Clinical relationship between maxillomandibular characteristics and temporomandibular disc conditions in female patients with a skeletal class III pattern

Objectives: To analyze the relationship between maxillomandibular characteristics and the severity of temporomandibular disc displacement in female patients with a skeletal class III (SKIII) pattern. Materials: and Methods: Fifty-seven samples were included. Articular disc conditions were evaluated by magnetic resonance imaging, and 25 cephalometric variables on lateral and postero-anterior cephalograms were measured to determine their maxillomandibular characteristics. The samples were classified into three groups based on the articular disc conditions: (1) normal disc position (NDP), (2) disc displacement with reduction (DDwR), and (3) disc displacement without reduction (DDwoR). The relationship between the maxillomandibular characteristics according to disc condition was examined in both a basic statistical analysis and a multivariate analysis known as principal component analysis. Results: : Kruskal-Wallis and Dunn-Bonferroni tests indicated a significant between-group difference in the deviation of mandibular characteristics seen on the postero-anterior cephalogram. The menton deviation, ramal height asymmetry index, and total mandibular length asymmetry index were significantly larger in the DDwoR group than in the NDP and DDwR groups. Furthermore, using principal component analysis, it was possible to extract all of the cephalometric variables into eight principal components. Only the principal component related to mandibular asymmetry could distinguish the SKIII samples with DDwoR from those in the other groups. Conclusions: : There is a significant relationship between mandibular asymmetry and the severity of disc displacement, particularly DDwoR, in female patients with a SKIII pattern. Clinical Relevance: Etiologic relationship between SKIII patients with asymmetric mandible and the severity of articular disc conditions was significantly indicated in this study.