Abstract
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 MethodsA 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.ResultsThe 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.ConclusionThe 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.
Highlights
The purpose of this study was to evaluate the use of facial flatness indices in orthodontics and assess the association between facial flatness indices and age, sex and sagittal malocclusions, measured through three-dimensional radiographic technology
In 1973, Yamaguchi described three facial indices evaluating flatness at different levels of the face, which have been used only on dry skulls in anthropological studies. This is the first study where the flatness measurements are extrapolated and applied on 3D radiographs (CBCTs) to try to induce new interpretations of flatness related to age and sex in orthodontics
Facial flatness indices evaluation is important in orthodontics to appraise the harmonization within the different proportions of the face
Summary
Facial flatness has often been considered in the assessment and evaluation of disparity among populations (Debets, 1951; Oschinsky, 1962; Alekseev, 1979; Yamaguchi, 1973, 1980; Bulbeck, 1981; Rak, 1986; Trinkaus, 1987; Gill et al, 1988; Pope, 1991, 1992; Ishida, 1992).Various measurements have been used to evaluate frontal and facial flatnesses in different populations to compare modern to ancient human beings (Hanihara, 2000). Woo & Morant (1934) evaluated facial flatness on dry skulls and subsequently, many anthropologists have used their method with minor modifications. Yamaguchi (1973) proposed three sets of facial flatness measurements: the frontal index, the simotic index (described by Woo & Morant (1934)) and the zygomaxillary index (described by Alekseev & Debets (1964)). Facial flatness has often been considered in the assessment and evaluation of disparity among populations (Debets, 1951; Oschinsky, 1962; Alekseev, 1979; Yamaguchi, 1973, 1980; Bulbeck, 1981; Rak, 1986; Trinkaus, 1987; Gill et al, 1988; Pope, 1991, 1992; Ishida, 1992). Yamaguchi (1973) proposed three sets of facial flatness measurements: the frontal index, the simotic index (described by Woo & Morant (1934)) and the zygomaxillary index (described by Alekseev & Debets (1964)). These indices have been mostly used in anthropological studies.
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