Gender Differences in Associations Between Occlusal Support and Signs of Temporomandibular Disorders: Results of the Population-Based Study of Health in Pomerania (SHIP)

Purpose: The aim of this study was to investigate whether gender-dependent associations exist between signs of temporomandibular disorders (TMD) and occlusal support. Materials and Methods: Stratified by gender, the data of 2,963 35- to 74-year-old participants from the epidemiologic Study of Health in Pomerania were used in logistic regression analyses with temporomandibular joint (TMJ) tenderness and muscle tenderness as the dependent variables. Occlusal support was classified according to the Eichner index, a classification system based on occluding pairs of teeth. The final model was adjusted for bruxism, age, and various sociodemographic data. Results: Logistic regression analyses revealed increased odds ratios for TMJ tenderness in men with loss of all four molar and premolar supporting zones (odds ratio 3:9) and without antagonist contact (odds ratio 2:7). Significant relationships in men were also found between muscle tenderness and loss of one (odds ratio 2:1), three (odds ratio 2:1), or four supporting zones (odds ratio 2:7), and loss of any tooth contact (odds ratio 2:3). In women, significant associations between occlusal support and TMD signs were absent. Subjects with bruxism were more likely to have TMJ tenderness (odds ratio women 2:0, men 1:9). In women, an additional relationship existed between bruxism and muscle tenderness (odds ratio 1:7). The following habits showed no significance: gum chewing, unilateral chewing, and lip/tongue/cheek biting. Conclusion: Only in men was the loss of occlusal support significantly associated with muscle and TMJ tenderness. The association between bruxism and TMD signs supports the theory that repetitive adverse loading of the masticatory system may cause functional disturbances.