Optimal sites for mini-implant insertion into the infrazygomatic crest according to different craniofacial morphologies: A cross-sectional cone-beam computed tomography study.

Introduction: The infrazygomatic bone crest and other extraalveolar regions represent a viable option for the placement of temporary anchorage devices when distalizing the maxillary arch. This approach allows for the movement of the dentition without concern for potential collisions among dental structures. Nevertheless, it is of the utmost importance to conduct a thorough examination of the anatomy of this region before the placement of mini-implants to prevent potential injuries, such as maxillary sinus perforations. The objective of this study was to quantify the depth of the infrazygomatic crest and evaluate its correlations with age, gender, skeletal classification, and vertical pattern.

Methods: The study sample of this cross-sectional, retrospective study consisted of 201 cone-beam computed tomography scans collected from patients treated at the master's program in orthodontics at the University of Valencia and at a private dental clinic. The cone-beam computed tomography scans were collected for 5 years, from January 2017 to May 2022. The total and intraalveolar lengths were defined and measured at 3 points: the distal roots of the maxillary second molars, the distal roots of the maxillary first molars, and the mesial roots of the maxillary first molars. These measurements were taken on both the right and left sides using the Carestream 3D Imaging System (Atlanta, Ga).

Results: The total length (TL) at the mesiobuccal level of the first molars was found to be significantly longer on both sides (P = 0.001). The intraalveolar length exhibited statistically significant differences between the right and left sides, with those of the left side exhibiting greater length (P <0.001). The normodivergent patterns demonstrated lower TL values than hypodivergent (P = 0.006) and hyperdivergent patterns (P = 0.033).

Conclusions: A statistically significant inverse relationship was observed between the distance from the cementoenamel junction to the vestibular bone crest and the total and intraalveolar lengths in the studied regions. The TL was greatest in the region of the mesiobuccal root of the maxillary first molars, followed by the region of the distal root of the second molars, and finally, the region of the distobuccal root of the maxillary first molars. Patients with normodivergent patterns exhibited the lowest total infrazygomatic ridge height.