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.

Assessment of sleep quality in patients with orofacial pain and headache complaints: A polysomnographic study.

BACKGROUND: Sleep is a physiological function essential for survival, recovery, tissue repair, memory consolidation, and brain function. Pain is also an indispensable aspect of human life. The coexistence of sleep disorders and pain is often described in the literature, yet it is critical to define sleep not only subjectively but also using objective instrumental methods, such as polysomnography, that provide data on sleep quality. OBJECTIVES: The aim of the study was to determine the relationship between orofacial pain (OFP), headache (HA) and sleep quality using subjective and objective sleep quality assessment methods. Additionally, we aimed to explore whether poor sleep quality was related to OFP and HA alone or was influenced by the coexistence of psycho-emotional factors such as depression, anxiety and stress. MATERIAL AND METHODS: A single-night video-polysomnography was performed on patients from the Outpatient Clinic for Temporomandibular Disorders at Wroclaw Medical University, Poland, who had been diagnosed with OFP and HA. Additionally, questionnaires were employed to assess sleep quality, pain, HA, and the psycho-emotional state. RESULTS: There was no statistically significant relationship between the severity of OFP and HA and polysomnographic sleep quality parameters. On the other hand, the quality of sleep as determined by questionnaire studies correlated markedly with the severity of experienced pain. The severity of pain was found to be significantly correlated with depression, anxiety and perceived stress scores. CONCLUSIONS: The psycho-emotional aspects are of critical importance in the perception of OFP and HA. They can be associated with worsened subjective sleep quality, insomnia or daytime sleepiness. Therefore, the treatment of such patients must be preceded by a comprehensive assessment of their psychoemotional state, as anxiety, stress and depression can significantly influence the course of the disease and the response to treatment procedures.

Kinesio Taping as an alternative therapy for limited mandibular mobility with pain in female patients with temporomandibular disorders: A randomized controlled trial.

BACKGROUND: Kinesio Taping (KT) is a non-invasive therapy commonly used in physiotherapy (PT). However, the available data on its effectiveness in patients with symptomatic temporomandibular disorders (TMD) remains scarce and contradictory. OBJECTIVES: The aim of the study was to evaluate the analgesic and myorelaxant effects of KT in TMD patients with limited mandibular mobility. MATERIAL AND METHODS: A single-blind randomized controlled trial was conducted among female patients aged 20-45 years with Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) group Ib, using a parallel group design and equal randomization (1:1). All patients underwent surface electromyography (sEMG) of the masseter muscle (MAS), pain intensity was assessed using a Numeric Rating Scale (NRS), and temporomandibular joint mobility was measured before and after 6 and 12 days of treatment. The Perceived Stress Scale (PSS-10) questionnaire was administered on the first and last days of treatment. Statistical analysis was performed using analysis of variance (ANOVA). Mauchly's sphericity test determined changes over time and between groups for variables with a normal distribution. Bonferroni's correction was used for post hoc multiple comparisons. Variables with a non-normal distribution were analyzed using the nparLD package and multiple comparison post hoc test, while correlations were assessed using Spearman's coefficient. RESULTS: Each treatment had a significant effect on the bioelectrical sEMG parameters (p = 0.05). Kinesio Taping had a superior analgesic effect compared to the controls (p < 0.001). The combination of KT with therapeutic exercise (TE) proved to be a more effective therapy for improving the maximal mouth opening (MMO) and reducing perceived stress than monotherapy (p < 0.001). Minimally significant clinical differences were observed for sEMG, MMO and PSS-10 parameters after both therapies. CONCLUSIONS: Kinesio Taping combined with TE may be considered an effective complementary noninvasive treatment modality for TMD, either as a stand-alone or as part of the therapeutic process in patients experiencing pain and limited mandibular ROM. Additionally, the use of KT and TE was found to have a beneficial effect on perceived stress levels.

Challenged by the jaw - an interview study on patients' experiences of temporomandibular disorders in rheumatic inflammatory diseases.

