Which value describes the SNB angle in mandibular prognathism?

Which value describes the SNB angle in mandibular prognathism?

• A. Less than norm
• B. 80º
• C. More than norm
• D. 78º

Answer: (C)

SNB angle shows how far forward the mandible sits relative to the cranial base. When the mandible is prognathic, it projects forward, increasing the SNB angle beyond the normal range. The normal SNB is about 80 degrees (roughly 78–82°, depending on population). So a prognathic mandible would have an SNB value greater than this normal range. Values around 80° are near average, while 78° is below average. Therefore, the description that fits mandibular prognathism is more than normal.

SNB angle shows how far forward the mandible sits relative to the cranial base. When the mandible is prognathic, it projects forward, increasing the SNB angle beyond the normal range. The normal SNB is about 80 degrees (roughly 78–82°, depending on population). So a prognathic mandible would have an SNB value greater than this normal range. Values around 80° are near average, while 78° is below average. Therefore, the description that fits mandibular prognathism is more than normal.