Role of photobiomodulation application frequency in facial rejuvenation: randomized, sham-controlled, double-blind, clinical trial.

The present study investigated the effects of different photobiomodulation application frequencies on facial rejuvenation. Ninety-five women 45 to 60 years of age participated in the study. A red LED mask (660 ± 10 nm, 6.4 mW/cm², 8.05 J/cm², 5.02 mW, 21 min) was used, with the analysis of two different time intervals between applications. Group 1 received three weekly applications and Group 2 received two weekly applications for four weeks (total: 12 and eight sessions, respectively). The control group received sham photobiomodulation twice per week for four weeks. The participants were unaware of the allocation to the different groups. Three standardized photographs were taken before and after treatments for assessment using the Wrinkle Assessment Scale (WAS) by three specialists blinded to the allocation and period of the photograph. The Image J software was used by a researcher blinded to allocation and period of the photograph to measure wrinkles in the forehead, glabellar as well as right and left periorbital regions. Patient satisfaction was determined using the FACE-Q questionnaire. The data were analyzed statistically with the significance level set at 5% (p < 0.05). No significant differences among the groups were found with regards to the WAS. In the ImageJ assessment, significant reductions were found in the length of the glabellar and right periorbital wrinkles in the groups treated with photobiomodulation compared to the control group (p < 0.001). Participant satisfaction rates using FACE-Q were 79.6% and 73.4% in Groups 1 and 2, respectively, with significant differences in comparison to the control group (p = 0.001 and p = 0.034, respectively). The quantity of PBM sessions did not significantly alter the positive results achieved in terms of the satisfaction of the participants with their facial esthetics or the photographic assessments performed 30 days after treatment. Thus, two weekly sessions seem to be sufficient for improving patient satisfaction.