CBCT-based simulation of mandibular buccal shelf miniscrew insertion: Influence of angulation, facial pattern, sex and side on simulated miniscrew trajectory length: A retrospective study.

AIM: To evaluate simulated miniscrew trajectory length in the mandibular buccal shelf (MBS) area in order to identify the most suitable site for miniscrew placement at different insertion angles. Effects of side, sex, and facial pattern were also investigated.

MATERIALS AND

METHODS

Cone-beam computed tomography (CBCT) scans of lower arches from 60 patients, recruited between January 2018 and December 2022, were retrospectively analysed. The sample was divided into three subgroups according to vertical facial pattern. Miniscrew insertion was simulated at two distances from the cementoenamel junction (CEJ) (4 and 6mm) and at three inclination angles (70°, 80°, and 90°). Statistical analyses were performed to detect any differences related to sex, facial pattern or side. Subsequently, a step-by-step analysis was conducted to determine the site for miniscrew insertion with simulated miniscrew trajectory length, and an anatomical description of this area is also provided. Statistical significance was set at P<0.05.

RESULTS

Overall, bone thickness and depth showed a consistent tendency to increase distally and apically, regardless of insertion angle. No clinically significant differences were observed between sides, while sex differences were noted in only two measurements. Differences among facial patterns were detected for approximately 25% of the measurements. The most favourable sites for miniscrew placement in the MBS area were located near the lower second molar.

CONCLUSIONS

The disto-buccal aspect of the second molar, at 4mm from the CEJ and 80°, with a mean value of 16.49±4.83mm, offers the most favourable conditions for miniscrew placement, although others are possible. Pre-drilling is recommended to reduce fracture risk.