Evaluation of Mandibular Buccal Shelf Area for Mini Screw Placement in Different Sagittal and Vertical Skeletal Pattern: A CBCT Study.

Background: The continuous evolution in orthodontics introduces innovative materials and methods to enhance treatment efficacy. Among these advancements, orthodontic anchorage screws, particularly miniscrews, have revolutionized treatments by offering diverse nonsurgical solutions for managing space discrepancies and certain skeletal malocclusions. The success of miniscrews is influenced by various factors including patient-related factors (age, sex, skeletal pattern, and oral hygiene), miniscrew-related factors (diameter, length, shape), and treatment-related factors (technique, applied forces, and insertion site).

Materials and methods: This study used Cone Beam Computed Tomography (CBCT) to evaluate the mandibular buccal shelf area for miniscrew placement across different sagittal and vertical skeletal patterns in 63 subjects, categorized based on the ANB angle and Jarabak ratio into Class I, II, III, and horizontal, average, and vertical growth patterns, respectively. Measurements were taken at specific sites related to the mandibular first and second molars, focusing on angulation, buccal bone depth (4mm and 6mm from the cementoenamel junction), and buccal bone thickness (6mm and 11mm from the cementoenamel junction).

Results: There were no significant statistical differences in any measurement between the right and left hemiarches. The values for the bone around the distal root of the mandibular second molar were significantly greater than the other values. With regard to Sagittal Skeletal Pattern, Class I cases showed greater values as compared to Class II and Class III with a significant difference in the angulation, bone depth, and thickness at 11 mm from CEJ. Although values tended to be greater in patients with horizontal growth pattern, the difference was not statistically significant.

Conclusion: Mandibular buccal shelf provides an optimal bone site for miniscrew insertion with better osseous characteristics at the distal root of the mandibular second molar. Subjects with skeletal Class I and horizontal growth pattern exhibit the most favorable osseous characteristics in the MBS area. However, in terms of bone thickness at 6 mm from CEJ Class III cases showed significant difference compared to Class I and Class II.