Biomechanical properties of masseter muscle assessed through myotonometry in patients with temporomandibular disorder treated with ultrasound therapy: a randomized comparative study.

BACKGROUND

The aim of the study was to make an objective quantitative assessment of effectiveness of procedures with the use of a therapeutic dose of ultrasounds in this nosological entity, in connection with improved biomechanical properties and alleviation of pain experienced in masseter muscles.

METHODS

The study included 40 patients with temporomandibular disorder. In group 1 (N.=20) ultrasound therapy (1.2 W/cm2) was carried out, while in group 2 (N.=20) sham therapy was applied. A total of 10 procedures were performed. Myotonometric measurements and assessment of pain intensity were carried out before treatment and after the completion of procedures.

RESULTS

The analysis revealed a significant difference (P=0.011) between the values of decrement (D) measured on day 0 (2.08±0.45 [log]) and day 4 (1.80±0.55 [log]) in group 1. In group 2 no statistically significant differences were noted between the results obtained on consecutive days of the therapeutic cycle. A statistically significant difference in values of decrement (D) between group 1 (1.80±0.55 [log]) and group 2 (2.23±0.51 [log]) was noted on day 4 of the experiment (P=0.021). Both in group 1 and in group 2, a statistically significant reduction of pain intensity (VAS Scale) was obtained.

CONCLUSIONS

The masseter muscle was more elastic during ultrasound therapy. However, the effect was transient. The analgesic effect was also observed in the control group; therefore, a placebo effect cannot be excluded.