Which is the FMA angle change for hyperdivergent facial growth?

Which is the FMA angle change for hyperdivergent facial growth?

• A. increases
• B. decreases
• C. remains constant
• D. does not change

Answer: (A)

The angle between the Frankfort horizontal plane and the mandibular plane (FMA) rises with hyperdivergent facial growth because this pattern involves greater vertical facial height and a clockwise rotation of the mandible. As the mandible tips downward and backward relative to the cranial base, the mandibular plane becomes more inclined, increasing the angle it makes with Frankfort horizontal. That vertical growth pattern therefore elevates the FMA. In contrast, hypodivergent growth tends to flatten the mandibular plane and decrease the FMA, or keep it relatively stable, so the observed change here is an increase.

The angle between the Frankfort horizontal plane and the mandibular plane (FMA) rises with hyperdivergent facial growth because this pattern involves greater vertical facial height and a clockwise rotation of the mandible. As the mandible tips downward and backward relative to the cranial base, the mandibular plane becomes more inclined, increasing the angle it makes with Frankfort horizontal. That vertical growth pattern therefore elevates the FMA. In contrast, hypodivergent growth tends to flatten the mandibular plane and decrease the FMA, or keep it relatively stable, so the observed change here is an increase.