Qualitative and quantitative evaluation of the palatal posterior supra alveolar bone region for miniscrews placement

Abstract

This study aimed to evaluate the total bone thickness, the cortical bone thickness, and the mucosa depth of specific site that we define Palatal Posterior Supra Alveolar Bone (PPSAB), for the miniscrews insertion. The sample included CBCT records and digital models of 23 subjects (17F 6M age mean 32) retrospectively evaluated. Digital dental casts were superimposed with CBTC. Total Bone thickness, cortical bone, and mucosa depth were evaluated at the first molar upper level. The measurements were performed in coronal view, the scans were evaluated mesially, infraradicularlly, and distally to the first molar. Each scan was considered at four levels in the apico-coronal direction (-4 mm, -2 mm, 0 mm, +2 mm) for a total of 36 measurements per subject. The total bone thickness decrease moves from mesial insertion sites to distal ones. Moreover, it increases in the coronal insertion sites compared to the apical at all the anteroposterior levels. However, at -4 mm (the most apical site evaluated) the total bone thickness decreases due to the proximity to the first molar root. The insertion site with the greatest average total bone thickness (8.68 mm) was mesial to first molar 2 mm apical to the corner palatal point (0 mm). The palatal posterior supra alveolar bone (PPSAB), could be a suitable site for the orthodontic miniscrews insertion in the majority of orthodontic adult patients. However, great variability was observed among different considered subjects. Cortical bone thickness is less than 2 mm. Palatal mucosa was on average more than 4 mm.