The impact of gender of the examiner on orofacial pain perception and pain reporting among healthy volunteers

Mechanisms Underlying Sex Differences in Temporomandibular Disorders and Their Comorbidity with Migraine

Sexual dimorphism in temporomandibular disorders (TMDs) and their comorbidity with migraine are important phenomena observed in clinics. TMDs are the most prevalent orofacial pain conditions with jaw joint and masseter muscle dysfunction. Migraine is the predominant headache commonly associated with TMDs. Women much more often suffer from this orofacial pain than men. However, currently, there is no gender-specific therapy for such pain conditions. Understanding the pathophysiological mechanisms behind sex differences in TMDs as well as their comorbidity with migraines is essential for developing novel approaches for gender-specific treatment of TMDs and related orofacial pain comorbidity. In this review, we summarize recent research progress regarding sex differences in TMDs, focusing on the underlying mechanisms including craniofacial anatomy, hormonal regulation, and roles of opioids, transient receptor potential channels, and endocannabinoid systems. We also discuss the mechanisms of comorbid TMDs and migraine. The information covered in this review will provide mechanistic insights into sex differences in TMDs and their comorbidity with migraine, which could aid in developing effective treatment strategies for the overlapping orofacial pain condition.

Sex as a Biological Variable in Oral Diseases: Evidence and Future Prospects

The interest of the scientific community on sex and gender differences in health and disease has increased substantially over the past 25 to 30 y as a result of a long process of events and policies in the biomedical field. This is crucial as compelling evidence from human and animal model studies has demonstrated that sex and gender influence health, molecular and cellular processes, and response and predisposition to disease. The present scoping review aims to provide a synthesis of sex differences in oral diseases, ranging from periodontal disease to orofacial pain conditions, from risk of caries development to apical periodontitis. Overall, findings from this review further support a role for sexual dimorphism influencing disease predisposition and/or progression in oral diseases. Of note, this review also highlights the lack of consideration of additional factors such as gender and other psychosocial and external factors potentially influencing oral health and disease. New conceptual frameworks capable of capturing multiple fundamental domains and measurements should be developed in clinical and preclinical studies to inform sex-based individualized preventive and treatment strategies.

No effect of social interaction on experimental pain sensitivity: a randomized experimental study

ABSTRACT

Quantitative sensory testing (QST) is a commonly applied paradigm to investigate pain, which is a subjective experience influenced by a myriad of social and contextual factors. Therefore, it is important to consider the potential sensitivity of QST to the test setting and the social interaction that naturally is a part of it. This may particularly be the case in clinical settings where patients have something at stake. Therefore, we investigated differences in pain responses using QST in different test setups with varying degrees of human interaction. In a parallel three-armed randomized experimental study, we included 92 participants with low back pain and 87 healthy volunteers allocated to 1 of the 3 QST setups: 1 setup with manual tests performed by a human tester, 1 setup with automated tests performed by a robot and orally guided by a human tester, and 1 setup with automated tests performed solely by a robot without social interaction with a human tester. All 3 setups consisted of the same pain tests in the same order, including pressure pain threshold and cold pressor tests. We found no statistically significant differences between setups on the primary outcome of conditioned pain modulation nor any secondary QST outcomes. While this study is not without limitations, the results indicate that QST procedures are robust enough not to be influenced by social interaction to an appreciable degree.

No Gender Differences in Pain Perception and Medication after Lumbar Spine Sequestrectomy—A Reanalysis of a Randomized Controlled Clinical Trial

Background: Gender issues have received increasing attention in clinical research of the past years, and biological sex has been introduced as a moderating variable in experimental pain perception. However, in clinical studies of acute pain and gender, there are conflicting results. In particular, there are limited data on the impact of gender differences after spinal sequestrectomy. The aim of this work is to examine gender differences in postoperative pain and pain medication consumption in an inpatient clinical setting. Methods: Data of a completed double-blind RCT was subdivided by gender and reanalyzed by means of an analysis of variance in repeated measures. Outcomes included pain severity measured on a VAS, affective (SES-A) and sensory pain perception (SES-S) and morphine equivalent doses (MED) of analgesics after spinal sequestrectomy. Results: In total, 42 female (47.73%) and 46 male (52.27%) patients were analyzed. No differences in pain severity (VAS: Gender × Time F = 0.35; (df = 2, 86); p = 0.708), affective and sensory pain perception (SES-A: Gender × Time F = 0.08; (df = 2, 86); p = 0.919; SES-S: Gender × Time F = 0.06; (df = 2, 86); p = 0.939) or post-operative opioid use between men and women (MEDs: Gender × Time F = 1.44; (df = 2, 86); p = 0.227) could be observed. Conclusions: This reanalysis of an RCT with respect to gender differences is to our knowledge the first attempt to investigate the role of gender in pain perception and medication after lumbar spine sequestrectomy. In contrast to other studies, we were not able to show significant differences between male and female patients in all pain-related outcomes. Apart from well-established pain management, psychological reasons such as gender-specific response biases or the observer effect might explain our results. Trial registration: The study was registered as a regulatory phase IV study at the German Clinical Trials Register (DRKS), an open-access online register for clinical trials conducted in Germany (Reg-No: DRKS00007913).