Increasing gender differences in the prevalence and chronification of orofacial pain in the population

Synthesis and evaluation of isoquinolinyl and pyridinyl-based dual inhibitors of fatty acid amide hydrolase and soluble epoxide hydrolase to alleviate orofacial hyperalgesia in the rat

The treatment of orofacial pain disorders is poor. Both opioids and serotonin agonists are commonly used; however, they produce dangerous and unpleasant side effects. Therefore, there is an urgent need to identify new pharmacological treatments that can resolve orofacial pain. Moreover, a treatment that engages multiple mechanisms using one compound may be advantageous. Fatty acid amide hydrolase (FAAH) and soluble epoxide hydrolase (sEH) are two enzymes that can regulate both pain and inflammation via independent pathways. Small molecules that inhibit both enzymes simultaneously were previously synthesized and produced antinociception in vivo. Quinolinyl-based dual inhibitors of FAAH and sEH can inhibit acute inflammatory pain in rats. Here, following on these findings, we generated 7 new isoquinolinyl- and 7 pyridinyl-based analogs and tested their inhibition at both enzymes. Structure-activity relationship study coupled with docking experiments, revealed that the isoquinoline moiety is well-tolerated in the binding pockets of both enzymes, yielding several analogs with nanomolar activity in enzymatic assays. All newly synthesized analogs were assessed in the solubility assay at pH 7.4, and we determined that isoquinolinyl- and substituted pyridinyl-analogs exhibit limited solubility under the experimental conditions. The most potent inhibitor, 4f, with IC50 values in the low nanomolar range for both enzymes, was evaluated in a plasma stability assay in human and rat plasma where it showed a moderate stability. Primary binding assays revealed that 4f does not engage any opioid or serotonin receptors. A high dose (3 mg/kg) of 4f reversed orofacial hyperalgesia following pretreatment with nitroglycerin and orofacial injection of formalin; however, this same dose did not inhibit acute orofacial inflammatory pain or restore pain-depressed wheel running. These findings indicate that simultaneous inhibition of FAAH and sEH using isoquinolinyl-based dual inhibitors may only reverse certain components of orofacial hyperalgesia.

Prevalence of Painful Temporomandibular Disorders and Overlapping Primary Headaches Among Young Adults

BACKGROUND

Large population-based estimates of the prevalence of painful temporomandibular disorders (p-TMD) utilising standardised screening tools are scarce and have not investigated the prevalence of overlapping primary headaches. We aimed to estimate the prevalence of p-TMD in a large population of young adults (18 to 23 years) and to estimate the co-occurrence of p-TMD and two primary headaches, migraine and tension-type headache (TTH). The study also aimed to examine the extent of psychological (PHQ-4) and physical (PHQ-15) comorbidities and report prevalence across three gender categories (women, men and other).

METHODS

Survey data from the Danish National Birth Cohort were collected (n = 11,982), in a cross-sectional observational design. A sensitivity analysis was conducted to address participation bias, revealing minimal impact on the estimates.

RESULTS

The overall prevalence of p-TMD was 26.4% with gender-specific prevalence of women: 31.5%, other: 39.2% and men: 16.8%. Among those with p-TMD, 80.5% reported headaches at least once a month, and 13.8% over 15 days monthly. For the p-TMD individuals with a medical headache diagnosis, 31.9% experienced TTH and 10.9% migraine. The study also identified a higher proportion of moderate/severe psychological distress and physical symptoms in the p-TMD group compared to the non-p-TMD group. Logistic regression revealed a positive association between PHQ-4 and p-TMD, modified by gender (p = 0.016).

CONCLUSIONS

High overall prevalence of p-TMD and overlapping primary headaches was found in young adults. In addition, the study reports gender-specific associations between p-TMD, psychological distress and physical comorbidities indicating that this association is stronger for men than for women.

SIGNIFICANCE STATEMENT

This study found a higher-than-expected prevalence of painful temporomandibular disorders in young adults. It is based on a large population cohort and used standardised and validated screening tools. The study also reported common co-occurrence of primary headaches and explored gender differences. The study raises awareness for a possibly underestimated health burden in young individuals, particularly among individuals experiencing psychological distress and multiple physical symptoms.

Tinnitus in patients with orofacial complaints

BACKGROUND

This study explored subjective tinnitus frequency in patients referred to an interdisciplinary orofacial pain clinic using the "web-based interdisciplinary symptom evaluation" (WISE) tool, which included a wide range of psychometric data. Our goal was to analyze the correlation between orofacial complaints and tinnitus, as well as their association with other psychometric data-an approach that, to our knowledge, has not been undertaken to this extent before.

METHODS

From 2017 to 2020, we analyzed 1369 anonymized patient records using completed WISE. This included diverse questionnaires and symptom-related screener questions. Positive screening responses triggered additional assessments, such as short Tinnitus Handicap Inventory (THI-12) and Patient Health Questionnaire 4 (PHQ-4). Ear symptoms, tinnitus severity and tinnitus frequency were evaluated. Furthermore, Spearman correlations were performed with other questionnaires addressing pain, anxiety, depression, health, stress and insomnia.

RESULTS

Among 1369 patients with orofacial complaints, 69% were female. Notably, 19.7% (269) completed THI-12 due to severe ear symptoms; of these, 62.1% were female. Female mean THI-12 score was significantly lower (p = 0.007) with 9.3 (SD = 7.0) compared to males 11.6 (SD = 6.8). Additionally, there was a significantly different gender distribution between all patients with tinnitus and those with severe tinnitus (p = 0.032), with an increased proportion of men in the latter group. THI-12 positively correlated with all WISE questionnaires, strongest with PHQ-4 (p < 0.01).

CONCLUSIONS

Our study unveils a common co-occurrence of orofacial and ear complaints, particularly tinnitus. The practical implication of the observed gender differences suggests that in male patients presenting with orofacial pain, tinnitus and its associated distress should be actively addressed to initiate a multidisciplinary treatment approach.

CLINICAL TRIAL NUMBER

Not applicable. Since this study was a retrospective analysis of anonymized data, trial registration was not necessary.

TRPV1-target drugs for the treatment of orofacial pain

Orofacial pain, encompassing sensory and emotional discomfort in the facial and oral regions, is a multifaceted condition that significantly impacts patients' quality of life. This review focuses on the role of Transient Receptor Potential Vanilloid 1 (TRPV1) channels in modulating orofacial pain and new ligands targeting this receptor. TRPV1 channels act as key mediators of nociception, responding to stimuli such as temperature, pH changes, and capsaicin molecules. Recent advancements in TRPV1-targeted therapeutics, including natural, synthetic, and protein-based molecules, offer promising strategies for pain management. This review analyzed studies related to TRPV1-mediated pain inhibition, including seven clinical trials and preclinical investigations. The compounds studied in these works demonstrated pain relief, although adverse effects were reported. TRPV1-targeted molecules represent a novel avenue for developing innovative pharmacological interventions, addressing the limitations of current therapies, and improving patient outcomes in managing orofacial pain.

Enhancing orofacial pain relief: α-phellandrene complexed with hydroxypropyl-β-cyclodextrin mitigates orofacial nociception in rodents

Orofacial pain affects 10-15% of adults and can severely impact quality of life. Despite ongoing treatment challenges, monoterpene alpha-phellandrene (PHE) shows potential therapeutic benefits. This study aimed to develop and evaluate an inclusion complex of PHE with hydroxypropyl-beta-cyclodextrin (PHE-HPβCD) for treating orofacial pain. The PHE-HPβCD complex was created using physical mixing and characterized by differential scanning calorimetry (DSC) and high-performance liquid chromatography (HPLC) to determine encapsulation efficiency. The complex exhibited a 70.45% encapsulation efficiency. Male Swiss mice were used in models of orofacial pain induced by formalin, cinnamaldehyde, glutamate, and corneal nociception by hypertonic saline. Additionally, cytokine levels (TNF-α and IL-1β) were measured in the upper lip tissue of mice subjected to the formalin model. Both PHE and PHE-HPβCD showed significant antinociceptive effects at a 50 mg/kg dose during formalin-induced pain, reducing both neurogenic and inflammatory phases of pain. PHE-HPβCD also reduced TNF-α and IL-1β levels. For cinnamaldehyde and glutamate-induced nociception, both treatments reduced pain behavior, but only PHE-HPβCD decreased eye wipes in corneal nociception. These results suggest that PHE, especially in complexed form, alleviates orofacial pain by potentially modulating pain-related receptors (TRPA1 and TRPV1), mediators, like glutamate, and reducing pro-inflammatory cytokines. Further research is needed to explore the precise mechanisms of PHE in chronic orofacial pain models, but the study indicates promising avenues for new pain treatments.

Exploring the Patients' Perspective on Digital Tools for Psychosocial Assessment in Dentistry

BACKGROUND

Psychosocial screening is a valuable part of the assessment of patients with orofacial pain, as psychosocial factors will affect prognosis and treatment outcomes. Paper-based questionnaires are predominately used to assess the degree of psychosocial comorbidity; however, digital alternatives for screening questionnaires may be more cost-effective and resource-saving if patients are receptive to using them.

