Three-dimensional condylar positions and forms associated with different anteroposterior skeletal patterns and facial asymmetry in Chinese adolescents

Abstract

Objective. To evaluate the association of condylar asymmetry and chin position with different anteroposterior skeletal patterns using three-dimensional models reconstructed from cone-beam computed tomography (CBCT) images. Materials and methods. CBCT scans of 123 Chinese adolescents (aged 11–15 years, 68 girls and 55 boys) with 64 skeletal Class I, 46 Class II and 13 Class III were selected from scans of patients attending the orthodontic clinic. The condyles of the subjects were reconstructed bilaterally and 25 linear, angular and volumetric measurements were performed to evaluate the asymmetry of the condyles and position of the chin. The proportions of condylar asymmetry in the different skeletal groups were calculated by the absolute difference value between the left and right sides to the smaller side value. One-way analysis of variance and Pearson's correlations were used to analyse the data. Results. The values for RV, RCL, LCH, RCH, LCGM, RCGM, LCo-Me and RCo-Me were significantly different among the three skeletal groups (p < 0.05). There were significant positive correlations between Pog-Ss and Co-Sh, Co-Me in the Class I and II groups (p < 0.05). Asymmetries for Co-Ss, Co-Sh, CP and SP between the left and right condyles exceeded a ratio of 20% for more than 30% of the subjects. Conclusion. Condylar asymmetry varied significantly among the three skeletal groups, with the vertical position of the condyle (Co-Sh) and height of the mandibular ramus (Co-Me) being significantly and positively related to the chin position.

Key Words::

• CBCT
• condylar asymmetry
• 3D reconstruction
• anteroposterior skeletal patterns

Acknowledgements

This study was supported by the National Natural Science Foundation of China (81000457), Natural Science Foundation of Jiangsu Province (BK2010529) and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (2011-137). The funding agencies had no roles in the study design, data collection and analysis, decision to publish and preparation of the manuscript. The editorial assistance of Professor Roger Smales, The University of Adelaide, South Australia, was greatly appreciated.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.