Effect of occlusal splint on masticatory movement in healthy individuals

Prediction of Ergogenic Mouthguard Effects in Volleyball: A Pilot Trial

Dental occlusion may affect static and dynamic balance. The effects of a mouthguard on pinpoint accuracy in volleyball were investigated in 28 players who completed a volleyball specific test. Also, masticatory electromyographic tests were performed. The mean pinpoint accuracy was significantly higher with a mouthguard (68.6±9.3 vs. 64.0±7.0 points from 100; p< 0.006). However, differential mouthguard effects were seen, and three subgroups were classified: Group 1 (markedly improved pinpoint accuracy), Group 2 (improved pinpoint accuracy), and Group 3 (reduced pinpoint accuracy). Group 1 had a high masseter resting tone, the masseter activity was low in MVC (maximum voluntary clench) and increased in BOC (maximum bite on cotton rolls; p< 0.04). This indicates a masseter weakness, which would be compensated by a mouthguard. In Group 2, the masseter activity in MVC was high-normal with an imbalance which was improved in BOC (p< 0.01), indicating a possible mouthguard benefit. In Group 3, MVC and BOC were in a high-normal range and showed no relevant deficits. In these subjects the mouthguard had adverse effects. Overall, subjects with masticatory deficits had a benefit from the mouthguard in pinpoint accuracy. Positive or negative mouthguard responders may be detectible from electromyographic tests.

Increase of condylar displacement between centric relation and maximal habitual intercuspation after occlusal splint therapy

The present study assessed condylar displacement between initial maximal habitual intercuspation (MHI) and centric relation (CR), recorded after using a deprogramming occlusal splint for an average period of 7.8 +/- 2.1 months prior to any orthodontic treatment. The sample consisted of 22 subjects, 11 male and 11 female, with an average age of 14.2 +/- 1.4 years, with Class II malocclusion and with no apparent signs or symptoms of temporomandibular dysfunction (TMD). Condylar displacement was measured using a Panadent axis position indicator in decimal fractions of a millimeter. The original mean vertical displacements and the corresponding standard deviations were 4.24 +/- 2.53 mm and 3.86 +/- 2.72 mm, respectively, for the right and left sides. Because a significant negative correlation was observed between original condylar displacements and age factors, the displacement values were statistically adjusted to 2.74 +/- 2.00 mm and 2.44 +/- 1.93 mm. On the horizontal plane, the mean displacements measured were -0.72 +/- 1.53 mm on the right side and -0.51 +/- 1.98 mm on the left. The mean displacement on the transversal plane was 0.03 +/- 0.87 mm. A comparison between these values and those observed in non-deprogrammed groups, as well as those published in the related literature, indicates that use of occlusal splints results in greater mean condylar displacement values, especially vertically, between CR and MHI positions, which contributed to a more accurate orthodontic diagnosis.

Comparison of unilateral chewing movements vs. dental guidance through the dental guidance ratio

STATEMENT OF PROBLEM

Limited knowledge exists about the interaction between dental morphology and mandibular excursive movements.

PURPOSE

This study evaluated dental guidance in lateral excursive movement and its relationship to jaw motion in unilateral chewing.

MATERIAL AND METHODS

Three-dimensional mandibular movement paths (in lateral guiding movements and in the final part of a monolateral chewing stroke) were collected with automated infrared motion analysis in 22 subjects with complete, permanent dentitions. On 2 traces selected from the recorded movements, the angular values projected in all planes of space obtained from 2 lines tangent to a point at a distance of 2.5 mm from maximum intercuspation were used to calculate a canine and a molar dental guidance ratio (DGR). Descriptive statistics were computed for the DGRs in the 3 spatial planes.

RESULTS

Assuming masticatory movements of any given subject are restricted or guided by dental anatomy, a value below 100% of the DGR was expected. This was true for the frontal plane only, with mean values of approximately 80% (working-side movements, canines, and molars) and approximately 60% (nonworking-side movements for both molars and canines). In the horizontal and sagittal planes, mean values between 102% and 137% were found.

CONCLUSION

Within the limitations of this study, masticatory movement was within the physical borders dictated by dental anatomy in the frontal plane only.