This study investigated the immediate effect of changing mandibular position on the electromyographic (EMG) activity of the masseter (MS), temporalis (TM), sternocleidomastoid (SCM) and trapezius (TR) muscles. Thirty-three (33) asymptomatic subjects (16 males and 17 females), ages 23 to 52 were selected. Surface EMG recordings were obtained for all muscles bilaterally with the mandible in a relaxed open position (relaxed) and during maximal voluntary clenching (fullbite) for the following: a non-repositioning appliance (NONREPOS) and repositioning appliance (REPOS). REPOS significantly reduced EMG activity of all muscles bilaterally during fullbite. During relaxation, reduction in EMG activity was only found for TR bilaterally. NONREPOS decreased the EMG activity bilaterally for TM and TR and unilaterally (left) for MS and SCM during fullbite. During relaxation, NONREPOS decreased muscle activity bilaterally for TR and SCM. A unilateral reduction was found for TM (right). These findings suggest that immediate alterations in mandibular position affect the cranio-cervical system. Both mandibular positions tested lowered the EMG activity of masticatory and cervical muscles in the relaxed and fullbite positions. The trapezius muscle was the most responsive to alterations in mandibular position.
This randomized, double-blind study was designed to evaluate the effectiveness of the topical cream Theraflex-TMJ (NaBob/Rx, San Mateo, CA) in patients with masseter muscle pain and temporomandibular joint (TMJ) pain. Fifty-two subjects (5 males and 47 females) were instructed to apply a cream over the afflicted masseter muscle(s) or over the jaw joint(s) twice daily for two weeks. Theraflex-TMJ cream was used by the experimental group, while a placebo cream was used by the control group. The means of pain ratings were calculated prior to the application of the cream (baseline), after ten days of tx (period 1), and 15 days of tx (period 2) days of treatment and five days after stopping the treatment (follow-up). There was a significant decrease in reported pain levels from baseline in the experimental group for period 1 (p < 0.01), period 2 (p < 0.001), and follow-up (p < 0.01). For the control group, no significant differences were found between the different time periods (p > 0.05). There was evidence of minor side effects such as skin irritation and/or burning on the site of the application in two subjects in the experimental as well as two subjects in the control groups. The data strongly suggest that Theraflex-TMJ topical cream is safe and effective for reducing pain in the masseter muscle and the temporomandibular joint.
To evaluate the effect of cigarette smoking (CS) on pain intensity in a sample of temporomandibular disorder (TMD) patients, 352 clinical charts were reviewed. Subjects were first divided into two groups: smokers (YS) and nonsmokers (NS); then, YS were further divided into three subgroups: light smokers (LS), moderate smokers (MS), and heavy smokers (HS). Overall TMD pain intensity was higher in YS, compared to NS, and a correlation was found between pain intensity and the number of cigarettes smoked in a day by each subject. A significant difference was evident between NS and HS. The results were not evident in males; age was not correlated either with smoking or pain intensity, and the effect of CS on pain intensity was not correlated with any particular TMD diagnosis. CS seems to be a relevant factor affecting the intensity of TMD pain, thus, control of smoking habits should be considered when treating TMD patients.
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