Effectiveness of photobiomodulation therapy on temporomandibular dysfunction in patients with different skin phototypes: a double-blind randomized controlled trial.

• Grant number: 23/10457-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: April 01, 2025
• End date: March 31, 2027
• Field of knowledge: Health Sciences - Dentistry - Orthodontics
• Principal Investigator: Luciano Bachmann
• Grantee: Carlos Eduardo Girasol
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Background: Although photobiomodulation therapy (PBMT) is extensively investigated, the therapeutic procedures involving light irradiation are not yet fully understood within the scientific community. Among relevant factors, biological individualities, such as melanin concentration, emerge as significant confounders. Consequently, different responses can be observed even in health conditions where light intervention has strong biological plausibility or previously reported positive outcomes. Objective: To analyze the effectiveness of PBMT in reducing pain and modulating biochemical markers in women of different skin phototypes with temporomandibular dysfunction. Method: This is a double-blind, randomized clinical trial. A total of 124 participants will be recruited and divided into four groups based on skin phototypes: Fitzpatrick I and II, Fitzpatrick III and IV, Fitzpatrick V and VI, and Sham. Participants will include women aged between 18 and 55 years, reporting facial pain lasting at least three months, and diagnosed with myofascial pain. Evaluations will occur continuously between sessions. Initially, participants will be interviewed and undergo a physical examination, including skin phototype classification, pain intensity and sensitivity measurement, and completion of pain questionnaires. Additionally, saliva will be collected for biochemical measurements. There will be four in-person sessions for evaluation and intervention, plus one remote session for pain intensity assessment (follow-up). Statistical analysis will encompass descriptive aspects, data normality will be assessed using the Shapiro-Wilk test, and interaction between groups will be evaluated by two-way ANOVA with an appropriate correction test. The p-value will be set at 0.05.