Journal of Oral & Facial Pain and Headache, 03/2021

Aims: To assess the efficacy of nonpharmacologic treatments for burning mouth syndrome (BMS). Methods: PubMed, Scopus, Web of Science, and the Cochrane Central Register of Controlled Trials were systematically searched. Reference lists from the latest systematic reviews (2015 to 2020) on BMS treatment in the PubMed, Scopus, Web of Science, and Cochrane Library databases were also scrutinized. Randomized controlled trials (RCTs) or clinical controlled trials (CCTs) in English were considered eligible. Trials on photobiomodulation were excluded to avoid redundancy with recent publications. Risk of bias was established through the Cochrane Risk of Bias tool for RCTs and the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) tool for CCTs. Results: This review included 27 RCTs and 6 open clinical trials (OCTs) describing 14 different nonpharmacologic interventions. Eleven trials experimented with 600 to 800 mg/day of alpha-lipoic acid for 30 to 120 days, with 7 placebo-controlled studies showing significant pain relief. Four trials tested topical and systemic capsaicin for 7 to 30 days, with 2 placebo-controlled studies revealing significant efficacy. Four of the 5 trials testing acupuncture offered favorable evidence of pain relief. Two trials reported significant pain relief after a 2- to 3-month regimen with tongue protectors and showed no difference after aloe vera addition. Short-term pain relief was reported in anecdotal placebo-controlled trials deploying tocopherol, catuama, ultramicronized palmitoylethanolamide, group psychotherapy, cognitive therapy, and repetitive transcranial magnetic stimulation of the prefrontal cortex. Most therapies were safe. Conclusion: Evidence was collected from highly biased, short-term, heterogenous studies mainly focused on BMS-related pain, with scarce data on quality of life, psychologic status, dysgeusia, and xerostomia. Long-term effectiveness of nonpharmacologic treatments should be further investigated, with a more rigorous, bias-proof study design. Keywords: alternative medicine, burning mouth syndrome, clinical trials, nonpharmacological, treatment

Aims: To evaluate the efficacy of a gluten-free diet (GFD) as a treatment modality for pain management in women with chronic myofascial pain in masticatory muscles. Methods: In this randomized controlled trial, 39 female subjects were evaluated according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and divided into three groups: a healthy group (n = 14; mean ± SD age = 34.57 ± 9.14 years); a control group (n = 12; age = 31.50 ± 7.38 years); and an experimental group (n = 13; age 30.00 ± 7.64 years). The outcome variables were: pain intensity, mechanical pain threshold (MPT), and pressure pain threshold (PPT). MPT was performed on the masseter muscle, and PPT was performed on both the masseter and anterior temporalis muscles. A nutritionist prescribed a 4-week individualized GFD for the experimental group. The healthy group was analyzed only initially, whereas the control and experimental groups were analyzed again after 4 weeks. Data were subjected to statistical analysis with a significance level of 5% (one-way analysis of variance followed by Bonferroni post hoc, paired t, Wilcoxon signed rank, Kruskal-Wallis/ Dunn, and Pearson chi-square tests). Results: Participants who underwent a GFD showed reduction in pain intensity (P = .006) and an increase in PPT of the masseter (P = .017) and anterior temporalis (P = .033) muscles. The intervention did not influence the MPT of the masseter muscle (P = .26). In contrast, the control group showed no improvement in any parameter evaluated. Conclusion: GFD seemed to reduce pain sensitivity in women with TMD and may be beneficial as an adjunctive therapy for chronic myofascial pain in masticatory muscles; however, further studies in the fields of orofacial pain and nutrition are required. Keywords: diet, diet therapy, facial pain, gluten-free, pain threshold, temporomandibular disorders

Aims: To understand the experiences of patients diagnosed with chronic facial pain (CFP) who attended a specialist facial pain management program (PMP); specifically, to explore how they experienced attending the facial PMP itself and how they felt it impacted their management of CFP. Methods: Qualitative methodology and focus groups were used to gather patients’ views and experiences of attending a facial PMP. Two focus groups were conducted for patients who had all completed the facial PMP. Discussions were recorded and transcribed. Data were then analyzed using thematic analysis to establish key themes relating to participants’ experiences of the facial PMP. Results: Thematic analysis identified three main themes, with numerous subthemes within them. The theme “psychologic change” had subthemes of self-compassion, acceptance, and reflection. The theme “behavioral change” contained subthemes of re-engagement with valued activity, medication, and communication. The theme “structure and process” contained subthemes of concentration, need for one-on-one time with the clinician, meeting others, and not enough time (clinical and nonclinical). Conclusion: Facial PMPs may provide a valuable treatment to support long-term coping and adaptation for patients with CFP. Positive changes to coping include both psychologic and behavioral elements. Further research is necessary to clarify how group-based facial PMPs should be structured and delivered. J Keywords: chronic facial pain, chronic pain, focus groups, pain management, pain management programme, qualitative, thematic analysis

