Temporomandibular joint repositioning and exercise performance: a double-blind study.

In the present study, the effects of temporomandibular joint (TMJ) repositioning by use of an acrylic appliance on maximum and submaximum physiologic and performance measures were evaluated in seven male and four female volunteers with documented TMJ malalignment. In an attempt to remove design inadequacies of previous research in this area, a double-blind strategy was utilized. Subjects were randomly assigned to each of four conditions: 1) normal, without a bite splint, 2) with a placebo splint with no occlusal contact so as to maintain normal jaw position, 3) with a splint that optimized jaw position, and 4) with a splint that magnified the subjects normal degree of malocclusion. Measurements were taken of visual reaction time and movement time, muscular strength of the grip, elbow flexors, and leg extensors, submaximal and maximal oxygen uptake, perceived exertion, anaerobic power output, and all-out working capacity in both arm and leg exercise on a cycle ergometer. Analysis of variance for repeated measures indicated that in no instance were the differences in mean scores on physiologic and performance measures with TMJ repositioning or placebo statistically significant when compared with the normal condition. This was the case for the group as a whole or when the five subjects with the greatest TMJ dysfunction were analyzed separately. These findings strongly support the contention that the beneficial effects of short-term TMJ repositioning on exercise performance noted in previous reports may be the result of inadequacies in research design and evaluation rather than the true effects of the bite splint.