Behavioral Therapy and Self-care vs Thermoformed Occlusal Splints in the Treatment of Masticatory Muscles Pain: a Controlled Clinical Trial.

Materials and method This randomized controlled clinical trial was conducted between October 2017 and January 2018 at the Dental Clinic of the Andrés Bello University (Viña del Mar, Chile). The 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 starting the study. The protocol, design and implementation were approved by the Scientific Ethics Committee of the Faculty of Dentistry of the Andrés Bello University, Viña del Mar, Chile (Folio No. 033, October 2017). Which was in accordance with the latest version of the Declaration of Helsinki of the World Medical Association (World Medical Association Declaration of Helsinki, 2013).

Sample Size Calculation It was calculated according to a confidence level of 95% and a statistical power of 80%. Based on a previous study by Niemelä et al. (Niemelä et al., 2012) it was determined that the variance of the main variable (masticatory muscle pain) of the reference group is 2.6. In turn, the pain variable was measured on the visual analog scale (VAS), where a minimum clinically relevant difference was considered if a 3.5 point decrease was achieved on the VAS scale with respect to treatment, a reference that was also considered in this study.

Randomization and interventions. After meeting the inclusion and exclusion criteria, the subjects were randomly assigned to four groups through a computationally generated sequence "list randomizer" 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 degree 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 exclude pain of dental origin. No subject was excluded for odontogenic pain.

Statistic analysis The demographic characteristics of the sample were reported descriptively. The data studied were tested to determine normality by using the Shapiro-Wilk and Doornik-Hansen tests, data that were parametric, so they were analyzed with a mixed ANOVA test, a factorial part and a repeated means part for the variables degree of chronic pain, masticatory muscle pain, mandibular range of motion, functional limitation and occlusal discomfort. The level of significance used was established at p 0.05. All statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) version 17 software (IBM, Chicago, USA).