Myomonitor Efficacy - An Electromyographic Study with Myofacial Pain Dysfunction

Pantaleo, T.,M.D., Prayer-Galletti, F. M.D., Ph.D., Pini-Prato, g., M.D., and Prayer-Galletti, S.,M.D. "An electromyographic study in patients with myofacial pain-Dysfunction syndrome." Bull. Group. int. Rech.sc Stomat. et Odont. Vol. 26, pp. 167-179, 1983.

Recently dental research has turned to neuro-muscular system: many dental procedures, in order to be entirely successful, require that the masticatory muscles are relaxed and perfectly balanced.  The use of the transcutaneous electrical nerve stimulation (TENS) has been introduced, obtrained with adquate stimulators, such as the Myo-moniotr (Myo-tronics) (Jankelson 1975, Jankelson 1978, Wessberg, 1981): TENS has been able to relieve pain and eliminate the sustained muscle tension of the masticatory muscles of patients with myofacial pain-dysfunction (MPD) syndrome (laskin 1969), combined with occlusal malrelation, which may be the primary cause of MPD syndrome (Lindblom 1953, Alling 1977).

Summary:
An electromypgraphic (EMG) study of ipsilateral masseter and temporalis muscles was undertaken in healthy volunteers and in patients with MPD syndrome, with the aim of getting further insight into the pathophysiology of this disease.  Unlike controls, patients had abnormal MKG features and displayed involuntary sustained EMG activity at rest, chiefly in the temporalis muscles.

Transcutaneous electrical nerve stimulation (TENS) performed with the Myo-monitor induced relaxatio and relief of pain: these effects were however revesred by voluntary mouth closures.

The correction of occlusal position by acrylic splints was able to induce  persistant reduction or a suppression of the abnormal EMG activity at rest and a good relief of pain: moreover, after the corretion, higher levels of EMG activity were found during maximal  biting in the intercuspal position.

Mechanisms underlying these effects were discussed and in particular it was suggested that abnormal afferenct activity from periodontium and jaw muscles may contribute to the establishment of sustained contraction leading to muscular pain, which in turn may cause reflex muscle activity i vicious circles.