Cortical bone thickness of the adult alveolar process--a retrospective CBCT study.

Objectives: To investigate and compare cortical bone thickness of the posterior alveolar process in adult patients presenting with skeletal Class I, II and III malocclusions.

Methods: Cone beam computed tomographic (CBCT) images of 196 adult subjects, aged 20-45, were evaluated. Cortical bone thickness was measured 4 mm from the alveolar crest, as the shortest bucco-lingual dimension of the cortical bone at interdental sites from the distal of the maxillary canine to the mesial of the maxillary second molar.

Results: There were no differences between the malocclusion groups in mean age, gender, or vertical pattern (p > 0.05). At all sites measured, there were no statistically significant differences in the means of cortical bone thickness between the groups (p > 0.05). Maxillary palatal bone thickness was reduced in the Class I (p < 0.0001), and Class II (p < 0.001) groups; but mandibular buccal thickness increased significantly (p < 0.001) in all malocclusion groups from anterior to posterior.

Conclusions: There was no difference in cortical bone plate thickness between Class I, II and III subjects when related to mini-implant placement sites. As the measurement site moved towards the posterior, maxillary palatal cortical thickness decreased except in Class III cases, while mandibular buccal bone thickness increased in all malocclusion groups.