Relationship between Occlusal Factors, Oral Parafunctions and Temporomandibular Disorders: A Case Control Study

Aims: The purpose of this study was to assess the multifactorial etiology of temporomandibular disorders (TMD). To this end, prevalence of occlusal factors and parafunctional habits was investigated and correlated in two groups: patients with TMD (case group) and patients without TMD (control group). Methods: Prevalence of 7 static and 4 dynamic malocclusion features, and some parafunctional activities (nail biting, teeth grinding, teeth clenching, lips and cheeks biting, pens chewing, mandibular jaw moves habit…) were recorded in the two groups. Case group consisted of 30 patients with a diagnosis of myofascial pain, with or without limited opening, and/or disk displacement with or without reduction. Control group consisted of 30 patients without TMD. Univariate and multivariate analysis were used to identify the significant associations between occlusal variables, oral parafunctions and temporomandibular disorders. Results: All patients in case group, and 93.3% in control group had at least one malocclusion, and a statistically significant association between TMD and three malocclusions (two dynamic malocclusion features: mediotrusive interferences, laterotrusive interferences, and one static malocclusion: overbite >4 mm) was shown. Regarding parafunctional activities, all patients in case group, and 93,3% in control group had at least one parafunction, and the mean number of parafunctions per patient was significantly higher in case group than in control group. Besides, an association between TMD and some parafunctions was shown. Conclusion: Given the multifactorial nature of TMD, a behavioral reeducation to reduce parafunctional activities could be the first phase of the care for TMD patients and could prevent TMD development. Besides, special attention should be given to normocclusion criteria. These criteria must be fulfilled for any dental care.