OBJECTIVE

To evaluate how patients perceive digital psychosocial screening in dentistry.

METHOD

Using a qualitative approach, individual semi-structured interviews were conducted with a purposive sample of adult patients with orofacial pain (n = 16) recruited from specialist dental clinics in Umeå and Gävle, Sweden. The interviews were transcribed verbatim and then analysed using Qualitative Content Analysis. Before the interviews, patients first completed the paper-based questionnaires and then the digital version.

RESULTS

The analysis of patients' experiences resulted in an overarching theme: Patients appreciate a holistic approach, thus valuing psychosocial screening, and they particularly favour screening in a digital format. From this theme, two categories emerged: Perceptions about health shape patients' expectations of dental care, and with deeper understanding of the value of psychosocial assessment, patients appreciate a holistic approach that includes psychosocial factors. Digital screening is perceived by patients as a reliable, meaningful and environmentally sustainable method.

CONCLUSIONS

In general, the patients appreciated a holistic approach in dentistry and understood the value of psychosocial screening as part of this. From the patients' perspective, digital psychosocial screening was both acceptable and beneficial. The findings support the introduction of digital psychosocial screening into daily dental practice.

Nicorandil Repurposing in Orofacial Pain: Preclinical Findings in Adult Zebrafish

This study investigates the orofacial antinociceptive activity of nicorandil in adult zebrafish and explores the involvement of TRP channels in this effect. Nicorandil, a known antianginal drug, reduces nociceptive behaviors induced by capsaicin (TRPV1 agonist), cinnamaldehyde (TRPA1 agonist), and menthol (TRPM8 agonist) without altering the locomotor activity of the zebrafish. Pretreatment with specific TRPA1 and TRPV1 antagonists prevents the antinociceptive effects of nicorandil, indicating its action on these channels. Molecular docking studies support these findings, demonstrating high chemical affinity and specific binding of nicorandil to the TRPV1 and TRPA1 channels, leading to stabilization and reduced biological activity of these channels. In contrast, the antinociceptive effect of nicorandil on menthol-induced nociception is not affected by a TRPM8 antagonist, suggesting that TRPM8 modulation is not involved in nicorandil's mechanism of action. The study highlights the potential of nicorandil as an analgesic through its interaction with TRPV1 and TRPA1 channels, providing a molecular basis for repositioning nicorandil as an effective analgesic drug.

Prevalence of Temporomandibular Disorder Symptoms After Whiplash Trauma-A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Temporomandibular disorders (TMDs) is an umbrella term for pain and dysfunction involving jaw muscles and/or the temporomandibular joint, with whiplash trauma suggested to be one risk factor. The aim was to evaluate prevalence and relative risk of TMDs in the acute and chronic stages after whiplash trauma.

DATABASES AND DATA TREATMENT

This review was registered in Prospero (CRD42023407091) and followed the PRISMA guidelines. A literature search in PubMed, Scopus and Web of Science on 10 March 2023 and updated 29 April 2024 identified studies reporting prevalence of TMD after whiplash trauma. Risk of bias was assessed with Joanna Briggs Institute Prevalence Critical Appraisal Tool. A random effect meta-analysis was performed for prevalence of TMD pain.

RESULTS

After screening of 671 identified studies, 96 articles were assessed in full text. Fourteen studies, with 840 cases in the acute and 8293 cases in the chronic stage (i.e., > 3 months post-trauma) were included in a qualitative analysis together with 1591 controls. Nine studies, including 449 cases in the acute and 7912 individuals in the chronic stage after trauma, together with 515 controls, were included in the meta-analysis. Mean prevalence for TMD pain was 18.9% (95% CI 9.71-29.98) in the acute case group, 26.8% (95% CI 15.07-38.79) in the chronic case group, and 5.7% (95% CI 3.08-8.96) in the control group.

CONCLUSIONS

The higher prevalence of TMD pain already in the early stage after whiplash trauma, emphasises the need for early comprehensive clinical assessment as well as targeted research to understand underlying mechanisms.

SIGNIFICANCE

The prevalence of Temporomandibular disorder pain was high already in the acute stage after whiplash trauma, and there was no evidence of any decrease from the acute to the chronic stage. This finding suggests that early assessment and management rather than a 'wait-and see' approach should be recommended when patients present with orofacial pain related to whiplash trauma.

Jaw muscle and joint psychophysics-relevance for clinical orofacial pain practice and research. A narrative review

Diagnosis of jaw muscle and temporomandibular joint (TMJ) pain has been greatly standardized with the development and implementation of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). A significant part of the DC/TMD examination-pain on palpation and jaw movements-relies on psychophysical principles in the clinical procedures. Thus, it is essential that examiners are aware of the strengths and limitations of such techniques. Here we first review the background and psychophysical techniques used in the clinic and then discuss opportunities to apply both simple and more advanced modifications in research settings to further understand musculoskeletal pain mechanisms and signatures. The goal is to facilitate development of individualized treatment and precision medicine for which a good starting point seems to be careful pain phenotyping where psychophysical testing may play a substantial role.

Comparative analysis of acute and chronic painful temporomandibular disorders: Insights into pain, behavioral, and psychosocial features

OBJECTIVE

The scarcity of literature necessitates further research to differentiate between acute and chronic painful temporomandibular disorders (TMDs). This study compared pain characteristics, oral behaviors, jaw function, and psychosocial distress between TMD patients with acute and chronic pain, examined correlations among variables, and identified factors associated with chronic pain-related TMDs (PT).

METHODS

Anonymized data were gathered from consecutive patients seeking TMD treatment at a university-based oral medicine clinic. Axis I diagnoses were made using the Diagnostic Criteria for TMDs, and patients with PT were categorized into acute (AP) and chronic pain (CP) groups. Axis II assessments were performed, evaluating pain characteristics, oral behaviors, jaw functional limitation, somatic symptoms, depression, and anxiety. Statistical analysis utilized chi-square/non-parametric tests and logistic regression (α =  0.05).

RESULTS

Among the 488 PT patients, 34.6% experienced AP and 65.4% had CP. Significant differences were observed in pain intensity, interference, disability, jaw overuse behavior, functional limitation, somatic symptom burden, depression, and anxiety. (CP>  AP). Moderate-to-strong correlations were found in both the AP (rs =  0.43-0.83) and CP (rs =  0.46-0.87) groups, although the specific relationships between pain, behavioral, and psychosocial factors differed somewhat. The multivariate regression model revealed that only pain intensity (OR =  1.01) and oral behaviors (OR =  1.06) significantly increased the odds of chronic PT.

CONCLUSION

Chronic pain was more prevalent in PT patients and associated with greater severity in pain, behavioral, and psychosocial variables. Pain intensity and oral behaviors were linked to an increased likelihood of chronic pain.

Chronic orofacial pain and pharmacological management-a clinical guide

Orofacial pain is a widespread health concern that significantly hinders an individual's capacity to engage in daily activities. This type of pain can be classified into three main categories: nociceptive pain, neuropathic pain, and nociplastic pain. Each category involves different mechanisms and requires specific treatment approaches. For optimal treatment of orofacial pain disorders, a multidisciplinary pain management approach is essential. This approach should integrate both nonpharmacological and pharmacological modalities to address the diverse underlying causes and manifestations of pain. In this review, we focus on the current evidence and advancements in the pharmacological management of chronic orofacial pain. We explored the effectiveness of different medications, their mechanisms of action, and their role within a comprehensive pain management plan.

Women are worse off in developing and recovering from temporomandibular disorder symptoms

Decision-making for temporomandibular disorders (TMDs) is reported being a clinical challenge, partly due to uncertainities in assessment of long-term prognosis. Therefore, our aim was to explore variations over time in TMD symptoms and possible sex or age differences. In this cohort study, data were prospectively collected 2010-2017 from the general population in Västerbotten, Northern Sweden. Adults were eligible if they had undergone at least two routine dental check-ups that included screening for TMDs (3Q/TMD) from which states were defined as absence or presence of TMD pain and/or jaw catching/locking. The rate of transitions was estimated between TMD states within a time span of one year. A total of 94,769 individuals were included (49.9% women) with 205,684 repeated visits and 9,006 state transitions recorded over the 8-year period. Compared to men, women had higher rates of transitions from no TMDs to any TMD symptoms. Furthermore, women had a lower rate of transition from TMD pain only to no TMDs. The finding of a poorer prognosis in women, as well as previously reported potential gender differences in pain perception and reporting, reinforces that gender differences should be accounted for in the treatment planning stage for patients with onset of TMDs.