PURPOSE: Rheumatic inflammatory diseases affecting the temporomandibular joint and the masticatory system (TMD) have been described as painful and limiting. However, the condition is often overlooked in primary care. The objective of this qualitative study was to explore and describe TMD-related experiences and perceptions of persons with rheumatic inflammatory disease, and to put this into a rehabilitation perspective. MATERIALS AND METHODS: Seven participants with rheumatic inflammatory disease and concomitant TMD were interviewed using a semi-structured interview guide. Giorgi's phenomenological method was used for analysis of the material. RESULTS: The general structure of the results after phenomenological reduction indicated that the phenomenon could be described as the process of being challenged by the jaw. Five themes emerged from the analysis; 1. Physical challenges of the jaw and the struggle to retain control, 2. Shame and social challenges, 3. Worrying about the future, frustration, grief, and loss of freedom, 4. Defiance, endurance, and efforts to maintain self-esteem, and 5. Health-care experiences. CONCLUSIONS: TMD in rheumatic inflammatory diseases are complex problems associated with various challenges to the sufferer. An increased awareness of the condition and earlier interventions could reduce both suffering and worsening of the condition.

The connection between the jaw and the rest of the body tends to be neglected.Questions about the jaw should be asked to detect eventual temporomandibular disorder (TMD) at an early stage to prevent worsening of the condition.Patient's experiences of TMD must be considered in the rehabilitation process.Health care providers are important for an earlier, more consistent, and more accessible diagnosis and treatment for this group of people.

Temporomandibular joint rehabilitative approaches for children and adolescents affected by juvenile idiopathic arthritis: A systematic review.

BACKGROUND: Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease of childhood, and temporomandibular joints (TMJs) are involved in 39%-78% of patients. AIM: The aim of this systematic review was to assess the effectiveness of conservative approaches in improving TMJ arthritis in children and adolescents affected by JIA. DESIGN: PubMed, Scopus, and Web of Science were systematically searched from the inception until February 25, 2024, to identify observational studies presenting participants with a diagnosis of JIA affecting the TMJ, rehabilitative approaches for TMJ arthritis as interventions, and clinical or radiological assessment of TMJ arthritis as outcome. RESULTS: Of 478 papers suitable for title/abstract screening, 13 studies were included. The studies evaluated the effectiveness of intra-articular (IA) corticosteroid (CS) injections, IA infliximab injections, arthrocentesis alone or in combination with IACS injections, occlusal splint, functional appliance, and physiotherapy. The effectiveness of IACS injections was shown in eight studies. IA infliximab injections did not appear to significantly improve TMJ arthritis. CONCLUSION: Results of this systematic review suggested that conservative treatments, especially IACS injections, might be effective in improving TMJ arthritis in patients affected by JIA. Further studies with a higher level of evidence and more representative samples should be conducted.

Prevalence of Temporomandibular Disorders (TMD) in Dental Patients at a Specialized Regional Medical Center in Italy.

BACKGROUND AND AIM: This study aimed to evaluate the prevalence of temporomandibular disorders (TMDs) in a sample of general dental patients seeking dental treatments in a northeastern Italian university clinic. MATERIALS AND METHODS: Records of all patients presented for the first time to the dental division of Maggiore Hospital, Italy, between January 1, 2016, and December 31, 2017, were collected. Patients comprised those presenting to the dental clinics for non-TMD complaints, who, upon general examination, were found to have TMD signs and were referred for TMD evaluation. Data were extracted and analyzed, retrospectively. The prevalence of TMDs, age, gender, signs, and symptoms were evaluated. RESULTS: Out of the 18,774 patients studied, 284 had signs of TMD. Women predominance was evident (73%), and patients aged 45-50 were the most frequent sub-population within the TMD population. Clicking was the most commonly present symptom (26.8%), and arthralgia was most commonly diagnosed among this sample (30.7%). A considerable number of patients suffered from muscular disease (myalgia and myofascial pain with 10.1% and 20.7% of the patients, respectively). Significant associations were found among those with myofascial pain on the one hand and degenerative disease and disc displacement with reduction, on the other hand. Furthermore, disc displacement with reduction on one side was associated with displacement without reduction on the other side. CONCLUSION: A considerable number of patients presenting with dental complaints may have asymptomatic TMDs. This highlights the importance of systematic screening of dental patients for TMDs as part of general assessment.

