[Do Changes in Dental Occlusion Influence the Rehabilitation of a Glenohumeral Internal Rotation Deficit (GIRD) in Professional Female Volleyball Players? A Pilot Study]. / Einfluss dentaler Okklusionsveränderungen auf die Rehabilitation eines glenohumeralen Innenrotationsdefizits (GIRD) bei Profivolleyballern.

INTRODUCTION: There have been controversial discussions in research regarding the mutual relationship between changes in dental occlusion and postural reorganisation. Particularly in professional sports, the application of dental splints has been studied increasingly. However, there is a lack of data regarding the effects of a dental splint on the motor function of the shoulder joint, although overhead athletes often have to deal with long-lasting shoulder problems and their consequences. This study aimed to investigate the influence of a change in dental occlusion by means of a dental splint on the rehabilitation of a glenohumeral internal rotation deficit (GIRD) among volleyball players. METHOD: In this study, 22 professional female volleyball players with GIRD and a tROM larger than five degrees were included. Participants were randomised to a splint group (n = 11) and a non-splint group (n = 11). Range of motion and the isometric strength of the dominant shoulder were measured. Shoulder pain and function were investigated by the SPADI assessment, and the functional status of the temporomandibular joints was assessed through the DC/TMD classification. Over a period of eight weeks, both groups received an individual training program. The splint group completed the training program with a dental splint (1-2 mm thick), the non-splint group without a splint. RESULTS: Range of motion: There are no significant differences between the two groups in the range of motion (internal rotation U = 33 000, p = 0.36; external rotation U = 39 500, p = 0.66; GIRD U = 41 000, p = 0.78; tROM U = 41 000, p = 0.78). At the end of the study, none of the volleyball players in the splint or non-splint group had a GIRD > 20 degrees or a tROM difference > 5 degrees. Shoulder strength: No differences were detected between the two groups in force (internal rotation U = 36 000, p = 0.50; external rotation U = 44 000, p = 0.97; elbow flexion U = 28 000, p = 0.18). Only the force of the shoulder quadrant changed significantly (U = 20 500, p = 0.04). Shoulder pain and function (SPADI): No significant differences were found for the SPADI assessment (U = 31 000; p = 0.28). Functional status of the temporomandibular joint (DC/TMD): The DC/TMD assessments also did not change significantly. CONCLUSION: Regarding the secondary hypothesis, a significant change in Q strength was detected. All other parameters (ROM: internal rotation, external rotation, GIRD, tROM; strength: internal rotation, external rotation, elbow flexion; shoulder pain and function: SPADI; TMJ: depression, palpation of masseter muscle and temporalis muscle, TMJ) revealed no significant changes between the two groups. In sum, it can be stated that the use of a dental splint does not significantly influence the rehabilitation of GIRD in volleyball players.