Orofacial pain models induce impairment in spatial learning and working memory in rodents: A systematic review and meta-analysis

Orofacial pain is one of the most common causes of chronic pain leading to physical and cognitive disability. Several clinical and pre-clinical studies suggest that chronic pain results in cognitive impairment. However, there is a lack of meta-analyses examining the effects of orofacial pain models on behavioral learning and memory in rodents. Thus, this study aimed to evaluate whether orofacial pain models can impair learning and memory in rodents. The protocol was registered in PROSPERO (CRD42023355502). We used CAMARADES and SYRCLE to estimate the quality and the publication bias by using Egger's and Begg's test. Here, 21 studies were included in this systematic review and meta-analysis. We included 12 studies with trigeminal neuralgia models, 4 with migraine-like pain models, 4 with tooth nociception, and 1 with acute orofacial pain model. Spontaneous nociception and facial mechanical allodynia were observed in orofacial pain models. Regarding spatial learning we detected that latency to find the platform in the Morris water maze (MWM) was increased in orofacial pain models (related to facial mechanical allodynia or spontaneous nociception). Although the mean quality of the articles was high, we identify publication bias in the Begg's test for the time in the quadrant in the MWM. Our findings revealed that spontaneous nociception and facial mechanical allodynia in orofacial pain models contribute to the working memory and spatial learning dysfunction. Therefore, further studies are still needed to evaluate the influence of sex, age, social isolation, and environmental enrichment in orofacial pain-related learning and memory.

Outcome of Screening Questions for Temporomandibular Disorders and Related Treatment in Adult Patients Attending the Public Dental Service

BACKGROUND

Approximately 30% of the adult population experiences symptoms under the concept of temporomandibular disorder (TMD). To identify patients with TMD who may require further evaluation, three screening questions (3Q/TMD) have been introduced.

OBJECTIVES

The aim of this study was to explore the prevalence of self-reported TMD and the amount of treatment received by patients in the Public Dental Service in Stockholm and how many were referred to an orofacial pain specialist.

METHODS

Health declarations from 402 012 patients 18 and older were included. Answers to the 3Q/TMD, gender, performed treatment, and referrals were extracted from the patients' records.

RESULT

The prevalence of affirmative answers to 3Q/TMD was 4.6% and higher in the 20-29 age group compared to the 60-69 group. Affirmative answers in general led to more treatment, and an affirmative answer to Q1 gave the highest probability of treatment (OR 5.13; 4.87, 5.41) with occlusal splint therapy being the most common. Age did not significantly predicting the amount of treatment (p = 0.05), although there was a tendency towards less treatment in older age groups. In total, 0.74% of the study population were referred to an orofacial pain specialist, with a higher probability of referral for those who answered affirmatively (p < 0.001).

CONCLUSION

The prevalence of self-reported TMD among patients in the Public Dental Service aligns with findings from similar studies. Patients who answered affirmatively to one or more of the screening questions were more likely to receive treatment or a referral. The 3Q/TMD effectively identifies patients who may benefit from further evaluation and referral, although the rate of treatment remains low.

Sex and academic stage differences in work-related musculoskeletal disorders pain among dental students. A cross-center cross-sectional study

OBJECTIVE

Dental professionals are highly vulnerable to work-related musculoskeletal disorders (WMSD). As females, who are more prone to WMSD, represent a growing proportion of the dental workforce, this study explored sex differences in WMSD-pain prevalence among dental students, and differentiated it between preclinical and clinical students.

METHODS

A multi-center cross-sectional study was conducted among dental students at three U.S. dental schools. An anonymous survey assessed prevalence of WMSD pain over the last 12 months and 7 days using the Nordic Musculoskeletal questionnaire. Sex and academic stage differences were analyzed with independent t-tests and chi-square, adjusted for demographics and occupational habits (working hours, self-reported ergonomics, loupes, sport engagement) with ANCOVA.

RESULTS

Among 175 students (26.6±3.6 years, 66.9% females), 93.7% and 57.7% reported WMSD-pain in the past 12 months and 7 days, respectively. Females scored higher than males in pain intensity (p=.025), WMSD-pain prevalence in the past 7 days (p=.006), and number of painful body sites in the past 12 months (p=.006) and 7 days (p<.001). Clinical students had higher WMSD-pain prevalence (p<.001) and number of painful body sites (p<.001) in the past 7 days than preclinical students. Differences remained significant only among females.

CONCLUSION

A high prevalence of WMSD-pain was evident in dental students, with significant sex and academic stage differences.

Influence of gender and bruxism on the masseter muscle: A population-based magnetic resonance imaging study

INTRODUCTION

This study aimed to (1) examine the cross-sectional area (CSA) of the masseter muscle in relation to bruxism and (2) investigate if there are gender-related differences in the masseter muscle in a population-based magnetic resonance imaging (MRI) study.

METHODS

The study included 720 subjects aged 30-89 years (391 women and 329 men) from the Study of Health in Pomerania, a cross-sectional population-based study assessing the prevalence and incidence of common population-relevant diseases and their risk factors in Northeastern Germany. The participants underwent both a whole-body MRI and a full oral examination. The CSAs of the masseter muscles on both sides were measured from MRI images. The presence or absence of awake and/or sleep grinding and clenching, unilateral chewing, and other parafunctional activities were obtained from the dental interview. Linear and ordinal logistic regression models were used to examine the associations between the CSAs of the masseter, bruxism, and gender.

RESULTS

The frequency of bruxism and reports of muscle or joint pain were significantly higher in women. The analysis revealed that a larger masseter CSA was significantly associated with bruxism only in men. The larger CSA was manifested only in the higher frequency bruxers.

CONCLUSIONS

Bruxism had heterogeneous effects on the masseter muscle between genders. Although a higher prevalence of bruxism was reported by women, the larger CSA of the masseter muscle was significantly higher in bruxing men but not in women. This study emphasizes the need for a gender-specific approach when evaluating the clinical implications of bruxism on the masseter muscle.

Relationships between orofacial pain and sleep: Analysis of UK biobank and genome-wide association studies data

Background/purpose

Orofacial pain is common in dental practices. This study aimed to explore relationships between orofacial pain and sleep using the UK Biobank dataset and, based on epidemiological associations, to investigate the causal association using genome-wide association studies data.

Materials and methods

First, a cross-sectional study was conducted with 196,490 participants from UK Biobank. Information on pain conditions and sleep traits was collected. Multivariable models were used to explore the relationships with odds ratio (OR). Second, Mendelian randomization analyses were conducted using data for orofacial pain, including temporomandibular joint disorders-related pain (n = 377,277) and atypical facial pain (n = 331,749), and sleep traits, including sleep duration (n = 446,118), short sleep (n = 411,934), long sleep (n = 339,926), snoring (n = 359,916), ease of getting up (n = 385,949), insomnia (n = 453,379), daytime dozing (n = 452,071), daytime napping (n = 452,633), and chronotype (n = 403,195).

Results

The cross-sectional study confirmed the bidirectionality between pain and sleep. Participants experiencing pain all over the body showed a significant association with an unhealthy sleep pattern (OR = 1.18, P < 0.001) and other sleep traits (P < 0.05). Risks of chronic orofacial pain were associated with sleep duration in a non-linear relationship (P = 0.032). The Mendelian randomization analyses indicated that long sleep was causally associated with temporomandibular joint disorders-related pain (OR = 6.77, P = 0.006).

Conclusion

The relationship between pain and sleep is bidirectional. Long sleep is found to be causally associated with chronic orofacial pain.

Comparison of the effects of acupuncture methods on the temporomandibular disorder: A network meta-analysis

OBJECTIVES

A network meta-analysis (NMA) was applied to compare the therapeutic effect of different acupuncture methods on temporomandibular disorder (TMD).

MATERIALS AND METHODS

A computer retrieval was carried out in the English databases of Cochrane, PubMed, Embase and Web of Science, as well as the Chinese databases of CNKI, Wanfang and VIP for randomized controlled trials on the effect of acupuncture on TMD, with a retrieval deadline of January 21, 2024. Data analysis was conducted using R software and Bayesian method. The pain score served as the primary outcome measure, with the mouth opening as the secondary outcome measure.

RESULTS

Thirty-five articles were included in the analysis, involving 1937 TMD patients. The NMA results suggested that DN-PT had the best effect on relieving pain and improving mouth opening. (Description of all abbreviations in Supplementary Material S3).

CONCLUSIONS

Based on the available evidence, the results of the NMA suggest that DN-PT is most effective in relieving TMD pain and increasing mouth opening. However, due to the fact that some acupuncture therapies are only reported in a small number of research reports, this may lead to an increase in the randomness of the results and a decrease in the reliability.

Substance Use Among Adults with Chronic Orofacial Pain

Chronic orofacial pain (COFP; i.e., musculoskeletal, neurovascular, or neuropathic pain in the face, mouth, or jaw that lasts for at least 3 months) is prevalent and debilitating. Chronic pain and substance use frequently co-occur, and individuals with COFP face unique challenges (e.g., uncertainty about future pain episodes, difficulty eating, drinking and talking) that may influence substance use. Nevertheless, no work to date has comprehensively assessed substance use among individuals with COFP. Here, we examine the prevalence of substance use among adults with COFP. Participants included 246 adults with COFP who were recruited from the Facial Pain Association. Participants completed an online survey that included a comprehensive assessment of substance use (i.e., Alcohol, Smoking, and Substance Involvement Screening Test) between December 2023 and January 2024. Most participants (82.9%) have used ≥ 1 substance in their lifetime, over two-thirds (68.3%) currently use ≥ 1 substance, and nearly half (43.5%) engage in risky substance use. The most commonly used substances were alcohol, tobacco, cannabis, opioids, and sedatives. This study presents a comprehensive assessment of substance use among adults with COFP. Findings extend prior work documenting high rates of substance use among individuals with chronic pain to a sample of adults with COFP. Given that substance use can exacerbate chronic pain and interfere with pain management, findings underscore the importance of assessing and addressing substance use among individuals with COFP.

