Materials and method. This randomized controlled clinical trial was conducted between January 2016 and June 2016 at the Andres Bello University Dental Clinic (Viña del Mar, Chile). Study subjects were recruited from the universe of patients seeking treatment for jaw pain at the School of Dentistry. All subjects were informed about the study by their operator and gave their written consent before beginning the study. The protocol, design, and implementation were approved by the Scientific Ethics Committee of the Faculty of Dentistry of the Andres Bello University, Viña del Mar, Chile (Folio No. 056, year 2016). Which was in accordance with the latest version of the Declaration of Helsinki of the World Medical Association (Declaration of the World Medical Association of Helsinki, 2013).
Sample's size calculation. An error percentage of 7% was calculated according to a confidence level of 91%, considering a prevalence of chewing muscle pain of 9% and an expected loss of 1.08% based on the losses obtained in the study carried out by Kalamir. et al. in 2012 (Kalamir et al., 2012). The minimum number of participants required for each group was 25 patients (50 patients in total).
Randomization and interventions. After meeting the inclusion and exclusion criteria, subjects were randomly assigned to two groups using a computer generated sequence "random list" developed by random.org.
Evaluation methods. The initial evaluation, to determine the degree of involvement of axis I, was carried out following the symptom questionnaire and clinical examination guidelines according to the DC/TMD protocol. Additionally, the questionnaire for the chronic pain grade scale (GCPS v2.0) and the functional limitation scale (JFLS-20) of axis II of the DC/TMD protocol were applied. In turn, an intraoral clinical examination was performed to rule out pain of dental origin.
Statistic analysis. Demographic characteristics of the sample were reported descriptively. Data were analyzed using Wilcoxon signed-rank test for comparisons between periods (initial evaluation, and weeks 2, 6, and 10) and Wilcoxon rank-sum test for comparison between groups of the variables MMP, MRM, JFLS-20. Qualitative evaluation of adherence to self-management was analyzed using Fisher exact test. Qualitative evaluation of adherence to home exercises was descriptively reported. The level of significance was established at p=0.05. All statistical analysis was performed using R-Crain 3.01 software.
