Relationship between Mandibular Function and Temporomandibular Disorder Symptom over 2.5 years in Young Adults

目的：为探讨颞下颌关节紊乱病（Temporomandibular Disorder，TMD）的内在影响因素，采用前瞻性队列研究方法，对341名青年学生进行了为期2.5年的TMD症状调查（男234人，女107人;平均年龄20.5±2.2岁）在岩手医科大学进行了各种测试，如临床发现，包括TMD症状，牙齿状况，日常生活方式，心理问卷，下颌运动，测定咀嚼肌肌电图（EMG）、咀嚼肌压痛阈（PPT）。在2.5年后进行随访研究，以TMD症状为因变量，将所有的预测值进行Logistic回归分析。通过去除与结果负相关的贵重物品，逐步简化模型。1）在341名被试中，有14名被试在初次就诊时出现TMD症状，2.5年后又有18名被试出现TMD症状。（比值比为1.1-14.7，95%置信限）和TMJ健全（OR为1.8-13.1）与TMD的发生有显著相关性。3）PPT的不对称指数，有症状组与无症状组在习惯性开合运动时的肌电功率谱变化模式和髁突平移量有显著性差异（P<0.05;结论：虽然一些有价值的指标与TMD有关联，但预测价值在本研究中还没有得到证实。由于5年的随访正在进行中，预计将进行更详细的分析。

Objectives: To find the intrinsic contributing factors on Temporomandibular Disorder (TMD), prospective cohort study of TMD symptoms were carried out over 2.5 years in young adults.Methods: Customized questionnaire containing 43 items were utilized to grasp TMD symptoms and general health conditions in 341 students (234 males and 107 females; mean age of 20.5±2.2 years old) in Iwate Medical University Various tests such as clinical findings including TMD symptoms, dental status, daily life style, psychological questionnaires, jaw movements, masticatory muscle electromyogram (EMG), pressure pain threshold (PPT) in masseter muscles were also evaluated. Then, a follow up study was performed 2.5 years later.All of the predictor valuables were used in a logistic regression model with TMD symptoms as the dependent valuables. The model was simplified in a stepwise fashion by removing valuables which were negatively associated with outcome.Results:1) Out of 341, 14 subjects showed TMD symptoms at the initial visit of this survey and 18 more subjects were found to show the symptoms 2.5 years later.2) Daily clenching behavior awareness (odds ratio of 1.1-14.7 in 95% confidence limit) and TMJ sound (odds ratio of 1.8-13.1) had significantly related to TMD symptoms.3) Asymmetry index of PPT, power spectral changing pattern of EMG and condylar translation during habitual open-close movement were the distinctive valuables that showed significantly difference between symptomatic and asymptomatic groups (p<0.05; Dunnett's multiple comparison test).4) There was no significance between the TMD and psychological questionnaire results.Conclusions: Although some valuables showed association to the TMD, predictive valuables were not confirmed yet in this study Since 5 year-follow-up is processing, more detailed analysis over year will be expected.