Comparative study of the effects of ibuprofen, acetaminophen, and codeine in a model of orofacial postoperative pain in male and female rats

Pain management is a primary goal after oral surgeries, but little is known about sex differences in the sensitivity to analgesics. This study aimed to compare the efficacy of three drugs with analgesic potential on heat and mechanical hyperalgesia, spontaneous pain and locomotion on male and female rats subjected to a model of orofacial postoperative pain. Male and female Wistar rats were submitted to intraoral incision or sham surgery, and on postoperative day 3, the effect of the ibuprofen (30 and 100 mg/kg), acetaminophen (100 and 300 mg/kg) and codeine (3 and 10 mg/kg) was assessed on responses to heat and mechanical facial stimulation, facial grooming, and locomotion. Ibuprofen reduced heat and mechanical hyperalgesia and grooming behavior in male and female rats in a non-sedative dose; acetaminophen dose-dependently reduced the mechanical hyperalgesia and abolished the heat hyperalgesia and the grooming behavior but caused sedation in both sexes; codeine dose-dependently reduced the mechanical hyperalgesia in male and female rats, and reduced the heat hyperalgesia, but females were less sensitive than males. It reduced spontaneous facial grooming in both sexes, but induced hyperlocomotion in females. Ibuprofen presented the most favorable profile, since it reduced over 50% heat and mechanical hyperalgesia in male and female rats, and significantly reduced spontaneous pain, without causing sedation or affecting locomotion. The identification of sex differences in the sensitivity and safety profile of frequently used analgesics can help guide the choice of more effective individualized therapies for pain control.

Current thinking in the management of temporomandibular disorders in children: A narrative review

The aim of this narrative review is to discuss current opinions on paediatric temporomandibular disorders (TMDs) due to their increasing incidence in routine secondary care maxillofacial clinics. A MEDLINE and EMBASE search was performed of the literature published in the past three years concerning paediatric TMD. Of 261 papers identified, 89 were selected for relevance, of which 52 full texts were eligible and 41 included. The narrative of this paper follows three domains: myogenous and arthogenous pain, juvenile idiopathic arthritis (JIA), and reconstruction. The principles of treating mild TMD in children are similar to those in adults, with even more emphasis on the management of psychosocial issues and self-care. The use of medication, however, needs to be more cautious. Symptomatic disc displacement should be treated to reduce inflammation, so early arthrocentesis or arthroscopy is relevant. Controversy exists on disc repositioning to reduce or even reverse condylar degeneration in the growing condyle. If undertaken it should ideally be performed arthroscopically by surgeons with significant experience. Arthritic disease is usually associated with JIA so a multidisciplinary approach is the focus of treatment. The role of arthroscopy in the management of symptoms is increasing but it does not prevent disease progression. Surgical correction may be required for secondary deformity. Reconstruction remains a challenge with no ideal autogenous method. Alloplastic joints are gaining popularity, but the long-term outcomes are unknown. Surgery can be undertaken with minimal morbidity, and the use of joint replacements, even as space maintainers, may therefore be more beneficial than repeated failed autogenous treatments.

Cervical Spinal Cord Stimulation for Treatment of Sympathetically Mediated Orofacial Pain: Case Series and Narrative Review

OBJECTIVES

Sympathetically mediated orofacial pain is a rare form of craniofacial pain that may be refractory to conventional medical management. We report two cases of orofacial pain with sympathetic features treated with cervical spinal cord stimulation (SCS) using burst waveform with passive recharge. In addition, we present a narrative review of cervical SCS use in the management of orofacial pain.

MATERIALS AND METHODS

The MEDLINE (PubMed) data base was queried for studies of orofacial pain and cervical SCS by searching applicable keywords including "face," "facial pain," "trigeminal neuralgia," "complex regional pain syndrome," and "spinal cord stimulation." Studies in the English language published between January 1, 2010 and December 31, 2023 were reviewed for relevance.

RESULTS

Our literature review identified eight studies of cervical SCS use for treating orofacial pain. Our case series and literature review indicate that cervical SCS is probably safe and promising in the treatment of orofacial pain unresponsive to conventional management. Prior studies report positive results in patients with trigeminal nerve-related pain but are retrospective, include a small sample size, and are heterogenous regarding the follow-up period. We report significant analgesia in two patients with sympathetically mediated orofacial pain treated with cervical SCS using burst waveform with passive recharge.

CONCLUSIONS

Cervical SCS is a viable therapeutic option for patients with orofacial pain syndromes including those with sympathetic features, although further randomized clinical studies are warranted that should include a comprehensive set of outcomes measuring pain intensity, physical function, emotional function, quality of life, and general well-being.

The Effect of Experimentally Induced Pain in the Cervical, Shoulder, or Orofacial Regions on Cervical Neuromuscular and Kinematic Features: A Systematic Review and Meta-analysis

In this systematic review, we synthesize the literature investigating the effect of experimentally induced pain in the cervical, shoulder, or orofacial regions on cervical neuromuscular and kinematic features. Databases were searched up to November 1, 2023. A total of 29 studies using hypertonic saline injection (n = 27) or glutamate injection (n = 2) as experimental pain models were included. Meta-analyses revealed reduced upper trapezius activation during shoulder flexion/abduction when pain was induced in the upper trapezius (standardized mean difference: -.90, 95% confidence interval: [-1.29; -.51]), splenius capitis (-1.03 [-1.44; -.63]), and supraspinatus (-.63 [-1.25; -.01]), but not in the subacromial space (.22 [-.16; .60]). Furthermore, experimentally induced pain caused a caudal redistribution of activation within the upper trapezius (.96 [.58; 1.34]) but did not change the mediolateral distribution (.11 [-.22; .42]). None of these adaptations persisted after pain resolution. Low-quality evidence supported the absence of an effect of experimental pain on upper trapezius muscle activation during manual dexterity and cervical flexion/extension tasks, as well as on cervical flexor and extensor muscle activation during cervical and jaw tasks. Inconsistent and limited evidence, attributed to the large heterogeneity of task and outcomes, precluded drawing meaningful conclusions about the effects of experimentally induced pain in the cervical region on cervical kinematics. Overall, cervical muscle activation tended to decrease in response to experimentally induced pain, and the decrease of muscle activation depended on the location of the painful stimulus. These adaptations are only partially representative of muscle activation patterns observed in clinical populations. PERSPECTIVE: This systematic review and meta-analysis revealed a reduced or unchanged muscle activation during experimental pain in the cervical, shoulder, or orofacial regions, depending on the task and location of nociceptive stimulation. There was inconsistent evidence on cervical kinematics. These findings enhance our understanding of neuromuscular adaptations to acute experimental pain.

Gender variability in palpation performance for temporomandibular disorders with three different methods: An experimental study

Gender differences in pain reporting and prevalence have been demonstrated. As gender of examiner also affects reporting of pain on palpation, the aim of this study was to evaluate the effects of examiner gender on palpation performance using three different palpation methods. Examiners of both genders were instructed on the correct technique for each palpation method by either a female or male instructor. The target was to achieve a pressure of 100 kPa, corresponding to the 1 kg of force for muscle palpation described in the diagnostic criteria for temporomandibular disorders (DC/TMD). All examiners performed traditional palpation with the index finger, palpation with a palpometer, and a novel bimanual palpation with visual feedback, in a randomized order. The examiner's gender, and its interaction with the gender of the instructor did not significantly affect magnitude, accuracy, or precision of the pressure applied. The method of palpation was the only factor that significantly impacted all metrics. The palpometer achieved the lowest palpation magnitude (mean pressure applied = 113.7  kPa, 95% CI: 109.8-117.6), the highest accuracy (absolute difference = 15.7  kPa, 95% CI: 12.3-19.1), and the highest precision (mean coefficient of variation = 6.8, 95% CI: 6.0-7.6), followed by bimanual palpation and traditional palpation. The results suggest that gender differences in pain reporting in patients are not likely to be a result of the technical aspects associated with the gender of the examiner. Instead, these differences may be attributed to other factors, such as sociocultural influences.

Temporomandibular disorder pain is associated with increased sick leave and reduced health related quality of life

BACKGROUND

Temporomandibular disorders (TMD) are the most common reason for chronic pain in the orofacial area and significantly impact the lives of those affected. The role of lifestyle factors in TMD, however, remains less explored. This cohort study aims to estimate TMD prevalence by addressing potential selection biases and to evaluate the association between TMD and lifestyle factors with a specific focus on sick leave and health related quality of life.

METHODS

By linking data on TMD in the general population in Västerbotten, northern Sweden (n = 180,000) to health survey data (n = 120,000), information on sociodemographic factors and quality of life was available for 52,961 individuals (50.6% women) with a mean age of 53 years. We applied inverse probability weighting to adjust for selection bias and Poisson regression to explore associations with TMD.

