Aim: To compare and evaluate alveolar bone level and cortical bone thickness Pre and Post alignment of crowded mandibular incisors in non-extraction cases using CBCT.

Methods: We used 27 prealignment and postalignment cone-beam computed tomography images (13 female and 14 male subjects; average age, 16-30 years; average treatment time, 6±2 months) to measure cortical bone thickness, ridge thickness, distance from the apex to the labial cortical bone, and the distance from the cementoenamel junction to the marginal bone crest. Changes in the cementoenamel junction to the marginal bone crest distance were correlated with pretreatment measurements and treatment changes.

Results: Although there were great variations, the average facial vertical bone loss was 0.16±0.11 mm, average decrease in the mid-root level cortical bone thickness by 0.21±0.04 mm on lingual side of the alveolar bone, decrease in the mid-root level ridge thickness of the mandibular central incisors by 0.21±0.17 mm, decrease in apex-level ridge thickness of the mandibular central incisors by 0.32±0.15 mm, increase in the cortical bone thickness from apex to internal border of labial cortical bone mandibular lateral incisors by 0.8±0.07 mm.