Cone beam computed tomographic analysis of the spatial limitation during mandibular arch distalization

BACKGROUND: In the literature, attempts are seldom made to quantify spatial limitation during mandibular arch distalization. This study aimed to investigate the spatial limitations associated with cortical contact with the mandibular second molar during mandibular arch distalization. METHODS: The study population included 67 individuals who had undergone cone beam computed tomography (CBCT) (34 male and 33 female; mean age: 23.9 ± 2.72 years). The total ridge width, alveolar housing width, and root width were measured to evaluate the buccolingual limit. The space distal to the molar root represented the mesiodistal limit. The influence of sex, right versus left side, root-contact condition, malocclusion category, and presence of wisdom teeth were evaluated. RESULTS: The rate of cortical contact was 49.3% before any orthodontic movement. No significant differences were observed in the alveolar width according to sex (male vs female), side assessed (right vs left), wisdom teeth (present vs absent), or malocclusion category. The ridge width and the alveolar width were smaller in the contact group than in the non-contact group (P < 0.01). The group with wisdom teeth showed a larger available distalization distance, but a significant difference was observed only near the alveolar crest. CONCLUSIONS: Both ridge width and available distalization distance were limiting factors for mandibular teeth distalization. For cases in which whole-arch distalization is planned, CBCT is recommended before treatment, especially for non-extraction treatment. This approach ensures safe and predictable tooth movement.