What does an SNA angle greater than 80 indicate about the mandible?

An SNA angle greater than 80 degrees indicates that the maxilla is positioned forward relative to the cranial base, suggesting that the mandible may be positioned more towards the back, contributing to a prognathic classification. A higher SNA angle often reflects an imbalance where the maxilla is positioned more anteriorly compared to the mandible, which can lead to an excess in the projection of the maxilla relative to the mandible, classifying the mandible in a prognathic position. This information is crucial in orthodontics and dentofacial assessments as it helps in diagnosing skeletal relationships and planning treatment accordingly, especially in patients presenting with occlusal and alignment issues.

In contrast, a lower SNA angle would typically suggest either a retrognathic mandible or a normal relationship, while an SNA angle around 80 degrees is more representative of skeletal normalcy or a Class I relationship, where both the maxilla and mandible are more harmoniously aligned. Thus, the higher value firmly supports the notion of a prognathic mandible.