Occlusal Factors associated with Temporomandibular Disorder based on a Prospective Cohort Study of Young Adults

In this prospective cohort study, mandibular movement analysis was conducted together with clinical examinations to determine the intrinsic occlusal factors that might contribute to the development of TMD. Since mandibular movement analysis has never been conducted previously in this type of cohort study, our results highlight the important implications of occlusal factors potentially associated with TMD. Abstract Purpose: To determine the relationship between temporomandibular disorders (TMD) and the occlusal contact pattern, we conducted occlusal analysis in a prospective cohort study. Methods: One hundred forty-six volunteers consisting of 98 males and 48 females with a mean age of 20.0±1.9 years selected from the dental students of Iwate Medical University were enrolled for the study. All the subjects were asked to fill out a self-adminis-tered questionnaire to screen their general and oral health conditions, and then clinical examination, including evaluation of the occlusal contact pattern, was conducted during the first year. A second clinical examination was repeated 2.5 years later to ascertain the incidence of symptoms of TMD. The natural course of TMD symptoms in the 128 subjects were as follows: group, group, remission group, and continuation group. lateral mandibular types: ④ non-working side molar guided occlusion (NM; n=4), and ⑤ incisal guided occlusion (IG; n=5). Results: In the second examination, 18 out of the 84 subjects (21.4%) who showed no symptoms at the time of enrolment into the study reported TMJ click and/or pain. Of the total, 23, 11, 1, and 1 subjects with symptoms of temporomandibular joint origin were classified as having the CG, WM, NM, and BG pattern of occlusal contact, respectively. With CG as the standard, the relative risk of TMD in subjects shown the WM pattern was 2.79 (95%CI: 1.16 – 6.70). Conclusion: Since the group showing the working side molar guided occlusion pattern showed a high risk of future development of TMJ click and/or pain, lateral excursion guidance may be a contributing factor for the development of TMD.