RESUMO
OBJECTIVE@#To study the developmental and morphological characteristics of the mandible in patients with impacted mandibular second molar and to predict the possible trend of mandibular development via three-dimensional (3D) measurement and analysis.@*METHODS@#A total of 88 cases of impacted group and 88 cases of control group were screened out. 3D measurements were performed by using Mimics software. A total of 23 landmark points and 17 measurements were determined. The measurements were analyzed by t-test.@*RESULTS@#The mandible length, the space between the first molars, the space between mandibular angles, and the width between the first molars in the impacted group were lower than those in the control group (P<0.05). Moreover, the value of the submandibular angle was higher than that in the control group (P<0.05).@*CONCLUSIONS@#The impacted mandible of patients with mandibular second molar showed lack of sagittal and width development, and the impacted mandibular second molar was a manifestation of its degeneration.