# Anatomical Variations of the Mandibular Buccal Shelf According to Sex, Facial Biotype, and Root Reference: A CBCT Study

## TL;DR

This study uses CBCT scans to assess the best anatomical site for placing orthodontic mini-implants in the mandibular buccal shelf based on sex and facial biotype.

## Contribution

Identifies the distal root of the mandibular second molar as the most favorable site for mini-implant placement, considering anatomical variations.

## Key findings

- The distal root of the mandibular second molar has the highest bone dimensions for mini-implant placement.
- Males show slightly greater bone dimensions compared to females in specific measurements.
- Brachyfacial patients have the highest bone averages despite no significant differences among facial biotypes.

## Abstract

To evaluate, through cone-beam computed tomography (CBCT), the anatomical characteristics of the mandibular buccal shelf according to sex, facial biotype, hemiarch, and reference root, in order to determine bone availability for orthodontic mini-implant placement.

A cross-sectional observational study was conducted on 60 CBCT scans (480 roots) of patients aged 12-53 years. Measurements of angulation, horizontal bone thickness (4 mm and 6 mm), and vertical bone height (6 mm and 11 mm) were obtained at the mesial and distal roots of the mandibular first and second molars. Statistical analyses included t-test and one-way ANOVA (p < 0.05).

The distal root of the mandibular second molar exhibited the highest bone dimensions (angulation 37°, horizontal thickness 17.3 mm at 4 mm and 10.0 mm at 6 mm, vertical height 5.4 mm at 6 mm and 6.7 mm at 11 mm), establishing it as the most favorable insertion site. In contrast, the mesial root of the first molar showed the lowest values. Sex-related analysis revealed slightly greater dimensions in males, with significant differences in horizontal thickness at 4 mm and vertical height at 11 mm (p = 0.05). No statistically significant differences were observed among facial biotypes or between hemiarches, although brachyfacial patients consistently showed the highest averages.

The distal root of the mandibular second molar represents the most reliable anatomical site for mini-implant placement in the buccal shelf, regardless of sex or facial growth pattern. CBCT assessment remains essential for individualized planning and to minimize complications.