GE Huaizhi,CHEN Jiuzun,XU Lei, et al. The effect of temporomandibular joint disc injury on masticatory muscle structure in adolescents: An MRI-based study[J]. JOURNAL OF WEZHOU MEDICAL UNIVERSITY, 2023, 53(8): 657-661.
Abstract：Objective: To study the effect of temporomandibular joint disc injury on masticatory muscle structure in adolescents, and to explore the diagnostic value of MRI in temporomandibular disorder (TMD). Methods: A total of 42 patients who received MRI examination of temporomandibular joint in the Second
Affiliated Hospital ﹠ Yuying Children’s Hospital of Wenzhou Medical University from April 2019 to December 2020 were collected as research subjects. All patients underwent MRI examination of temporomandibular joint at 3.0T, and were diagnosed as unilateral disc displacement without contralateral displacement through routine sequence images. T2-mapping and 3D-CUBE T2 sequences were scanned. The joint disk T2 values were measured on the T2-mapping sequence. The cross-sectional area and the height of 3 pairs of masseters, i.e. internal pterygoid muscles, external pterygoid muscles and masseter muscles were measured by multiplane recombination on the 3D-CUBE T2 sequence images, and their relative volume was calculated. Paired t test was used to compare the cross-sectional area, height and relative volume of masticatory muscles as well as the T2 value between the injured side and the control side. Pearson correlation analysis was used to study the correlation among the cross-sectional area difference, height difference, and relative volume difference of masticatory muscles with differences between the injured and control sides. Pearson correlation was also used to analyze the correlation between the difference of the cross-sectional area, height and relative volume of the masticatory muscle on the injured side and the control side and the difference of the articular disk T2 value. Results: Compared with the control side [(435.60± 99.28)mm2], the cross section of masseter muscle on the injured side [(412.66±106.40)mm2] decreased (P<0.05), and compared with the control side [(31.77±8.83)cm3], the relative volume of masseter muscle on the injured side [(29.79±9.91)cm3] decreased (P<0.05). The T2 value on the injured side [(32.06±3.86)ms] was lower than that on the control side [(36.45±5.48)ms] (P<0.001). There was a high positive correlation between the difference in cross-sectional area and relative volume of the masseter muscle on the injured and control sides (r=0.930, P<0.001). Conclusion: The masseter muscle of the healthy side is more developed than that of the affected side in patients with TMD. It is inferred that the masseter muscle of the affected side may be an indirect imaging feature of TMD before symptoms appear. The enlarged masseter muscle on the affected side may be an indirect imaging feature of TMD.
