Optimizing Infrazygomatic Miniscrew Insertion Parameters: Systematic Review and Meta-Regression Analysis of Bone Thickness by Insertion Height, Angulation, and Anatomical Position

Introduction: Infrazygomatic crest (IZC) miniscrews are widely used for skeletal anchorage in orthodontics. Despite their growing popularity, the optimal insertion parameters—such as height, angulation, and anatomical position—remain controversial, with existing studies offering inconsistent and fragmented data. Aim: To determine the optimal insertion position, height, and angulation of infrazygomatic miniscrews to maximize bone insertion using cone-beam computed tomography (CBCT) analysis and to investigate the influence of facial skeletal patterns on IZC bone morphology. Methods: This review was conducted according to the PRISMA 2020 guidelines. A comprehensive electronic search was performed across six databases: PubMed, Scopus, Web of Science, Cochrane, EBSCO, and Google Scholar. Studies reporting CBCT-based IZC bone thickness were included. A meta-analysis was conducted using a random-effects model, and meta-regression was applied to assess the relationship between insertion height, angulation, and bone thickness. The STROBE checklist was used to assess the quality of the included observational studies. Results: Seventeen studies comprising a total of 1840 CBCT-based measurements were included. The meta-regression revealed a significant inverse relationship between insertion height and bone thickness (β = −0.53; p < 0.001) and a positive correlation with angulation (β = 0.09; p < 0.001). The U67 region refers to the anatomical area between the maxillary first and second molars, adjacent to the infrazygomatic crest and zygomatic buttress, which with an insertion height of 9.9 mm and 80° angulation, demonstrated the highest mean cortical bone thickness (3.52 mm). There was no evidence of a significant association between facial pattern and bone thickness (p = 0.878). Conclusions: This review presents the first predictive model for IZC miniscrew placement based on meta-regression. The findings support the U67 site at 9.9 mm height and 80° angulation as the optimal insertion protocol. These data-driven guidelines provide clinicians with practical, evidence-based direction for improving miniscrew stability and minimizing complications.