Orthognathic Surgery Indication — ORE Part 1 MCQ

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ModerateOrthodonticsOrthognathic Surgery IndicationORE Part 1

A 16-year-old has a severe Class II division 1 malocclusion, a 14 mm overjet and marked mandibular retrusion. Skeletal assessment indicates that the pubertal growth spurt has finished. Which is the most appropriate definitive treatment plan?

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Correct answer: C — Fixed-appliance orthodontics with mandibular advancement surgery

Explanation lettering: E = shown as A · A = shown as C · C = shown as E

A is correct. This is a severe skeletal Class II discrepancy: the overjet is 14 mm, there is marked mandibular retrusion, and the pubertal growth spurt has finished. Evidence indicates that, beyond the growth spurt, Class II patients with overjet greater than 10 mm and substantial mandibular deficiency are likely to require orthognathic correction rather than orthodontics alone. Treatment is normally coordinated as presurgical fixed-appliance orthodontics followed by mandibular advancement surgery. A Twin Block is most effective during active pubertal growth, so B is inappropriate as definitive management. Headgear does not address the primary mandibular deficiency and is growth dependent. Premolar extraction camouflage may reduce overjet dentally but does not correct this severe skeletal discrepancy. Further observation will not provide the mandibular growth needed for correction.

Reference: Proffit WR, Phillips C, Tulloch JF, Medland PH. Surgical versus orthodontic correction of skeletal Class II malocclusion in adolescents: effects and indications. International Journal of Adult Orthodontics and Orthognathic Surgery. 1992;7(4):209–220. https://pubmed.ncbi.nlm.nih.gov/1298780/