Alternative cone-beam computed tomography method for the analysis of bone density around impacted maxillary canines

Genetic and environmental etiologic factors have been described for maxillary canine impaction, except for the trabecular bone characteristics in the impacted area. The aim of this study was to evaluate the surface area and fractal dimension of the alveolar bone on cone-beam computed tomography (CBCT) images of patients with maxillary impacted canines.

The sample comprised preorthodontic treatment CBCT images of 49 participants with maxillary impacted canines (31 unilateral and 18 bilateral). CBCT images were acquired in portrait mode (17 × 23 cm high field of view) at 120 kV, 5 mA, 8.9-seconds exposure time, and 0.3-mm voxel size. Coronal slices (0.3 mm) were obtained from the right and left alveolar processes between the first and second maxillary premolars. We collected 64 × 64-pixel regions of interest between the premolars to assess maxillary bone area and fractal dimension using ImageJ software (National Institutes of Health, Bethesda, Md). Comparisons were made using paired t tests and linear regression. Repeated measurements were obtained randomly from about 20% of the sample.

In subjects with unilateral impactions, the maxillary bone area (P = 0.0227) was higher in the impacted side, with a mean difference of 245.5 pixels (SD, 569.2), but the fractal dimension (P = 0.9822) was not, -0.0003 pixels (SD, 0.082). Comparisons of unilateral and bilateral subjects using a general linear mixed model test confirmed the increased bone area in the impacted side (P = 0.1062). The repeated measurements showed similar results.

The maxillary alveolar bone area is increased in the impacted side compared with the nonimpacted side.