INFLUENCE OF FATIGUE IN THE ABILITY TO CONTROL THE MUSCULAR EFFORT TRAJECTORY IN PATIENTS WITH TEMPOROMANDIBULAR DISORDERS

Objectives:
The measure of the patient’s ability to control the muscular force trajectory through real-time visual biofeedback was found, in our preliminary study, to have promising diagnosis potential for temporomandibular disorders (TMD), with high specificity (94%) but low sensitivity (60%). In the present study we hypothesized that the sensitivity of this measure can be improved by increasing the number of experimental repetitions of the measure. We tested this hypothesis in patients with TMD.
Methods: Ten TMD patients were included in the study (mean age 45 years). A standardized automatic and computerized experimental setting that allowed the individual to control the muscular force trajectory through real-time visual biofeedback was used. Twelve setting repetitions were performed in each individual and the required time to control the trajectory was measured for each setting. The sequence was divided into two groups (setting 1-6 and setting 7-12) in order to detect any differences. Standard deviation and coefficient of variation of these measurements were calculated. Non-parametric tests were used to compare between groups.
Results: All patients were able to complete the twelve experimental settings and effectively control the muscular force trajectory. No statistical differences were found between groups regarding coefficient of variation and standard deviations. The mean time for the first group of repetitions was 6.54 seconds and for the second group was 5.36 seconds.
Conclusions: The experimental setting of twelve repetitions/measures did not show differences if compared to six repetitions/measures. It is possible that more repetitions are needed in order to provoke muscular fatigue and influence the outcome. A future study using more repetitions in a bigger sample size should explore this hypothesis.

ACKNOWLEDGEMNTS
The study was supported by the Comisión Sectorial de Investigación Científica (CSIC), Espacio Interdisciplinario and the School of Dentistry, Universidad de la República, Montevideo, Uruguay.