A decreased ANB angle indicates which type of skeletal pattern?

A decreased ANB angle indicates a skeletal Class III pattern. The ANB angle is formed by three key points: A (the most anterior point on the maxilla), N (the nasion or the bridge of the nose), and B (the most anterior point on the mandible).

In orthodontics, the ANB angle is crucial in assessing the relationship between the maxilla and the mandible. A normal ANB angle is typically around 2 to 4 degrees, which corresponds to a Class I skeletal pattern. When the ANB angle is decreased (less than 2 degrees), it suggests that the mandible is positioned further forward relative to the maxilla, which is characteristic of a Class III skeletal relationship. This positioning can result in an anterior crossbite, where the lower teeth are positioned ahead of the upper teeth in occlusion.

Skeletal Class II would have an increased ANB angle, indicative of the maxilla being positioned forward relative to the mandible, whereas a normal ANB angle corresponds to Class I. Class IV is not typically recognized in the standard classification of skeletal relationships in orthodontics. Therefore, the interpretation of a decreased ANB angle clearly aligns with a Class III skeletal pattern.