Bone and cortical bone characteristics of mandibular retromolar trigone and anterior ramus region for miniscrew insertion in adults

INTRODUCTION

The aim of this study was to evaluate bone depth, cortical bone thickness, and vestibulolingual bone dimension of the mandibular retromolar trigone and anterior ramus region to evaluate what are its most suitable sites for miniscrew insertion in adults.

METHODS

The sample included cone-beam computerized tomography (CBCT) records of 60 adult subjects retrospectively evaluated. All CBCT examinations were performed with the use of an i-CAT CBCT scanner (Imaging Sciences International). Each exam was converted into DICOM format and processed with the use of Osirix Medical Imaging software. On reproducible sagittal scan views, bone depth and cortical bone thickness were evaluated on specific lines parallel and at a 45° angle to the occlusal plane, and at 3 mm and at 6 mm distance from it. Vestibulolingual bone dimension was computed in 4 different cross-section scans and at 3 different levels of depth (0, 6, and 11 mm).

RESULTS

All of the considered insertion sites showed on average more than 10 mm of bone depth. Inferential statistics showed significantly (P <0.05) greater bone depth (+3 mm) in cross-sectional scans parallel to the occlusal plane compared with those at a 45° angle to it. Cortical bone thickness showed average values from 3 mm to 5 mm. Vestibulolingual bone dimension showed a significant (P <0.05) reduction (-10 mm) in the posterior region of retromolar region. No significant differences were found between subjects with and without third molars.

CONCLUSIONS

The retromolar trigone and anterior ramus region showed enough bone quantity and adequate bone quality for safe miniscrew insertion in adults.