Deep and Superficial Masseter Muscle Blood Flow in Women

Purpose: Although changes in blood perfusion have been described as being associated with temporomandibular disorder (TMD) myofascial pain, very little is known about blood flow levels in the deep and superficial masseter muscle. This study investigated blood flow in deep and superficial sites of six healthy female particpants at baseline and during intermittent and continuous biting exercises and recovery. Materials and Methods: Blood flow was monitored unilaterally using a single-fiber probe laser Doppler flowmeter. The blood flow was continuously monitored at baseline and during two biting exercises: (a) intermittent at 25%, 50%, and 100% maximum voluntary bite force for 30 seconds each followed by 90 seconds rest between each biting level and (b) continuous biting at similar maximum voluntary bite force levels followed by 90 seconds rest. Results: There was significantly higher blood flow in the deep sites compared to the superficial sites (p < 0.001) and a significant increase in blood flow during biting compared to baseline (p < 0.001). There were no significant changes in blood flow among the three levels of biting, between the intermittent and continuous exercises, or from baseline blood flow compared to recovery. Conclusions: This study showed regional differences in masseter muscle blood flow, perhaps related to differences in muscle fiber type and pattern of muscle fiber recruitment.