Aims: To conduct a systematic review compiling an update on the pathophysiology of burning mouth syndrome (BMS) by reviewing the theories and studies published in the last 5 years that consider BMS a neuropathic disease. Methods: A literature review was carried out in April 2020 on the PubMed database by using the following MeSH terms: “(burning mouth OR burning mouth syndrome OR burning mouth pain OR sore mouth OR burning tongue OR oral neuropathic pain OR glossodynia OR stomatopyrosis) AND (etiopathogenesis OR etiopathological factors OR etiology).” Results: The research carried out according to the methodology found 19 casecontrol studies (1 of which was in vivo) and 1 RCT. Of the 19 included studies, 8 showed an evidence score of 2–; 8 showed 2+; another 2 showed 2++; and 1 showed 1+. Quality studies on this topic are insufficient and heterogenous. Conclusion: In the pathogenesis of BMS, both peripheral and central neuropathies appear to play a pivotal role. Nevertheless, the balance between them varies from case to case and tends to overlap. BMS does not seem to be a result of direct damage to the somatosensory nervous system, but a dysfunction in it and in the brain network. Keywords: burning mouth syndrome, etiology, neuropathy, pain disorder

Aims: To investigate the role of exercise-induced hypoalgesia (EIH) in the development of neuropathic pain (NP) following infraorbital nerve (ION) injury and to explore possible underlying mechanisms defining the differences between rats with high and low EIH. Methods: EIH was evaluated by measuring the percentage of withdrawal responses to a series of 30 mechanical stimuli applied to the hind paw before and after 180 seconds of exercise on a rotating rod. The rats were assigned to low- and high-EIH groups based on reduction in the percent of withdrawal responses following exercise. NP was induced in high- and low-EIH rats via ION constriction injury. Rats were tested with graded nylon monofilaments to establish the withdrawal threshold. Increasingly stiff monofilaments were applied to the ION territory until there was a clear withdrawal by the rat. This was repeated a total of three times. A decreased withdrawal threshold indicates allodynia. Testing was performed at baseline and at 3, 10, and 17 days following the injury. On day 17 postinjury, IONs were harvested for the assessment of interleukin (IL)-6, IL-1β, and IL-10 levels. Samples from high-EIH and low-EIH surgically naïve rats served as control for the cytokines study. In this second part of the study, the effects of cannabinoid 1 (CB1) and cannabinoid 2 (CB2) antagonists and naltrexone on EIH profiles and on the withdrawal thresholds to mechanical stimulation were measured. EIH and withdrawal thresholds in high- and low-EIH rats were measured before and after administration of antagonists. Results: Low-EIH rats developed significantly more pronounced allodynia in the ION territory following injury compared to high-EIH rats. At 17 days postinjury, ION IL-1β levels were higher in low-EIH rats, and IL-10 levels were higher in high-EIH rats. CB1 antagonist blocked the analgesic effect induced by exercise in high- but not in low-EIH rats. The CB2 antagonist had no significant effect on high- or low- EIH rats. Naltrexone blocked the effects of EIH in both high- and low-EIH rats. Exercise induced a significant analgesic effect in high-EIH but not in low-EIH rats. CB1 or CB2 antagonist administration had no effect on pre-exercise responses to mechanical stimulation, while naltrexone administration resulted in significant allodynia in both low- and high-EIH rats. Conclusion: This study demonstrated substantial differences between rats with high and low EIH. The results suggest that following ION injury, high-EIH rats may have a more prominent or activated endocannabinoids system and that their inflammatory response is moderated, with higher levels of IL-10 and lower levels of IL-1β. Keywords: exercise-induced hypoalgesia, nerve injury, orofacial neuropathic pain, pain modulation, trigeminal

Aims: To assess the speed and accuracy of a checklist user interface for the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Methods: A diagnostic tool formatted as a checklist was developed and compared to an existing diagnostic tool, the DC/TMD diagnsostic decision trees. Both types of tools use the DC/TMD and were tested by dental students, interns, and residents in the USA and Japan for diagnosis of hypothetical patients. The comparisons were done in a randomized, crossover, controlled, double-blinded trial. Results: Overall, subjects using the experimental tool answered 25% more correct diagnoses (P < .001) and missed 27% fewer diagnoses (P < .01). They were also able to finalize their diagnoses faster than those using the control tool, in 16% less time (P < .05). The difference in accuracy was more pronounced in complex cases, while the difference in speed was more pronounced in simple cases. Conclusion: This checklist is an alternative user interface for the DC/ TMD. Keywords: DC/TMD, diagnosis, Diagnostic Criteria for Temporomandibular Disorders, temporomandibular disorders, TMD