Correlation Between Temporomandibular Joint Disc Displacement And Craniomaxillofacial Morphology In Adults

Objective: Studying the correlation between temporomandibular disc displacement and craniomaxillofacial morphology in adults;Analyzing the sagittal and vertical features of adult patients with bilateral temporomandibular disc displacement and exploring the correlation of disc displacement and facial features;through the comparative analysis of patients with bilateral temporomandibular disc displacement at different genders and stages,the effects of gender and stage on the correlation were preliminarily investigated.Methods: A total of 68 adult patients with TMD symptoms who were diagnosed as bilateral temporomandibular joints disc displacement by MRI at the orthodontic department of the Affiliated Stomatological Hospital of China Medical University from 2015 to 2018(including bilateral disc displacement with reduction 30 cases,and the bilateral disc displacement without reduction 38 cases).The control group included 27 cases who diagnosed as bilateral disc normal by MRI,with TMD symptoms in the same period.The cephalometric were measured by Winceph 9.0 software.The data were analyzed by SPSS23.0 software.Two-way analysis of variance was used to investigate the correlation between disc displacement,gender and cranio-maxillofacial morphology,Multiple comparative analysis was used to evaluate the effect of disc displacement stage on craniofacial morphology.Results: The results showed that there was a statistically significant difference in sagittal relationship distribution between DD group and BN group(P<0.05).The results showed that there was no significant difference in vertical relationship distribution between DD group and BN group(P>0.05).The distribution of sagittal and vertical relationship in DD group were different.However,there was no statistically significant difference in the BN group.The proportion of skeletal class II and hyperdivergent malocclusion was higher in the DD group;Between DD group and BN group,only anterior facial height,posterior facial height,anterior facial height/posterior facial height,FH-OP angle,PP-MP showed gender differences(P<0.05).There were no gender differences between the other measures(P>0.05).The DD group was compared with the BN group,the SNB,ANB,the articular angle,A-B to FH,SN-MP,FH-MP,PP-MP,posterior facial height,anterior facial height/posterior facial height,FH-OP,PPMP,the three angle,mandibular ramus height,mandibular ramus inclination,the effective mandibular length and the height of the condyle showed difference,and there is statistically significant;The change of the maxillofacial bone shape from BN,BDDR to BDDNR will be more obviously,and major changes exist in the BDDNR group.Conclusion: Firstly,there is a correlation between temporomandibular disc displacement and the changes of facial morphological features,and there is no correlation between the tooth relationship and temporomandibular disc displacement.The class II,hyperdivergent patients is prone to have temporomandibular joint disc displacement;Secondly,There are gender differences in the anterior height,posterior height,anterior posterior height ratio,occlusal plane angle,PP-MP angle,the three angle and mandible morphometry;Lastly,as the stage of disc displacement developing,the height of the condyle reduces,the mandible rotates backward,the mandibular retraction is aggravated,and the trend of class Ⅱ and hyperdivergent are more obvious.