Placebo and nocebo response magnitude on temporomandibular disorder‐related pain: A systematic review and meta‐analysis

Abstract

Objectives The aim of this systematic review (SR) was to answer the following question: “In adult patients with temporomandibular disorder (TMD)‐related pain, what is the placebo or nocebo effect of different therapies?” Methods A SR was performed with randomised clinical placebo‐controlled trials on diagnosed painful TMD studies from five main databases and from three grey literature. Studies included must have sample older than 18 years, with painful TMD, which diagnosis was done by Research Diagnostic Criteria (RDC/TMD) or Diagnostic Criteria (DC/TMD). Results Out of 770 articles obtained, 42 met the inclusion criteria for qualitative and 26 for quantitative analysis. Meta‐analysis indicated mean variation on pain intensity for placebo therapy was higher on laser acupuncture with 45.5 mm point reduction, followed by avocado soya bean extract with 36 mm and amitriptyline 25 mg with 25.2 mm. Laser showed a 29% of placebo effect, as well medicine with 19% and other therapies with 26%. Possible nocebo effect of 8% pain increase was found for intra‐articular injection of Ultracain. Conclusions Based on the available data, the placebo response could play a major effect on TMD pain management and may be responsible from 10% to 75% of pain relief. Laser acupuncture, avocado soya bean and amitriptyline promoted the higher placebo effect. Possible nocebo effect was found only for Ultracain injection with 8%. Clinical Relevance Clinicians could apply such evidence to optimise pain management and judgement about treatment efficacy, and researches may find it useful when designing their investigations.

Acupuncture for pain, mandibular function and oral health‐related quality of life in patients with masticatory myofascial pain: A randomised controlled trial

“…Moreover, the absence of a significant difference between groups leads to the assumption that non‐specific factors may have influenced treatment outcomes. Among these, the placebo effect has been considered very important, mainly in acupuncture clinical trials because of individual psychosocial factors that modify biochemistry and neural circuits 45,46 . Hence, the placebo effect as well as other unspecific factors such as natural history and regression to the mean could not be ruled out in this study.…”

Comparison of low‐level laser therapy and standard treatment for temporomandibular disorders: An assessment of therapeutic and placebo effects

“…On the other hand, just like drug treatments, any other therapeutic intervention will also have some degree of placebo effect, and LLLT is no exception to this rule. 28,30,31,38 Porporatti et al conducted a systematic review and meta-analysis to investigate the magnitude of placebo and nocebo effects on temporomandibular disorder (TMD)-related pain. 28 The In this study, one group was treated with low-power laser, and the placebo group was exposed to inactive low-power laser (without radiant energy).…”

“…It has a placebo effect on patients, like any other treatment. [28][29][30][31] The recent studies on LLLT for TMD provide mixed evidence for its effectiveness, highlighting the need for further research to clarify its potential benefits and optimal treatment parameters. Therefore, the question remains whether the placebo effect of LLLT justifies its use as an adjuvant treatment and imposing more cost on the patient.…”

Polyphenols as Potential Agents in the Management of Temporomandibular Disorders

“…In this regard, it has been observed by numerous studies that psychological factors including stress, anxiety, and tension are closely related to the onset of headache, orofacial and TMJ-related pain, resulting in the chronic pain of TMJ which leads to distress, depression, and somatization [124]. One of the key questions regards the impact of chronic orofacial pain of TMJ on the quality of life of subjects, making psychic support crucial, including placebo therapies that can improve TMD pain management and may be responsible for 10-75% of pain relief [125] and also counseling approach [121]. The term counseling is used for a series of practices relating to the psychological sphere and properly means to "come to help", "to support", since TMJ-pain leads to a biopsychosocial limitation [121].…”