RESULTS

TMD prevalence was 9.2% during the study period, being higher in women (12.9%) than men (5.4%). Weighting for varying visiting frequencies did not affect TMD prevalence (average difference 0.4% points). Individuals with TMD, especially women, reported more sick leave and use of pain medication, with a significant association between TMD and increased sick leave (prevalence ratio 1.89, 95% CI: 1.78-2.01) among both women and men. In addition, TMD was associated with a lower health related quality of life (p < 0.001).

CONCLUSION

The association of TMD with sick leave highlights the condition's profound impact on the lives of affected individuals. These findings underscore the influence of TMD on work life and the burden of TMD on the societal level.

SIGNIFICANCE STATEMENT

The findings provide insight into how TMD affect individuals, by incorporating lifestyle factors, social determinants and the impact of sick leave at a population level. By incorporating these areas into the study of TMD, we can deepen our understanding of how TMD affects individuals' lives. This approach may also create opportunities to develop more comprehensive strategies to address TMD, focusing on broader implications beyond the clinical symptoms.

Correlation Between Orofacial Pain and Sensory and Autonomic Neuropathies

Purpose

Orofacial Pain (OFP) affects 15% of the general population. OFP conditions can be myofascial, also known as temporomandibular disorders (TMDs) or neuropathic. The underlying pathophysiology in several chronic OFP conditions, is unknown. Small fiber neuropathy (SFN) is a disorder of thinly myelinated A-delta and non-myelinated C-fibers and can manifest as sensory and autonomic neuropathies. SFN has been demonstrated in some OFP conditions. Our study aims to assess the presence of OFP in patients with sensory and autonomic neuropathies and assess the correlation between OFP, skin biopsy and autonomic dysfunction.

Patients and Methods

This is a retrospective study (2018-2020) of patients from the SFN registry, Massachusetts General Hospital, Boston, USA, for the presence of OFP. All patients were included. Primary outcome: Prevalence of OFP in patients with chronic neuropathies. Secondary outcomes: Correlation between OFP and skin biopsy, dysautonomia, headaches, chronic nociceptive pain, psychological conditions, and patient factors, such as mean age and BMI.

Results

Charts of 450 patients with sensory and autonomic neuropathies were reviewed. 22.67% (n=102) had OFP. The mean (range) age at biopsy in patients with OFP was 48.36 (20-81) years, female: male ratio 3.25:1. More OFP patients had negative skin biopsy results (p value<0.05) than those with sensory neuropathies. Patients with OFP had significantly higher prevalence of psychological conditions (p value 0.000), and higher BMI >30 (p value 0.025). Dysautonomia was significantly higher in patients with TMDs when compared to the ones without TMDs (p value 0.030). There was no significant difference in mean age, gender predilection, presence of headaches, peripheral neuropathies, and nociceptive pain between patients with and without OFP.

Conclusion

OFP and sensory neuropathies can be overlapping conditions. Patients presenting with concomitant TMD and dysautonomia can be further tested for SFN. This can further help us understand a correlation if any, between idiopathic TMD/OFP conditions and SFN and further our understanding of the pathophysiology of these conditions.

Incidence, diagnosis, and management of orofacial pain among new patients receiving tertiary care in Thailand: A 6-year retrospective study comparing before and during the COVID-19 outbreak

BACKGROUND

There is insufficient data on orofacial pain related to the COVID-19 outbreak in Thailand.

OBJECTIVE

To investigate the incidence, diagnosis and management of orofacial pain among new patients over the last 6 years, before and during the COVID-19 outbreak.

METHODS

Medical records from new patients who first visited Chulalongkorn Dental Hospital between 2017 and 2022 were retrospectively investigated. The sample size was determined, and proportional stratified random sampling was employed to distribute the sample number proportionally across each year. The hospital number of each patient was randomised using online software as a sampling strategy. A data collection form was developed and used to gather information from the digital data system.

RESULTS

At the first visit, 770 out of 1359 patients (56.7/100 people, 95% CI: 54.0-59.3) reported orofacial pain defined as acute, chronic and unclassified pain. The most common chief complaints based on the AAOP classification were odontogenic pain (90.00%) and temporomandibular disorders (6.10%). The top three provisional modified ICD-10-TM diagnoses among these patients were pulp diseases (21.95%), impacted teeth (20.65%) and dental caries (9.09%). 81.87% of dental students' provisional diagnoses matched the final diagnoses given by dental specialists. Only 63.38% of orofacial pain patients were completely managed during the COVID-19 pandemic with common procedures being surgical removal, extraction and root canal therapy.

CONCLUSION

Half of Thai dental patients seeking tertiary care at a university dental hospital reported orofacial pain, which was not impacted by the COVID-19 pandemic. In contrast, dysfunction-related problems in the orofacial area significantly increased during the pandemic.

Role of HDAC5 Epigenetics in Chronic Craniofacial Neuropathic Pain

The information provided from the papers reviewed here about the role of epigenetics in chronic craniofacial neuropathic pain is critically important because epigenetic dysregulation during the development and maintenance of chronic neuropathic pain is not yet well characterized, particularly for craniofacial pain. We have noted that gene expression changes reported vary depending on the nerve injury model and the reported sample collection time point. At a truly chronic timepoint of 10 weeks in our model of chronic neuropathic pain, functional groupings of genes examined include those potentially contributing to anti-inflammation, nerve repair/regeneration, and nociception. Genes altered after treatment with the epigenetic modulator LMK235 are discussed. All of these differentials are key in working toward the development of diagnosis-targeted therapeutics and likely for the timing of when the treatment is provided. The emphasis on the relevance of time post-injury is reiterated here.

Prevalence and management of neuropathic injury caused by dental implant insertion in mandible: a systematic review

To synthesize scientific knowledge regarding the prevalence of neuropathies and nerve injuries caused by dental implant placement in mandible and the available management. Observational and interventional studies evaluating neuropathies occurrence in adults who underwent dental implant surgery were included. Any neuropathy diagnostic was accepted. The searches were conducted in six databases and grey literature. Methodological quality was screened using the Joanna Briggs Institute. The resulting synthesis was a narrative summary, and prevalence meta-analyses were performed in MetaXL 5.3. Among 98 full texts assessed, 38 studies were included. Neuropathies were diagnosed by questionnaires and/or clinical assessment. Eighteen studies presented high, sixteen moderate, and four low methodological quality. In implant surgeries without nerve lateralization, 12% and 5% of the patients may experience neuropathy during the first week and after three months, respectively. In implant surgeries with nerve lateralization, the prevalence was from 90% in the first week to 42% after three months. Proposed management included drugs, laser therapy and dental implant removal. In mandible, the prevalence of neuropathies in dental implant surgeries without lateralization is lower when compared with those with lateralization (eight times more in both follow-up times). The most frequent treatment was pharmacologic management.

Anxiety, pain catastrophizing, and pain outcomes among older adults with chronic orofacial pain

Although chronic orofacial pain (COFP) is common among older adults, the role of psychological factors in pain outcomes among this population has received limited attention. This study examined the role of anxiety and pain catastrophizing, two corelates of pain in other populations, in pain intensity and interference among 166 older adults with COFP (79% female, Mage = 68.84, SD = 5.56). Participants completed an online survey including measures of anxiety, pain catastrophizing, and pain intensity/interference. We applied mediation analyses to test indirect associations between anxiety and pain outcomes via pain catastrophizing. Results indicated that anxiety was positively associated with pain intensity and pain interference (bs = .70-1.12, ps < .05). There was also an indirect association between anxiety and pain interference through pain catastrophizing (b = .35, 95% CI [.0383, .7954]), indicating pain catastrophizing partially accounts for this relationship. Assessing and addressing anxiety and pain catastrophizing has the potential to improve treatment outcomes in this population.

Methyl jasmonate ameliorates pain-induced learning and memory impairments through regulating the expression of genes involved in neuroinflammation

OBJECTIVE

Orofacial pain with high prevalence is one of the substantial human health issues. The importance of this matter became more apparent when it was revealed that orofacial pain, directly and indirectly, affects cognition performances. Currently, researchers have focused on investigating pharmaceutics to alleviate pain and ameliorate its subsequent cognitive impairments.

DESIGN

In this study, the rats were first treated with the central administration of methyl jasmonate (MeJA), which is an antioxidant and anti-inflammatory bio-compound. After 20 min, orofacial pain was induced in the rats by the injection of capsaicin in their dental pulp. Subsequently, the animals' pain behaviors were analyzed, and the effects of pain and MeJA treatments on rats learning and memory were evaluated/compared using the Morris water maze (MWM) test. In addition, the expression of tumor necrosis factor-α (TNF-α), IL-1β, BDNF, and COX-2 genes in the rats' hippocampus was evaluated using real-time polymerase chain reaction.

