Purpose: This study assessed the effects of cone-beam computed tomography (CBCT) voxel size and exposure settings on the accuracy of alveolar bone thickness (BT) measurements. Materials and Methods: Seven pig mandibles were scanned using 6 CBCT settings: 200, 400, and 600 μm voxels,each with an ultra-low dose (ULD) and a standard dose (SD) setting. BT was measured at 3 locations on 1 anterior and 1 posterior tooth. These teeth were then scanned using micro-computed tomography (micro-CT), and BT was measured at the same locations. The intraclass correlation coefficient (ICC) and paired t-test were used to evaluate agreement between CBCT and micro-CT measurements. The discrepancy between CBCT and micro-CT measurements was calculated, and repeated-measures analysis of variance (RMANOVA) was used to evaluate the effects of the 6 CBCT settings on BT measurement accuracy. Results: The lowest discrepancy between micro-CT and CBCT was observed with the 600 μm ULD (0.29±0.39 mm), followed by the 200 μm SD (0.41±0.72 mm). When BT was less than 2 mm, the lowest discrepancy occurred with the 200 μm SD (0.29±0.33 mm), followed by the 600 μm ULD (0.32±0.25 mm). The ICC between CBCT and micro-CTdecreased as BT decreased. RMANOVA indicated no significant effect of CBCT settings on measurement accuracy. Conclusion BT measured with the 600 μm ULD was comparable to that obtained with the 200 μm SD. Thediscrepancy between CBCT and micro-CT was notable, especially when BT was less than 2 mm.

Mastoid osteomas of the temporal bone are rare, benign, and usually asymptomatic tumors. However, depending on their size and extension, mastoid osteomas may cause facial palsy, a sensation of ear fullness, pressure-related pain, hearing loss, recurrent external ear infections, and chronic discharge. The etiology of mastoid osteomas is still unknown, but congenital, infectious, and traumatic factors have been proposed. Surgical treatment may be performed with minimal postoperative morbidity. In this article, the authors report a case of a 48-year-old woman seeking orthodontic treatment with an unusual retroauricular protruding mass, including the diagnostic process and differential diagnosis. This case supports the essential role of cone-beam computed tomography to analyze and identify the lesion as a mastoid osteoma.