Cortical bone thickness and bone depth of the posterior palatal alveolar process for mini-implant insertion in adults

Introduction: Cortical bone thickness and bone depth are important factors when placing an orthodontic mini-implant. The objective of this study was to investigate both variables for the palatal alveolar process. Methods: Thirty dry human skulls were imaged by using cone-beam computed tomography technology. Two-dimensional slices bisecting the posterior interdental sites were generated, and cortical bone thickness and bone depth were measured at 4, 8, and 12 mm from the alveolar crest. Two-way repeated measures analysis of variance (ANOVA) was used to analyze the measurements. Results: Interdental site and measurement level had a significant impact on both cortical bone thickness and bone depth. Cortical bone thickness was typically greatest at the 8-mm measurement level and more anterior interdental sites. Bone depth decreased with higher measurement levels and was smallest at the most posterior-superior measurement points. Conclusions: Cortical bone thickness and bone depth of the palatal alveolar process are, on average, favorable for the insertion of orthodontic mini-implants; however, some sites should routinely be avoided to prevent damage to the maxillary sinus unless 3-dimensional imaging is available. (Am J Orthod Dentofacial Orthop 2011;140:806-11)