RESULTS

Experiencing orofacial pain resulted in a significant decline in the rats learning and memory. However, the central administration of 20 μg/rat of MeJA effectively mitigated these impairments. In the MWM, the performance of the MeJA-treated rats showed a two- to threefold improvement compared to the nontreated ones. Moreover, in the hippocampus of pain-induced rats, the expression of pro-inflammatory factors TNF-α, IL-1β, and COX-2 significantly increased, whereas the BDNF expression decreased. In contrast, MeJA downregulated the pro-inflammatory factors and upregulated the BDNF by more than 50%.

CONCLUSIONS

These findings highlight the notable antinociceptive potential of MeJA and its ability to inhibit pain-induced learning and memory dysfunction through its anti-inflammatory effect.

Objectively measured adherence may affect side effects of mandibular advancement therapy in subjects with obstructive sleep apnea

PURPOSE

The purpose of this study was to determine if objectively measured adherence to oral appliance (OA) treatment may affect dental changes and temporomandibular disorders (TMD) in patients with obstructive sleep apnea (OSA).

METHODS

The original study group consisted of adults with OSA who were referred for OA therapy. Eight indicators of subjective side effects of using OA (temporomandibular joint (TMJ) and muscle pain, pain in teeth, jaw stiffness in the morning, clicking, dry mouth, hypersalivation, gingival irritation) were evaluated by a questionnaire. Three occlusal indicators (overjet, overbite, molar occlusion) and clinical TMD signs (TMJ pain, muscle pain, clicking, jaw deviation on opening) were evaluated at baseline and at the 3-, 6-, and 12-month follow-up. In addition, objective adherence monitoring for OA was registered. Statistical analyses included the chi-square test, Fisher's exact test, paired sample t-test, and linear regression analyses.

RESULTS

A total of 58 adults with OSA were referred for OA therapy. Mean (SD) age was 50.7 (11.7) and mean apnea-hypopnea index (AHI) was 19.5 (10.0). At 1-year follow-up, the study group consisted of 28 men and 12 women. Overjet but not overbite reduced significantly after 1-year OA therapy. The average nightly wear of OA was related to overjet and overbite reduction, and to TMD signs. Hypersalivation, dry mouth, and tooth discomfort were the most common subjective side effects of OA therapy.

CONCLUSION

There was a time-dependent relationship with the nightly wear of OA and reduction in overjet and overbite, and clinical TMD signs. With 60% of mandibular advancement, dental changes and TM-disorders were considered mild/minor in the 1-year study period.

Factors associated with voice-related quality of life among patients with temporomandibular disorders

BACKGROUND

Research would be important for obtaining a better understanding of voice complaints among patients with temporomandibular disorders (TMD).

OBJECTIVE

The identification of predictors of voice disorders associated with TMD pain was made according to Diagnostic Criteria for TMD (DC/TMD) Axis I.

METHODOLOGY

Functional limitations were measured using the Jaw Functional Limitation Scales for mastication (JFLS-M), jaw mobility (JFLS-JM), and verbal and emotional expression (JFLS-VEE). Patients also completed the Hospital Anxiety and Depression Scale (HADS). The primary outcome was social-emotional and physical functioning as indicated by scores on the Voice-Related Quality of Life (V-RQOL) questionnaire. Multiple linear regression was used to model the relationship between the domains on the V-RQOL questionnaire and scores on the HADS and JFLS after adjusting for age, gender, DC/TMD diagnosis, pain intensity, and time since pain onset.

RESULTS

The HADS-D (B=-1.15; 95% CI, -1.718 to -0.587; p<.001) and JFLS-VEE (B=-0.22; 95% CI, -0.40 to -0.06; p=.008) were significant predictors of scores on the V-RQOL questionnaire.

CONCLUSION

Higher scores on depression measures and limitations in verbal and emotional expression could exacerbate voice problems among TMD pain patients. Future research should promote multidisciplinary treatments for TMD pain-related voice disorders.

Sex differences in descending control of nociception (DCN) responses after chronic orofacial pain induction in rats and the contribution of kappa opioid receptors

Descending control of nociception (DCN), a measure of efficiency of descending pain inhibition, can be assessed in animals by the combined application of test and conditioning noxious stimuli. Evidence from pre-clinical and clinical studies indicates that this mechanism of pain control may differ between sexes and might be impaired in many chronic pain states. However, little is known about sex differences in DCN efficiency in models of acute and chronic orofacial pain. Herein, we first evaluated DCN responses in male and female rats by the applying formalin into the upper lip or capsaicin into the forepaw as the conditioning stimulus, followed by mechanical stimulation (Randall-Selitto) of the hind paw as the test stimulus. The same protocol (i.e., capsaicin in the forepaw followed by mechanical stimulation of the hind paw) was evaluated in male and female rats on day 3 after intraoral incision and on day 15 and 30 after chronic constriction injury of the infraorbital nerve (CCI-ION). Additionally, we assessed the effect of the kappa opioid receptor (KOR) antagonist Norbinaltorphimine (nor-BNI) on DCN responses of female nerve-injured rats. This study shows that naïve female rats exhibit less efficient DCN compared to males. Postoperative pain did not alter DCN responses in female and male rats, but CCI-ION induced loss of DCN responses in females but not in males. Systemic pretreatment with nor-BNI prevented the loss of DCN induced by CCI-ION in female rats. The results reveal sex differences in DCN responses and female-specific impairment of DCN following chronic orofacial pain. Moreover, the findings suggest that, at least for females, blocking KOR could be a promising therapeutic approach to prevent maladaptive changes in chronic orofacial pain.

Whiplash trauma did not predict jaw pain after 2 years: an explorative study

OBJECTIVES

To explore predictive factors for the development and maintenance of jaw pain over a 2-year period.

METHODS

One hundred nineteen cases (73 women) and 104 controls (59 women), mean age 34.9 years (SD 13.9), attended baseline and 2-year follow-up examinations. The whiplash cases visited the emergency department at Umeå University Hospital, Sweden, with neck pain within 72 h following a car accident, and baseline questionnaires were answered within a month after trauma. Controls were recruited via advertising. Inclusion criteria were age 18-70 years, living in Umeå municipality and Swedish speaking. The exclusion criterion was neck fracture for cases and a previous neck trauma for controls. Validated questionnaires recommended in the standardized Research Diagnostic Criteria for temporomandibular disorders were used. Jaw pain was assessed by two validated screening questions answered with "yes" or "no." A logistic regression analysis was used to predict the outcome variable jaw pain (yes/no) after 2 years.

RESULTS

Whiplash trauma did not increase the odds of development of jaw pain over a 2-year period (OR 1.97, 95% CI 0.53-7.38). However, non-specific physical symptoms (OR 8.56, 95% CI 1.08-67.67) and female gender (OR 4.89, 95% CI 1.09-22.02) did increase the odds for jaw pain after 2 years.

CONCLUSION

The development and maintenance of jaw pain after whiplash trauma are primarily not related to the trauma itself, but more associated with physical symptoms.

CLINICAL RELEVANCE

The development of jaw pain in connection with a whiplash trauma needs to be seen in a biopsychosocial perspective, and early assessment is recommended.

Epigenetic HDAC5 Inhibitor Reverses Craniofacial Neuropathic Pain in Mice

Identifying and resolving molecular complexities underlying chronic neuropathic pain is a significant challenge. Among the numerous classes of histone deacetylases, Class I (HDAC 1-3) and Class III (sirtuins) have been best studied in experimental pain models where inhibitor pre-treatments but not post-treatments abrogate the development of pain-related behaviors. Post-treatment here in week 3 with less well-studied Class IIa HDAC4/5 selective inhibitor LMK235 diminishes the trigeminal ganglia increases of HDAC5 RNA and protein in two chronic orofacial neuropathic pain models to levels measured in naïve mice at week 10 post-model induction. HDAC4 RNA reported in lower limb inflammatory pain models is not evident in the trigeminal models. Many other gene alterations persisting at week 10 in the trigeminal ganglia (TG) are restored to naïve levels in mice treated with LMK235. Important pain-related upregulated genes Hoxc8,b9,d8; P2rx4, Cckbr, growth hormone (Gh), and schlafen (Slfn4) are greatly reduced in LMK235-treated mice. Fold increase in axon regeneration/repair genes Sostdc1, TTr, and Folr1 after injury are doubled by LMK235 treatment. LMK235 reduces the excitability of trigeminal ganglia neurons in culture isolated from nerve injured mice compared to vehicle-treated controls, with no effect on neurons from naïve mice. Electrophysiological characterization profile includes a shift where ∼20% of the small neurons recorded under LMK235-treated conditions are high threshold, whereas none of the neurons under control conditions have high thresholds. LMK235 reverses long-standing mechanical and cold hypersensitivity in chronic trigeminal neuropathic pain models in males and females (5,10 mg/kg), preventing development of anxiety- and depression-like behaviors. PERSPECTIVE: Data here support HDAC5 as key epigenetic factor in chronic trigeminal neuropathic pain persistence, validated with the study of RNA alterations, TG neuronal excitability, and pain-related behaviors. HDAC5 inhibitor given in week 3 restores RNA balance at 10 weeks, while upregulation remains for response to wound healing and chronic inflammation RNAs.

