Cone-beam computed tomography and digital model analysis of maxillary buccal alveolar bone thickness for vertical temporary skeletal anchorage device placement

Introduction: This study aimed to quantify the buccal alveolar bone thickness (BABT) in the maxillary molar region to provide a practical guideline for vertical temporary skeletal anchorage device (TSAD) placement using conebeam computed tomography (CBCT). It also aimed to develop a linear regression model for use in digital models to predict available BABT. Methods: The sample for this retrospective study consisted of 31 sites (24 patients; mean age, 28.75 years; range, 18-44 years) in which vertical TSADs were placed successfully in the maxillary posterior interradicular area during the total arch distalization procedure. BABT was measured at 3 points of the interradicular space using CBCT, and the buccal alveolar region thickness (BART), which included buccal-attached gingival thickness and the buccal alveolar bone, was measured using the digital model. In CBCT, BABT was measured at the most convex point of the lamina dura of the root adjacent to the vertical TSAD mesially, at the most convex point of the lamina dura of the root adjacent to the vertical TSAD distally, and the central point between the mesial and distal points. Three linear measurements were obtained at 2, 4, and 6 mm apical to the alveolar crest: the mesial thickness, the central thickness (central(CBCT)), and the distal thickness. In the digital model, the most convex points of the clinical crowns of 2 teeth adjacent to vertical TSAD and their contact point along with the corresponding Will Andrews and Lawrence Andrews ridge were identified. The horizontal distance paralleling the model base was digitally measured and recorded at 3 positions: the mesial, central, and distal points. Then, the following 3 linear measurements were taken directly on each 3-dimensional dental model: the mesial thickness, the central thickness (central(Model)), and the distal thickness. Results: Both BABT and BART at the central position (central(CBCT), 3.44 mm; central(Model), 6.28 mm) were thicker than at the 2 exterior positions (mesial thickness, 2.16; distal thickness, 2.59 mm; mesial thickness, 2.74 mm; distal thickness, 2.99 mm). BABT was thinnest at 2 mm from the alveolar crest, and there was no statistically significant difference between 4 mm and 6 mm. There was a strong correlation between central(Model) and central(CBCT). Conclusions: The mean BABT and BART at the central position, in which we suggest placing vertical TSADs, were 3.44 +/- 0.69 mm in CBCT and 6.28 +/- 1.11 mm in the digital model, respectively. The minimum BABT and BART at the central position in which vertical TSAD was placed successfully were 2.38 mm in CBCT and 4.25 mm in the digital model. There was a strong correlation between central(CBCT) and central(Model), and we developed a linear regression model that resulted in a useful formula for estimating the actual available BABT at the central position: central(CBCT) = 0.57 x central(Model) - 0.15.