Relationship between abnormal horizontal or vertical dental overlap and temporomandibular disorders

Purpose: This study investigated if abnormal vertical (overbite) and/or horizontal (overjet) dental overlap are more prevalent in adult subjects with clinical signs of temporomandibular disorders (TMD). Methods: Case-control design. The sample comprised 103 subjects, males and females from 19 to 54 year-old, which were divided into two groups: Group 1 (control) without TMD (n=52) and Group 2 (cases) with TMD (n=51). Inclusion criteria for Group 2 were based on axis I of the RDC/TMD protocol. Two calibrated examiners (Cohen kappa = 0.85) performed the clinical examination to collect data on occlusion and TMD. Data were analyzed by Chi-square tests. Results: Overbite mean values were 3.4 mm (control group) and 2.5 mm (cases group). Abnormal overbite was found in 26 subjects (50%) of the control group and 16 (31%) in the cases group (P=0.054). Overjet mean values were 2.4 mm and 2.0 mm for the control and cases groups, respectively. Abnormal overjet was found in 44 (85%) subjects of the control group and 44 (86%) of the cases group (P=0.811). No significant overall association was found between the tested occlusal variables and TMD (P=0.585). Conclusion: Overbite and overjet were not associated with TMD in this sample.