Mirogabalin as a Therapeutic Option for Neuropathic Pain Emerging Post-endodontic Treatment: A Two-case Report.

INTRODUCTION: Occlusal and percussion pain may manifest occasionally following endodontic treatment, influencing retreatment decisions. Two cases of periapical neuropathic pain, classified as post-traumatic trigeminal neuropathic pain according to the International Classification of Orofacial Pain (ICOP), are presented. Although mirogabalin is effective in managing neuropathic pain, there is a lack of clinical reports on its use for occasional post-traumatic trigeminal neuropathic pain after endodontic treatment. These cases highlight clinical symptoms and successful treatment with mirogabalin for post-traumatic trigeminal neuropathic pain after endodontic treatment, providing clinicians a "take-away" lesson for improving patient condition. METHODS: The patients, referred by their primary dentist due to post-endodontic abnormal pain, found no relief with antibiotics or nonsteroidal anti-inflammatory drugs. Although no findings including swelling or periapical radiolucency were observed around the tooth, they experienced occlusal and percussion pain. Local anesthetic testing showed that the pain originated from the peripheral area around the tooth rather than from central sensitization. Dental radiography and cone-beam computed tomography revealed no abnormal findings. Root canal retreatment was performed by a specialist in endodontic treatment. Although endodontic retreatment drastically decreased visual analog scale (VAS) pain score, pain persisted. Based on the ICOP criteria, diseases other than post-traumatic trigeminal neuropathic pain were excluded. Mirogabalin (10 mg/day) was prescribed once daily before bedtime. RESULTS: VAS scores gradually and drastically decreased 2 weeks after mirogabalin therapy. Several months later, no recurrence of post-endodontic pain was observed after tapering off and discontinuing mirogabalin. CONCLUSIONS: These findings suggest the possibility of a new treatment method for post-traumatic trigeminal neuropathic pain after endodontic treatment.

Reappraising the psychosomatic approach in the study of "chronic orofacial pain": looking for the essential nature of these intractable conditions.

As burning mouth syndrome (BMS) and atypical odontalgia (AO) continue to remain complex in terms of pathophysiology and lack explicit treatment protocol, clinicians are left searching for appropriate solutions. Oversimplification solves nothing about what bothers us in clinical situations with BMS or AO. It is important to treat a complicated phenomenon as complex. We should keep careful observations and fact-finding based on a pragmatic approach toward drug selection and prescription with regular follow-up. We also need to assess the long-term prognosis of treatment with a meticulous selection of sample size and characteristics. Further investigation of BMS and AO from a psychosomatic perspective has the potential to provide new insight into the interface between brain function and "chronic orofacial pain."

Assessment of orofacial nociceptive behaviors of mice with the sheltering tube method: Oxaliplatin-induced mechanical and cold allodynia in orofacial regions.

Preclinical studies on pathological pain rely on the von Frey test to examine changes in mechanical thresholds and the acetone spray test to determine alterations in cold sensitivity in rodents. These tests are typically conducted on rodent hindpaws, where animals with pathological pain show reliable nocifensive responses to von Frey filaments and acetone drops applied to the hindpaws. Pathological pain in orofacial regions is also an important clinical problem and has been investigated with rodents. However, performing the von Frey and acetone spray tests in the orofacial region has been challenging, largely due to the high mobility of the head of testing animals. To solve this problem, we implemented a sheltering tube method to assess orofacial nociception in mice. In experiments, mice were sheltered in elevated tubes, where they were quickly accommodated because the tubes provided safe shelters for mice. Examiners could reliably apply mechanical stimuli with von Frey filament, cold stimuli with acetone spray, and light stimuli with a laser beam to the orofacial regions. We validated this method in Nav1.8-ChR2 mice treated with oxaliplatin that induced peripheral neuropathy. Using the von Frey test, orofacial response frequencies and nociceptive response scores were significantly increased in Nav1.8-ChR2 mice treated with oxaliplatin. In the acetone spray test, the duration of orofacial responses was significantly prolonged in oxaliplatin-treated mice. The response frequencies to laser light stimulation were significantly increased in Nav1.8-ChR2 mice treated with oxaliplatin. Our sheltering tube method allows us to reliably perform the von Frey, acetone spray, and optogenetic tests in orofacial regions to investigate orofacial pain.

