Evaluation of palatal bone thickness in adults with normal occlusion for orthodontic miniscrews placement

Objective To investigate the palatal bone thickness in adult with normal occlusion Methods The cone beam computerized tomography records of 32 adults with normal occlusion ( 16 males and 16 females), mean age (30. 1 ±6. 5) years, were used to measure the bone thickness at midpalatal area and the right and left palatal sides. Coronal slices at 3 mm intervals were generated. Slice 1 was the coronal slice through the posterior border to the incisive foramen, while Slice 7 was the coronal slice 18 mm away from the incisive foramen. At each coronal slice, the midpalatal sites were Site M and the sites on the exterior margin of the hard palatal were Site D. Four equally divided parts on the line linking Site M to Site D were named Site A, B, C from the interior to the exterior respectively. Palatal bone thickness were measured at these sites. Results Significant differences were noted from Slice 1 to Slice 7, the bone thickness of palate tended to decrease from the front to the back. The thickest site at hard palatal was 12. 6 mm, locating at Site D of Slice 1, while the thinnest site was 2. 7 mm, locating at Site B of Slice 7.The palatal bone thickness ranged from 10. 5 mm(maximum) to 5. 8 mm(minimum) at Slice 2 and Slice 3. No statistical significance was found between the left and right sides ( P ＞ 0. 05 ). Conclusions The favorable sites for miniscrew placement were the anterior region of the hard palate in adult. The length of miniscrew ranged from 5 mm to 10 mm can be placed from 6 mm posterior to the incisive foramen. Key words: Palate, hard;  Orthodontic anchorage procedure;  Bone thickness