Wei Fan1, Deguo Gao2, Yuting Wang1, Yutong Chen1, Yusheng Li1, Zhendong Wang1, Shijun Lu3. 1. Jiangsu Key Laboratory of Oral Diseases, Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China. 2. Zhenjiang Stomatological Hospital.Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, No.81 Yunhe Road, Runzhou District, Zhenjiang City, Jiangsu Pro, China. 3. The Affiliated stomatological Hospital of Soochow University, Suzhou Stomatological Hospital.Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Suzhou, China.
Abstract
OBJECTIVE: To investigate the morphological characteristics of the mandible in subjects with impacted mandibular second molars by measuring and analyzing the mandible in three dimensions. SETTING AND SAMPLE POPULATION: In this retrospective study, the data of a total of 52,609 subjects who underwent cone-beam computed tomography (CBCT) for diagnosis and treatment were reviewed. According to the inclusion and exclusion criteria, 183 subjects with impacted mandibular second molars and 176 age- and sex-matched controls were included. METHODS: A retrospective case-control study was designed. The 183 subjects were divided into two groups: group 1 (G1) comprised 120 patients with unilaterally impacted mandibular second molars, and group 2 (G2) comprised 63 patients with bilaterally impacted mandibular second molars. Group 3 (G3) contained 176 age- and sex-matched controls. The mandible was reconstructed with nineteen landmarks using Mimics software. Twelve linear lengths and 3 angles were measured. RESULTS: The bilateral germination gap, mandibular body width and gonion width in G1 were significantly lower than those in G3 (P < 0.05), while the gnathion angle and first molar width values in G1 were significantly higher than those in G3 (P < 0.05). The results in G2 were similar to those in G1, but the differences between G2 and G3 were greater than those between G1 and G3. There were no significant differences in the other measurements among the groups. CONCLUSION: The mandibles of the subjects with impacted second molars were constricted in terms of the sagittal length and transverse width. This article is protected by copyright. All rights reserved.
OBJECTIVE: To investigate the morphological characteristics of the mandible in subjects with impacted mandibular second molars by measuring and analyzing the mandible in three dimensions. SETTING AND SAMPLE POPULATION: In this retrospective study, the data of a total of 52,609 subjects who underwent cone-beam computed tomography (CBCT) for diagnosis and treatment were reviewed. According to the inclusion and exclusion criteria, 183 subjects with impacted mandibular second molars and 176 age- and sex-matched controls were included. METHODS: A retrospective case-control study was designed. The 183 subjects were divided into two groups: group 1 (G1) comprised 120 patients with unilaterally impacted mandibular second molars, and group 2 (G2) comprised 63 patients with bilaterally impacted mandibular second molars. Group 3 (G3) contained 176 age- and sex-matched controls. The mandible was reconstructed with nineteen landmarks using Mimics software. Twelve linear lengths and 3 angles were measured. RESULTS: The bilateral germination gap, mandibular body width and gonion width in G1 were significantly lower than those in G3 (P < 0.05), while the gnathion angle and first molar width values in G1 were significantly higher than those in G3 (P < 0.05). The results in G2 were similar to those in G1, but the differences between G2 and G3 were greater than those between G1 and G3. There were no significant differences in the other measurements among the groups. CONCLUSION: The mandibles of the subjects with impacted second molars were constricted in terms of the sagittal length and transverse width. This article is protected by copyright. All rights reserved.