the apices of the upper and lower incisors in the midline has been claimed to give a better estimate of skeletal pattern.
The intraoral views are shown in Figures 9.1 and 9.3. What do these show?
There is a Class II division 1 incisor relationship with increased overjet (measured 7 mm clinically); the overbite is increased and complete. The buccal segment relationship is a half-unit Class II bilaterally. There is a lingual crossbite (scissors bite) affecting .
|Skeletal pattern||May be Class I, II or III|
|If Class II, mandibular deficiency is almost entirely the primary cause but may be excessive horizontal maxillary growth or a combination of the two factors|
|Soft tissues*||Lower lip lying under the upper incisors to create an anterior oral seal will procline the upper incisors and retrocline the lower incisors (likely if there is a Class II skeletal pattern, reduced lower facial height and lip incompetence)|
|Hyperactive lower lip will retrocline the lower incisors|
|Primary atypical swallowing pattern (endogenous tongue thrust) will tend to procline upper (but also lower) incisors|
|Digit sucking habit||If present for more than 6 hours out of 24, it will procline upper incisors, retrocline lower incisors, create an anterior open bite and a tendency to buccal segment crossbite|
|Overjet increase is often asymmetrical due to digit positioning|
|Crowding||Labial displacement of upper incisors and/or lingual displacement of lower incisors|
|Any combination of above|