Burning measure for burning mouth syndrome: a systematic review.

This current systematic review aimed to evaluate the current evidence on the effect of topical capsaicin application to alleviate symptoms related to burning mouth syndrome (BMS). PubMed, Ovid SP, and Cochrane were searched from 1980 to 2022 to identify relevant literature. A total of 942 titles (PubMed, 84; Ovid SP, 839; Cochrane, 19) was retrieved, of which 936 were excluded based on the title and abstract. A total of 11 studies were further evaluated for full text analysis, of which 7 were excluded. As a result, 4 articles were included for qualitative synthesis of data. Capsaicin as a mouthwash can have potential application in the treatment of symptoms related to burning mouth. The quality of available studies is moderate to low, and a well-designed randomized multicentric study comparing capsaicin with other active agents is planned to obtain more definitive conclusions.

The role of voltage-gated calcium channel α2δ-1 in the occurrence and development in myofascial orofacial pain.

Patients who suffer from myofascial orofacial pain could affect their quality of life deeply. The pathogenesis of pain is still unclear. Our objective was to assess Whether Voltage-gated calcium channel α2δ-1(Cavα2δ-1) is related to myofascial orofacial pain. Rats were divided into the masseter tendon ligation group and the sham group. Compared with the sham group, the mechanical pain threshold of the masseter tendon ligation group was reduced on the 4th, 7th, 10th and 14th day after operation(P < 0.05). On the 14th day after operation, Cavα2δ-1 mRNA expression levels in trigeminal ganglion (TG) and the trigeminal spinal subnucleus caudalis and C1-C2 spinal cervical dorsal horn (Vc/C2) of the masseter tendon ligation group were increased (PTG=0.021, PVc/C2=0.012). Rats were divided into three groups. On the 4th day after ligating the superficial tendon of the left masseter muscle of the rats, 10 ul Cavα2δ-1 antisense oligonucleotide, 10 ul Cavα2δ-1 mismatched oligonucleotides and 10 ul normal saline was separately injected into the left masseter muscle of rats in Cavα2δ-1 antisense oligonucleotide group, Cavα2δ-1 mismatched oligonucleotides group and normal saline control group twice a day for 4 days. The mechanical pain threshold of the Cavα2δ-1 antisense oligonucleotides group was higher than Cavα2δ-1 mismatched oligonucleotides group on the 7th and 10th day after operation (P < 0.01). After PC12 cells were treated with lipopolysaccharide, Cavα2δ-1 mRNA expression level increased (P < 0.001). Cavα2δ-1 may be involved in the occurrence and development in myofascial orofacial pain.

The Contribution of Sleep Quality and Psychological Factors to the Experience of Within-Day Pain Fluctuations Among Individuals With Temporomandibular Disorders.

We assessed the impact of day-to-day sleep quality and psychological variables (catastrophizing, negative affect, and positive affect) to within-day pain fluctuations in 42 females with painful temporomandibular disorders (TMD) using electronic diaries. More specifically, we examined the contribution of these variables to the likelihood of experiencing pain exacerbations defined as 1) an increase of 20 points (or more) in pain intensity on a 0 to 100 visual analog scale from morning to evening, and/or 2) a transition from mild-to-moderate pain over the course of the day; and pain decreases defined as 3) a decrease of 20 points (or more) in pain intensity (visual analog scale) from morning to evening, and/or 4) a reduction from moderate-to-mild pain over the day. The results indicated significantly main effects of sleep on both pain exacerbation outcomes (both P's < .05), indicating that nights with better sleep quality were less likely to be followed by clinically meaningful pain exacerbations on the next day. The results also indicated that days characterized by higher levels of catastrophizing were associated with a greater likelihood of pain exacerbations on the same day (both P's < .05). Daily catastrophizing was the only variable significantly associated with within-day pain decrease indices (both P's < .05). None of the other variables were associated with these outcomes (all P's > .05). These results underscore the importance of addressing patients' sleep quality and psychological states in the management of painful TMD. PERSPECTIVES: These findings highlight the significance of sleep quality and pain catastrophizing in the experience of within-day pain fluctuations among individuals with TMD. Addressing these components through tailored interventions may help to alleviate the impact of pain fluctuations and enhance the overall well-being of TMD patients.

