The influence of dental occlusion on hamstring muscle isokinetic parameters in active competitive soccer athletes: a randomized controlled trial.

Introduction: The improvement of athletic performance depends on numerous factors including physical health, training status, neuromuscular coordination and psychological state. In recent years, the influence of dental occlusion and jaw position has gained increasing attention. The influence of occlusal bite splints (BS) on the improvement of motor performance, which is related to postural balance, has been the focus of many investigations. However, the extent of impact, that BS can have on muscle strength, has been attested to be unknown. Therefore, we wanted to investigate the influence of occlusion on the isokinetic strength parameters of the thigh muscles. Methods: Thirty active male competitive athletes at 18-32 years were included in this study. None had a gnathological or physiological disease. The subjects were randomly assigned to two experimental groups of 15 participants each, using a cross-over design. Concentric isokinetic muscle force measurements of the quadriceps and hamstring muscles were performed using a dynamometer under three occlusal conditions: habitual occlusion (HO), harmonic bite splint (HS), and simulated interference contact/malocclusion (MO). The three muscle force measurements were completed twice, each with one repetition at extension (E) and flexion (F) of the right knee, maximum force, and an angular velocity of 120°/s. Between the measurements, 120 s were scheduled for muscular recovery. The splint (HS) was 3D printed from a methacrylate-based resin and the harmonic occlusion was verified using the T-Scan Novus and occlusal paper. A unilateral punctual malocclusion (MO) made of light-curing methacrylate was individually placed in region 16. Statistical analysis was performed with one-factorial analysis of variance (ANOVA) followed by Results: There was a significant decrease in maximum torque (Nm) and muscle work (J) during extension movement with the simulated MO is compared to HO and to HS. Muscle power (W) was also decreased with MO compared to HO and HS. In the flexion movement, a significant decrease in muscle power was observed in the MO condition compared to the HS condition. No significance, but a tendency for improvement in extension and flexion movement in maximum torque, muscle work, and muscle power were determined in the HS condition compared in the HO condition. Conclusion: Our results indicate that simulated interfering occlusal contact can lead to a significant decrease and balanced occlusion to a tendency for improvement of isokinetic performance parameters in young, well-trained soccer players. This underlines a presumed importance of a balanced occlusion for muscle performance, especially in terms of maximum strength, muscle work and muscle power. The results show a functional relationship between dental occlusion and the lower extremities, which reflects an underlying anatomical connection in which the central nervous system may play a major role. Clinical Trial Registration: ClinicalTrials.gov, identifier, DRKS00030990.