Extracranial versus intracranial references in individual cephalometric analysis.

This study was undertaken to determine whether angles SNA and ANB genuinely represent both the degree of maxillary prognathism and the intermaxillary relationship in natural head position (NHP). Pearson's r correlation coefficients were used to assess the associations between these angles, and variables based on NHP and extracranial reference lines. A large sample (n = 106) was used, comprising subjects with a variety of facial patterns. This was also divided into subgroups comprising subjects with similar facial configurations, determined by natural head position parameters. For the subgroups, SNA and ANB were not associated with the variables based on NHP, and showed high variations in subjects with similar facial patterns. SNA also showed statistically significant and high correlation with the inclination of the NSL to the true vertical.