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Occlusal devices, particularly the stabilization appliances, have been commonly used as treatment for painful temporomandibular disorders (TMDs). However, the mechanisms of action of these devices are still unclear, including the role of the placebo effect in the pain management. The purpose of this network meta-analysis was to identify to what extent the degree of efficacy of stabilization appliances in the management of painful TMDs arises from the placebo effect only or whether it arises chiefly from an actual effect. An electronic search was undertaken to identify randomized clinical trials (RCTs) published up to April 2020, comparing the efficacy of the stabilization appliances in patients with painful temporomandibular disorders, with nonoccluding appliances (active placebo), and untreated controls (passive placebo). Outcome variables were pain intensity at follow-ups, the proportion of participants reporting pain improvement, and the number needed to treat. The quality of evidence was rated as per the Cochrane tool for assessing risk of bias. Mean difference was used to analyze via frequentist network meta-analysis by using the STATA software program. Treatment with stabilization appliances showed a significant reduction in pain intensity when compared with the other groups; but, the lower pain intensity at follow-ups in favor of stabilization appliances when compared with nonoccluding appliances was not statistically significant. However, a significantly higher number of participants reported pain improvement after treatment with stabilization appliances when compared with those treated with nonoccluding appliances or untreated participants. This network meta-analysis showed no significant difference in reported pain intensity at follow-ups between the treatment of painful TMDs with stabilization appliances or nonoccluding appliances (active placebo). However, a significant difference in participants reporting treatment satisfaction with reduced pain, and a significantly lower number needed to treat in favor of stabilization appliances were found. Patient-reported treatment satisfaction probably included more domains than just pain intensity, such as improvements in physical functioning and psychosocial factors, and deserves further investigation. The authors concluded that stabilization appliances treatment efficacy is beyond the placebo effect. [ABSTRACT FROM AUTHOR]

Abstract: This study aimed to investigate whether granisetron reduces masseter muscle pain and allodynia induced by hypertonic saline. Fifteen healthy women and 15 age-matched healthy men participated in this randomized, placebo-controlled, double-blinded study. They first received bilateral injections of hypertonic saline into the masseter muscles (internal control). The evoked pain intensity and the pressure-pain threshold (PPT) were recorded during 30 minutes. Granisetron was then injected on one side and placebo (normal saline) on the contralateral side. Two minutes thereafter, the hypertonic saline injections were repeated. Pain and PPT were again recorded. The first injection of hypertonic saline induced pain of similar intensity, duration, and pain area on both sides, but with larger pain area in the women (P = .017). The PPT did not change significantly. The second injection of hypertonic saline induced considerably less pain (62.5%), of shorter duration (44.1%), and of smaller area (77.4%) on the side pretreated with granisetron (P = .005). The PPT was increased on the granisetron side in the men (P = .002). The results of this study show that local injection of a single dose of granisetron attenuates masseter muscle pain induced by hypertonic saline. Perspective: This article presents the changes of hypertonic saline–induced masseter muscle pain characteristics by infusion of granisetron. It appears that the pain-inducing effect in this experimental pain model is partly due to activation of 5-HT3-receptors. Hence, the results indicate that granisetron might offer a new treatment approach for localized myofascial pain. [Copyright &y& Elsevier]