Facial flatness indices: application in orthodontics

Facial flatness indices have been used in anthropology to discern differences among populations. They were evaluated on skulls from around the world. AIMS: (1) to evaluate the use of facial flatness indices in orthodontics and (2) to assess their variation among malocclusions, age and sex. MATERIALS AND METHODS: A total of 322 cone beam computed tomography radiographs were digitized and three facial indices (frontal, simotic and zygomaxillary) along with three transverse distances (fmo1–fmo2, zma1–zma2 and n1–n2) were assessed and compared between different groups. RESULTS: The zygomaxillary index was increased in Class II (32.6 ± 0.42; p < 0.001) and decreased in Class III malocclusions (29.4 ± 0.66; p < 0.001) compared to Class I (31.18 ± 0.3; p < 0.001). The frontal and nasal flatness are not characteristic features of any of the sagittal malocclusions. Facial flatness indices did not differ between males and females and between growing and non-growing patients. CONCLUSION: The position of subspinale point (A point) forward or backward relative to the zygomaxillary width is a factor of assessment of facial flatness. The zygomaxillary index could be helpful in weighting proportionally the width of the maxilla (expansion) relative to its sagittal position in Class II and Class III malocclusions.