Decreased SNA indicates which type of mandible?

A decreased SNA angle suggests that the maxilla is positioned further back relative to the cranial base. In this context, if the maxilla is retruded, the mandible's position becomes relatively advanced to maintain a harmonious occlusion, which results in a retrognathic appearance or classification of the mandible.

A retrognathic mandible indicates that the mandible is positioned more posteriorly in relation to the maxilla, often leading to an underbite or a prominent maxilla in facial profile analysis. This can have various implications for occlusion and aesthetics, making it crucial to accurately assess this relationship in cephalometric evaluations.

While an orthognathic mandible denotes proper alignment of the maxilla and mandible, and a prognathic mandible refers to a mandible that is positioned more forward than the maxilla, the context of a decreased SNA specifically highlights the retrognathic classification. Mesognathic refers to a more neutral or average relationship between the maxilla and mandible, which does not apply with the context of a decreased SNA.