Objective       To measure alveolar bone thickness in mandibular anterior region of class Ⅱ malocclusion on cone-beam computed tomography (CBCT) sections.        Methods       The CBCT data of 66 cases of class Ⅱ malocclusion (male 32 and female 34) were selected for this study. An irregularity index was used to categorize these data as having mild

moderate

or severe crowding. Then

the following parameters were measured on the sections corresponding to root region of mandibular incisors with the Mimics 9.0 software: labial

lingual

and total alveolar thickness of cortical and cancellous bone on the region of alveolar bone crest and middle root region; labial

lingual

and total alveolar thickness of cortical and cancellous bone on the root apical region

and total cancellous bone thickness and distance between the vestibular and lingual cortices.        Results       The total and lingual cancellous bone thickness of the root apical region were greater in the males than in the females (P0.05). The total

labial cortical and labial cancellous bone thickness of the alveolar bone crest region of the severe crowding cases were greater than those of the mild and moderate crowding cases (P0.05). The total and labial cortical thickness of the alveolar bone crest region of the severe crowding cases were greater than those of the moderate crowding cases (P0.05). Additionally

by using Pearson correlation analysis

significant correlations were determined between incisor crowding and alveolar bone thickness in male and female (|r|0.3).        Conclusion       Significant  correlation is found between the degrees of mandibular incisor crowding and alveolar bone dimensions. Except for the total and lingual cancellous bone thickness of the root apical region

there is no gender differences in basal bone dimensions.