One possible cause of the reported positive treatment effect by low-power
laser exposure in
muscle pain conditions could be that it increases the local microcirculation. The aim of this study was therefore to investigate the immediate effects on masseter muscle blood flow by low-power
laser exposure in patients with chronic
orofacial pain of muscular origin in comparison to healthy individuals. Twelve patients with myofascial
pain of orofacial muscles and 12 age and gender matched healthy individuals participated in the study. Before
laser exposure the subjects were examined clinically and the patients scored their current
pain intensity from the most tender masseter muscle. Intramuscular
laser-Doppler flowmetry was performed unilaterally in the most tender point (patients) or in a standardized point (healthy subjects) of the masseter muscle. The muscle was first exposed with a
Gallium-
Aluminum-Arsenide
laser (active
laser) or placebo
laser for 2 min in a randomized and double-blind manner. After another 8 min the muscle was treated with the other
laser for 2 min and the LDF recording continued for 8 min. Finally, the patients again assessed the
pain intensity. Data were analyzed blindly by one of the authors not participating in data collection. The
pain intensity was not affected by
laser exposure. The blood flow did not change significantly in the patients, but increased after active
laser exposure and decreased after placebo exposure in the healthy individuals. The difference between active
laser and placebo was significant. In conclusion, the results of this study do not support an effect of low-power
laser exposure on masseter muscle microcirculation in patients with chronic
orofacial pain of muscular origin.