CBCT Maxillary Bone Volume Analysis in Patients With Impacted Canines

Objectives: The normal development and eruption pattern of maxillary canines can be affected by different genetic and environmental etiologic factors. We proposed to evaluate the maxillary alveolar bone volume, pre- and post-orthodontic treatment, in patients with unilateral and bilateral impacted canines using cone beam computed tomography (CBCT). We hypothesized that the side of impaction would present a lesser bone volume than the non-impacted sides.
Methods: Pre-orthodontic and post-orthodontic CBCT scans (n=30, 17 unilateral/13 bilateral) of patients with an average age of 14.63 (SD=3.89). CBCTs settings were: 170.00FOV,120kV, 5mA, 4s exposure, and 0.3mm. Segmentation was performed utilizing the Invivo 5.4 software in the coronal and horizontal views using sagittal (incisive canal), posterior (pterygomaxillary suture), superior (zygomatic process) and inferior (cementoenamel junction) limits. Volume calculations were made after adjusting to a threshold that limited noise and optimized the alveolar bone. Each side of the maxilla was measured three times and the average value was used for statistical analysis. About 20% of the sample was remeasured for reliability. Multiple linear regression analysis was utilized for comparison of variables.
Results: Regardless of the impaction category, the right side of the maxilla had a greater average volume than the left side, 7980mm³ compared to 7659mm³ (p=0.0078). In unilateral pre-treatment scans less bone volume was observed on the impacted side with a mean difference of -198.2 (SD=431.1), but not significantly (p=0.0763). Changes in the volume over the treatment period were variable, the average change in bilateral cases was 122.4mm³ (SD=1136.2) on the right and -29.8mm³ (SD=1135.3) on the left.
Conclusions: Our results suggest that a decreased maxillary volume may not be associated with canine impaction.