Influence of Vertical Dimension of Occlusion on Peak Force During Handgrip Tests in Athletes

Background: In contact sports, such as martial arts, protection from oral injuries is generally recommended. Several authors have focused on the effects of wearing such oral protective gear on sports performances and, in particular, occlusal devices. Although many studies have shown improvements in athletic performance, especially in maximal isometric strength, to date there is still no consensus on the issue. Objectives: The aim of our study was to evaluate differences in isometric handgrip before and after the application of an occlusal splint (OS) in martial arts athletes. Methods: A repeated measures within-subjects design was adopted for the study. Twenty-five young martial arts athletes, specifically of taekwondo (n = 9), ju-jitsu (n = 10) and karate (n = 6), were enrolled in order to study the effects on handgrip peak force while wearing an occlusal splint under two different handgrip test conditions (OS: with occlusal splint vs. NOOS: without occlusal splint), testing both dominant and non-dominant hands. Results: For the dominant hand, comparisons showed a significant increase in handgrip strength under the OS condition (P = 0.01), whereas no significant differences were found for the non-dominant hand for the whole sample. The differences between the OS and NO OS conditions for the dominant hand were present in taekwondo (+8.33%), ju-jitsu (+1.05%) and karate (+2.97%). However, Bonferroni post hoc test showed statistical significance (P = 0.04) only for the taekwondo group. Conclusions: The benefits found with the occlusal splint were statistically significant only during dominant-hand handgrip tasks. Therefore, realignment of the temporomandibular joint (TMJ) via occlusal splints could play a significant role in increasing handgrip peak force only for the dominant hand.