Dental occlusion influences knee muscular performances in asymptomatic females.

Some authors claim that occlusal appliances can enhance athletic performance. Therefore this study investigated the influence of dental occlusion on knee muscle strength performance. Twelve healthy female subjects (mean age 24.1 +/- 3.1 years) without temporomandibular joint dysfunction participated in this study. Isokinetic quadriceps and hamstring strength were assessed in relation to three randomized jaw conditions: mouth closed in maximum intercuspidation without splint, mouth closed on a balanced splint which optimized contact over the dental arch, mouth closed on a piece of resin of 1 mm which created an imbalanced occlusion. Tests were performed at 60 degrees /s and 240 degrees /s in concentric and 30 degrees /s in eccentric exertions. Concentric performances did not show any significant difference between the 3 jaw conditions (p > 0.05). By contrast, in the eccentric trials related to quadriceps performance, significant differences (p < 0.05) were observed between the resin condition and the two other modalities (without splint or with a balanced splint). The imbalanced occlusion created by the resin component corresponded to an average decrease of 9% in eccentric peak torque. The eccentric hamstring peak torques also showed a significant difference (p < 0.05) between measurements with splint and with resin (7% decrease when occlusion was imbalanced). In conclusion, among asymptomatic females, artificial imbalanced occlusion induces immediate and significant alteration of knee eccentric muscle performances. Therefore, occlusion examination should be undertaken on a regular and frequent basis for high-level athletes. Moreover, for athletes using mouthguards, muscular performance assessments should be planned with and without the dental protection