Immediate and short-term effect of manual therapy on masseter muscle: an ultrasonography study

Manual therapy is one of the recommended treatments for temporomandibular joint dysfunction (TMD). This study aims to investigate the ultrasonographic changes in the masseter muscle following manual therapy in patients with TMD, as well as the immediate and short-term effects of the therapy on mouth opening, muscle pain, muscle relaxation, and activities of daily living.

The study involved 20 individuals (10 female, mean age = 29.3 ± 11.38; 10 male, mean age = 30.8 ± 10.42) with masseter region pain and TMD, who received a session manual therapy. Ultrasonography assessed changes in the masseter muscle's thickness, echogenicity, and elasticity before therapy, immediately after, and 1-week following therapy. Muscle pain, its impact on daily life, and muscle relaxation were measured using the Visual Analog Scale, and maximum mouth opening was recorded using a caliper. Data were statistically analyzed using the repeated measures ANOVA test, the Friedman, the paired t test.

The study found significant decreases in masseter muscle thickness immediately and 1 week following therapy (p < 0.001), along with a significant increase in elasticity (p < 0.01). Pain levels decreased significantly following therapy (p < 0.001), and the impact of pain on daily activities improved significantly 1 week following therapy (p < 0.001). Muscle relaxation also increased 1 week following therapy compared to immediately following therapy (p < 0.01). Maximum mouth opening was significantly greater immediately following therapy compared to before therapy (p < 0.01).

This study shows that manual therapy results in immediate and short-term improvements in masseter muscle thickness, elasticity, pain reduction, and the impact on daily activities in TMD patients experiencing masseter muscle pain.