A patient with a HIGH mandibular plane angle is most likely to present with which of the following?

Correct answer: A. Anterior open bite

• A. CORRECT. A high mandibular plane angle defines the hyperdivergent, vertical growth pattern: posterior dentoalveolar height is excessive, the mandible rotates downward and backward, the lower facial third is long, and the anterior teeth fail to meet — an anterior open bite tendency.
• B. The molar relationship is an anteroposterior finding and does not follow from the mandibular plane angle.
• C. Deep overbite is the hallmark of the opposite pattern, the LOW-angle hypodivergent (brachyfacial) patient with a short lower face and strong musculature.
• D. Posterior crossbite reflects a transverse discrepancy — maxillary constriction — and is independent of the vertical dimension, though the two can coexist.

Note: High angle (dolichofacial): long face, open bite tendency, weak musculature, poor anchorage, unfavourable for extrusive mechanics. Low angle (brachyfacial): short face, deep bite, strong masseter, excellent anchorage, resistant to bite opening.