Which cephalometric value assesses the sagittal relationship between the maxilla and mandible?

Which cephalometric value assesses the sagittal relationship between the maxilla and mandible?

• A. SNA angle
• B. ANB number (cephalometric analysis)
• C. SNB angle
• D. Interincisal angle

Answer: (B)

The key idea is how the two jaws relate to each other in the forward–backward (sagittal) dimension. The ANB angle does this by comparing where the maxilla and mandible sit relative to the cranial base, using nasion as the reference point. It’s formed at nasion by the lines to point A (maxilla) and point B (mandible). This single angle captures the sagittal discrepancy between the jaws: a larger than normal ANB suggests the maxilla is ahead of the mandible (class II skeletal relationship), a normal ANB around about 2 degrees indicates balanced AP positions, and a smaller or negative ANB indicates the mandible is ahead of the maxilla (class III). SNA and SNB tell you where each jaw sits relative to the cranial base separately, which is useful, but they don’t directly quantify the jaw–jaw relationship. Interincisal angle is about the inclination of the incisors, not the skeletal jaw relationship. Keep in mind that ANB can be influenced by nasion position or cranial base length, so in some cases adjunct measures (like a Wits appraisal) are helpful for a fuller picture.

The key idea is how the two jaws relate to each other in the forward–backward (sagittal) dimension. The ANB angle does this by comparing where the maxilla and mandible sit relative to the cranial base, using nasion as the reference point. It’s formed at nasion by the lines to point A (maxilla) and point B (mandible). This single angle captures the sagittal discrepancy between the jaws: a larger than normal ANB suggests the maxilla is ahead of the mandible (class II skeletal relationship), a normal ANB around about 2 degrees indicates balanced AP positions, and a smaller or negative ANB indicates the mandible is ahead of the maxilla (class III).

SNA and SNB tell you where each jaw sits relative to the cranial base separately, which is useful, but they don’t directly quantify the jaw–jaw relationship. Interincisal angle is about the inclination of the incisors, not the skeletal jaw relationship. Keep in mind that ANB can be influenced by nasion position or cranial base length, so in some cases adjunct measures (like a Wits appraisal) are helpful for a fuller picture.