Clinical aspects of mastication myalgia-an overview

Mastication myalgia is the most common cause of non-odontogenic pain in the orofacial region and is often associated with a reduced quality of life. The purpose of this review is to provide an overview of the clinical aspects of myalgia based on available research. The review includes epidemiological, diagnostic, and etiological aspects. In addition, the potential risk factors related to the transition from acute to chronic myalgia are explored and treatment strategies are presented for its management. As a result, this review may increase clinical knowledge about mastication myalgia and clarify strategies regarding prevention, diagnostics, and management to improve prognosis and reduce patient suffering.

Association Between Orofacial Pain and Anxiety: A Systematic Review

The prevalence of orofacial pain continues to increase. Additionally, the rising number has been accompanied by reduced quality of life of its sufferers. An assumed association between orofacial pain and anxiety has surfaced due to the results of several studies that show higher occurrence of anxiety in people experiencing orofacial pain, compared to those who are orofacial-pain-free. The aim of this systematic review was to discover past research on orofacial pain and its relationship to anxiety, and to understand the relationship between acute and chronic orofacial pain and anxiety. The current systematic review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) rules. Study searches were carried out using three databases, namely PubMed, ScienceDirect, and Scopus. Article selection was carried out in several stages and was based on inclusion and exclusion criteria and continued by assessing the methodological quality and risk of bias of each article. The risk of bias was analyzed by using the critical review tool for cross-sectional studies from the Joanna Briggs Institute (JBI). The selection process led to a review process of 13 cross-sectional research articles. The systematic review showed a positive relationship between orofacial pain and anxiety, with variations in the strength of the relationship (weak to moderate). Most articles revealed that anxiety is a risk factor for orofacial pain. A correlation between chronic orofacial pain and anxiety was mentioned in several studies. It can be concluded that there is an existing relationship between orofacial pain and anxiety, especially chronic orofacial pain. Prospero registration number: CRD42023385409.

Thermographic findings related to facial pain - a survey of 40 subjects

OBJECTIVE

The purpose of this study was to assess how thermography findings relate painful symptoms and signs of temporomandibular disorders (TMD).

METHODS

Thermography, combined with chewing of paraffin wax, was performed on 40 subjects. The results were analyzed according to gender and pain-related TMD symptoms and clinical signs.

RESULTS

The overall temperatures after chewing were higher in TMD patients than in controls. For females, the most significant findings were the thermal increase between the relaxed state and subjects' state after chewing in temporal and temporomandibular joint (TMJ) regions. For males, all calculated parameters demonstrated a poor ability to discriminate TMD from controls.

CONCLUSION

Thermography could be a potential tool in diagnostics of female TMD patients. The results suggest that the thermal information assessed in specific facial areas could help to discriminate TMD patients from non-TMD patients and could be used to quantify the pain associated with TMD.

Smartphone application to report awake bruxism: Development and testing of the Swedish version and a pilot study to evaluate family history in young adults and their parents

BACKGROUND

Together with psychosocial and hereditary factors, bruxism is a possible risk factor for orofacial pain. Bruxism is defined as a masticatory muscle activity characterized by repetitive or sustained tooth contact, or by bracing or thrusting of the mandible. A smartphone application to report awake bruxism (AB) has been developed and translated into more than 25 languages.

OBJECTIVE(S)

To translate the application into Swedish, adapt it to Swedish culture and conduct a study to evaluate the usability of the application for studies on family history and associated risk factors.

METHODS

Translation and cultural adaption of the Swedish version of the application (BruxApp) was carried out in a four-step sequential process. Ten young adults (22-30 years) were recruited together with ten parents (42-67 years) and reported their AB with the application over two seven-day periods. Pain, stress and parafunctional behaviours were assessed by questionnaires.

RESULTS

The back translation check showed minimal discrepancies between the translation and the English version. Participants did not report any problems with the application. Response rates for both groups were 65%. A difference in frequency of AB was shown between young adults and parents (22.0% vs. 12.5%, p < .001). A positive moderate correlation was found between AB and stress (r = 0.54, p = .017).

CONCLUSION

The use of application strategies enables data collection on AB which can be used in both clinical and research settings. The results suggest that the Swedish version is ready for implementation and for studies on the relationships between AB, family history and psychosocial factors.

Involvement of the Transient Receptor Channels in Preclinical Models of Musculoskeletal Pain

BACKGROUND

Musculoskeletal pain is a condition that affects bones, muscles, and tendons and is present in various diseases and/or clinical conditions. This type of pain represents a growing problem with enormous socioeconomic impacts, highlighting the importance of developing treatments tailored to the patient's needs. TRP is a large family of non-selective cation channels involved in pain perception. Vanilloid (TRPV1 and TRPV4), ankyrin (TRPA1), and melastatin (TRPM8) are involved in physiological functions, including nociception, mediation of neuropeptide release, heat/cold sensing, and mechanical sensation.

OBJECTIVE

In this context, we provide an updated view of the most studied preclinical models of muscle hyperalgesia and the role of transient receptor potential (TRP) in these models.

METHODS

This review describes preclinical models of muscle hyperalgesia induced by intramuscular administration of algogenic substances and/or induction of muscle damage by physical exercise in the masseter, gastrocnemius, and tibial muscles.

RESULTS

The participation of TRPV1, TRPA1, and TRPV4 in different models of musculoskeletal pain was evaluated using pharmacological and genetic tools. All the studies detected the antinociceptive effect of respective antagonists or reduced nociception in knockout mice.

CONCLUSION

Hence, TRPV1, TRPV4, and TRPA1 blockers could potentially be utilized in the future for inducing analgesia in muscle hypersensitivity pathologies.

Treatments for painful temporomandibular disc displacement with reduction: a network meta-analysis of randomized clinical trials

There is currently no consensus on the best treatment for painful temporomandibular disc displacement with reduction (DDwR), and no network meta-analysis of randomized clinical trials (RCTs) comparing all types of treatment for this condition has been conducted. The objective of this study was to compare and rank all treatments for DDwR, including conservative treatments, occlusal splints, low-level laser therapy (LLLT), manual therapy, no treatment (control), arthrocentesis (Arthro) alone, Arthro plus intra-articular injection of platelet-rich plasma (Arthro-PRP) or hyaluronic acid (Arthro-HA), and Arthro plus occlusal splint. Predictor variables were pain intensity and maximum mouth opening (MMO). The mean difference with 95% confidence interval was estimated using Stata software. The GRADE system was used to assess the certainty of the evidence. Twenty RCTs reporting 1107 patients were identified in the literature search; 980 of these patients were included in the network meta-analysis. Direct meta-analysis showed that Arthro-PRP significantly reduced pain intensity compared to Arthro alone, while occlusal splint and manual therapy were superior to conservative treatment (all very low quality evidence). Arthro with intra-articular injection of PRP/HA ranked as the most effective treatment in terms of pain reduction, whereas LLLT ranked the best choice for increasing MMO for patients with DDwR. However, it is important to note that the evidence for the superiority of these treatments is generally of very low quality. Therefore, further high-quality research is needed to confirm these findings and provide more reliable recommendations for the treatment of DDwR.

Pharmacological Treatments of Temporomandibular Disorders: A Systematic Review Including a Network Meta-Analysis

OBJECTIVE

Temporomandibular disorders (TMD) comprise a cluster of conditions with a wide range of etiological factors that causes pain and discomfort in the masticatory muscles (TMD-M) and temporomandibular joints (TMD-J). More than 50% of the patients with TMD report regular usage of drugs. However, there is still no consensus, nor is there any evidence-based support for clinicians when choosing between different drugs. Therefore, this systematic review, including a network meta-analysis (NMA), aimed to evaluate the scientific evidence and discuss the pharmacological treatment options available to treat painful TMD.

METHOD

An electronic search was undertaken to identify randomized controlled trials (RCTs) investigating pharmacological treatments for TMD-M and/or TMD-J, published until 6 April 2023. Since only 11 articles could be used for an NMA regarding TMD-M, a narrative synthesis was also performed for all 40 included RCTs. The quality of evidence was rated according to Cochrane's tool for assessing risk of bias, while the certainty of evidence was rated according to Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

When it comes to TMD-M, evidence arises for wet needling therapies with BTX-A, granisetron, and PRP as well as muscle relaxants. For TMD-J, evidence points toward pharmacological treatment approaches including non-steroidal antiinflammatory drugs (NSAIDs) and glucocorticosteriods (for inflammatory conditions) as well as hyaluronic acid and dextrose.

CONCLUSIONS

The evidence clearly indicates that the pharmacological treatment approaches differ between TMD-M and TMD-J. Therefore, it is of great importance to first try to uncover each patient's individual and multifactorial etiology and then employ a multifaceted treatment strategy, including pharmacological treatment approaches.

