Assessing Best Locations for Mini-Implants in the Mandibular Symphysis Based on Different Mandibular Growth Patterns: A CBCT Study

Objective: The aim was to evaluate optimum site for insertion of orthodontic mini-implants at mandibular symphysis in patient with different mandibular growth patterns using cone-beam computed tomography (CBCT). The objectives were to evaluate and measure complete bone width (CBW) and cortical bone width (CtBW) in the symphysis area at various heights [2 mm, 4 mm, 6 mm, 8 mm, 10 mm, and 12 mm from cementoenamel junction (CEJ)] and at various angles (0º, 10º, 20º, 30º, 40º, 50º, and 60º to the occlusal plane), and to assess the effect of mandibular growth patterns (low, average, and high angle) on these measurements. Methods: The study sample included 45 patients aged 16-30 years. Patients were categorized into three groups (n=15) corresponding to the mandibular growth pattern for the assessment of CBW and CtBW. Individual data for each patient were entered into a master table in Microsoft Excel and subjected to statistical analysis using SPSS version 22.0. Analysis of variance was applied to investigate the influence of insertion location, facial type, insertion height and insertion angle on overall bone thickness and CtBW. A p-value <0.05 was considered statistically significant. Intra-observer reliability was assessed using the intraclass correlation coefficient. Results: CBW was notably greater in patients with a low-angle mandibular growth pattern than in patients with other mandibular growth patterns at insertion heights of 8, 10, and 12 mm. CtBW was greater in cases with a low-angle mandibular growth pattern than in cases with other mandibular growth patterns. Similar results were observed for CtBW. Conclusion: The mandibular symphysis in patients with a low-angle growth pattern provides more favorable anatomical conditions for mini-implant placement. The ideal insertion site lies between 6 and 10 mm below the CEJ of the central incisors, with angulation ranging from 0° to 60° relative to the occlusal plane. CBCT assessment should be considered essential in treatment planning to customize implant positioning based on individual growth patterns, thereby enhancing implant stability and success.