Advancements in Understanding and Classifying Chronic Orofacial Pain: Key Insights from Biopsychosocial Models and International Classifications (ICHD-3, ICD-11, ICOP)

In exploring chronic orofacial pain (COFP), this review highlights its global impact on life quality and critiques current diagnostic systems, including the ICD-11, ICOP, and ICHD-3, for their limitations in addressing COFP's complexity. Firstly, this study outlines the global burden of chronic pain and the importance of distinguishing between different pain types for effective treatment. It then delves into the specific challenges of diagnosing COFP, emphasizing the need for a more nuanced approach that incorporates the biopsychosocial model. This review critically examines existing classification systems, highlighting their limitations in fully capturing COFP's multifaceted nature. It advocates for the integration of these systems with the DSM-5's Somatic Symptom Disorder code, proposing a unified, multidisciplinary diagnostic approach. This recommendation aims to improve chronic pain coding standardization and acknowledge the complex interplay of biological, psychological, and social factors in COFP. In conclusion, here, we highlight the need for a comprehensive, universally applicable classification system for COFP. Such a system would enable accurate diagnosis, streamline treatment strategies, and enhance communication among healthcare professionals. This advancement holds potential for significant contributions to research and patient care in this challenging field, offering a broader perspective for scientists across disciplines.

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.

Socioeconomic Characteristics Associated With the Development of Chronic Pain After Pain Interference Experienced in Early Adulthood

OBJECTIVE

Predictors of pain persistence have been identified among patients undergoing treatment for chronic pain or related conditions, but correlates of pain persistence in the general population remain underexplored. We identify socioeconomic variables associated with pain onset or persistence over a 6 to 10 year period in a nationally representative cohort.

METHODS

Using panel data from the National Longitudinal Survey of Youth-1997, we examined the presence of pain interference at age 29 and chronic pain at ages 35 to 39. Persistent pain was defined as pain present at both interview time points; new-onset pain was defined as pain not reported at age 29, but present at ages 35 to 39; and transient pain was defined as experiencing pain interference at age 29 with no report of chronic pain at ages 35 to 39.

RESULTS

Based on a sample of 6188 participants, we estimated that 4% experienced persistent pain, 11% experienced transient pain, and 7% experienced new-onset pain. Pain persistence was less likely among non-Hispanic Black respondents but more likely among formerly married respondents and those with poor health, health-related work limitation, or greater pain interference at the age 29 baseline. New-onset pain was most likely among female respondents, respondents with some college education, and respondents with poor self-rated health or obesity at baseline.

DISCUSSION

Development of chronic pain by the mid-late 30s was common among young adults experiencing pain interference at age 29. Race/ethnicity, gender, and educational attainment exhibited different associations with persistence as compared with new onset of pain problems.

Effect on orofacial pain in patients with chronic pain participating in a multimodal rehabilitation programme - a pilot study

OBJECTIVES

Orofacial pain in patients taking part in a multimodal rehabilitation programme (MMRP) due to chronic bodily pain is common but it is not known whether such a rehabilitation programme can also have an effect on the presence of orofacial pain. The first aim of this study was to evaluate the effect of an MMRP on orofacial pain frequency. The second aim was to evaluate differences in the effect on quality of life and on psychosocial factors related to chronic pain.

METHODS

MMRP was evaluated through validated questionnaires from the Swedish Quality Registry for Pain Rehabilitation (SQRP). Fifty-nine patients participating in MMRP filled out the two screening questions for orofacial pain in addition to the SQRP questionnaires before and after participation in MMRP during the period August 2016 to March 2018.

RESULTS

Pain intensity decreased significantly after the MMRP (p=0.005). Fifty patients (69.4 %) reported orofacial pain before MMRP and no significant decrease after the programme (p=0.228). Among individuals with orofacial pain, the self-reported level of depression decreased after participation in the programme (p=0.004).

CONCLUSIONS

Even though orofacial pain is common among patients with chronic bodily pain, participation in a multimodal pain programme was not enough to reduce frequent orofacial pain. This finding implies that specific orofacial pain management including information about jaw physiology could be a justified component of patient assessment prior to a multimodal rehabilitation programme for chronic bodily pain.

Association between medication-induced xerostomia and orofacial pain: a systematic review

OBJECTIVE

Xerostomia (or oral dryness) is most commonly caused by medications that affect saliva secretion, and is often accompanied by symptoms of orofacial pain. Medication-induced xerostomia may or may not be associated with objectively demonstrable hyposalivation. The present study attempted to systematically identify an association between medication-induced xerostomia and orofacial pain.

METHOD AND MATERIALS

A systematic search was conducted using the following databases: WoS, PubMed, SCOPUS, and MEDLINE. The search terms used were: xerostomia OR "dry mouth" AND medication AND ("oral pain" OR "orofacial pain" OR "craniofacial pain" OR "burning mouth" OR "glossodynia") NOT Sjögren's NOT cancer. Inclusion criteria were medication-induced xerostomia and reported symptoms of orofacial pain. Four researchers performed the selection process and quality assessment and two researchers conducted data extraction.

RESULTS

Seven studies with a total of 1,029 patients were included. These studies were conducted between 2009 and 2022 and consisted of cross-sectional studies, case-control studies, and one randomized crossover trial. The studies consisted of a total of 1,029 participants. All studies included male and female participants whose mean ages ranged from 43 to 100 years.

CONCLUSIONS

A positive association was found between medication-induced xerostomia and orofacial pain. No associations were found between salivary flow measurements (hyposalivation) and medication use. Future research should focus on saliva flow measurements, standardized assessment of medication-induced xerostomia, as well as the inclusion of accompanying orofacial pain diagnosis in the medical history to allow for higher level of evidence in establishing reliable predictors of medication-induced oral health damage to facilitate clinical prevention and management.

Factorial structure and measurement invariance of the Chinese version of the Oral Health Impact Profile-14 among clinical populations and non-clinical populations: an evidence for public oral investigations

OBJECTIVE

Oral health-related quality of life (OHRQoL) is a multidimensional concept that is commonly used to examine the impact of oral health status on quality of life. The purpose of this study was to examine the optimal factor model of the Chinese version of the Oral Health Impact Profile (OHIP-14) questionnaire in clinical populations, measurement invariance across clinical status and gender cohorts. This would ensure equal validity of the Chinese version of OHIP-14 in different populations and further support public oral investigations.

METHODS

The Chinese version of OHIP-14 was used to investigate 490 dental patients and 919 college students. Confirmatory factor analysis (CFA), item analysis and reliability, measurement invariance, and the t-test were used for data analyses.

RESULTS

We found that the 7-factor structure had the best-fit index in the sample (CFI = 0.970, TLI = 0.952; SRMR = 0.029, RMSEA = 0.052(0.040,0.063)). The reliability of the scales was satisfactory (Cronbach's α = 0.942). The error variance invariance fitted the data adequately in measurement invariance, indicating that measurement invariance is acceptable both across the clinical and non-clinical populations (∆CFI=-0.017, ∆RMSEA = 0.010) and across genders in the clinical population (∆CFI = 0.000, ∆RMSEA=-0.003). T-test for scores showed that the clinical populations scored significantly higher than the non-clinical populations, as did the overall score (t = 7.046, p < 0.001, d = 0.396), in terms of functional limitation (t = 2.178, p = 0.030, d = 0.125), physical pain (t = 7.880, p < 0.001,d = 0.436), psychological discomfort (t = 8.993, p < 0.001, d = 0.514), physical disability (t = 6.343, p < 0.001, d = 0.358), psychological disability (t = 5.592, p < 0.001, d = 0.315), social disability (t = 5.301, p < 0.001,d = 0.304), social handicap (t = 4.452, p < 0.001, d = 0.253), and that in the non-clinical populations, females scored significantly higher than males, as did in terms of physical pain (t = 3.055, p = 0.002, d = 0.280), psychological discomfort (t = 2.478, p = 0.014, d = 0.222), and psychological disability (t = 2.067, p = 0.039, d = 0.188).

CONCLUSION

This study found that the Chinese version of OHIP-14 has measurement invariance between the clinical and non-clinical populations and across genders in the clinical populations, and can be widely used in OHRQoL assessment for public oral investigations.

Sex-dependent differences in the genomic profile of lingual sensory neurons in naïve and tongue-tumor bearing mice

Mechanisms of sex-dependent orofacial pain are widely understudied. A significant gap in knowledge exists about comprehensive regulation of tissue-specific trigeminal sensory neurons in diseased state of both sexes. Using RNA sequencing of FACS sorted retro-labeled sensory neurons innervating tongue tissue, we determined changes in transcriptomic profiles in males and female mice under naïve as well as tongue-tumor bearing conditions Our data revealed the following interesting findings: (1) FACS sorting obtained higher number of neurons from female trigeminal ganglia (TG) compared to males; (2) Naïve female neurons innervating the tongue expressed immune cell markers such as Csf1R, C1qa and others, that weren't expressed in males. This was validated by Immunohistochemistry. (3) Accordingly, immune cell markers such as Csf1 exclusively sensitized TRPV1 responses in female TG neurons. (4) Male neurons were more tightly regulated than female neurons upon tumor growth and very few differentially expressed genes (DEGs) overlapped between the sexes, (5) Male DEGs contained higher number of transcription factors whereas female DEGs contained higher number of enzymes, cytokines and chemokines. Collectively, this is the first study to characterize the effect of sex as well as of tongue-tumor on global gene expression, pathways and molecular function of tongue-innervating sensory neurons.