Neuropathic pain in cats: Mechanisms and multimodal management.

PRACTICAL RELEVANCE: Chronic pain is a significant welfare concern in cats, and neuropathic pain, which arises from aberrant processing of sensory signals within the nervous system, is a subcategory of this type of pain. To comprehend this condition and how multimodal pharmacotherapy plays a central role in alleviating discomfort, it is crucial to delve into the anatomy of nociception and pain perception. In addition, there is an intricate interplay between emotional health and chronic pain in cats, and understanding and addressing the emotional factors that contribute to pain perception, and vice versa, is essential for comprehensive care.Clinical approach:Neuropathic pain is suspected if there is abnormal sensation in the area of the distribution of pain, together with a positive response to trial treatment with drugs effective for neuropathic pain. Ideally, this clinical suspicion would be supported by confirmation of a lesion at this neurolocalisation using diagnostic modalities such as MRI and neuroelectrophysiology. Alternatively, there may be a history of known trauma at that site. A variety of therapies, including analgesic, anti-inflammatory and adjuvant drugs, and neuromodulation (eg, TENS or acupuncture), can be employed to address different facets of pain pathways.Aim:This review article, aimed at primary care/ general practitioners, focuses on the identification and management of neuropathic pain in cats. Three case vignettes are included and a structured treatment algorithm is presented to guide veterinarians in tailoring interventions.Evidence base:The review draws on current literature, where available, along with the author's extensive experience and research.

Trigeminal somatosensation in the temporomandibular joint and associated disorders.

The temporomandibular joint (TMJ) consists of bone, cartilage, ligaments, and associated masticatory muscles and tendons that coordinate to enable mastication in mammals. The TMJ is innervated by the trigeminal nerve (CNV), containing axons of motor and somatosensory neurons. Somatosensation includes touch, temperature, proprioception, and pain that enables mammals to recognize and react to stimuli for survival. The somatosensory innervation of the TMJ remains poorly defined. Disorders of the TMJ (TMD) are of diverse etiology and presentation. Some known symptoms associated with TMD include facial, shoulder, or neck pain, jaw popping or clicking, headaches, toothaches, and tinnitus. Acute or chronic pain in TMD stems from the activation of somatosensory nociceptors. Treatment of TMD may involve over- the-counter and prescription medication, nonsurgical treatments, and surgical treatments. In many cases, treatment achieves only a temporary relief of symptoms including pain. We suggest that defining the sensory innervation of the temporomandibular joint and its associated tissues with a specific focus on the contribution of peripheral innervation to the development of chronic pain could provide insights into the origins of joint pain and facilitate the development of improved analgesics and treatments for TMD.

Temporomandibular Disorders, Bruxism and Headaches.

Temporomandibular disorders (TMDs) and headache disorders are highly prevalent in the population. TMDs can present headache symptoms as a secondary headache and, in addition, be comorbid with primary headache disorders. This overlap has significant clinical implications for which it is essential for the physician to be aware, and they should screen for the potential presence of TMDs in a headache patient. Bruxism is a parafunctional behavior also prevalent in the population which has a role in TMDs and may influence headache symptomatology, but it is still necessary to clarify this relationship.

Other Secondary Headaches: Odontogenic Pain and Other Painful Orofacial Conditions.

This article discusses extremely common odontogenic pain conditions, which may occasionally present to the neurology clinic mimicking headache, and other uncommon orofacial pain conditions, which may do the same. Typical presentations, investigative strategies, and management are discussed, as well as highlighting key diagnostic criteria and the importance of involving oral or dental specialists where diagnostic uncertainty exists.

RNA sequencing of the thalamus and rostral ventral medulla in rats with chronic orofacial pain.

Diagnosing and treating chronic orofacial pain is challenging due to its complex structure and limited understanding of its causes and mechanisms. In this study, we used RNA sequencing to identify differentially expressed genes (DEGs) in the rostral ventral medulla (RVM) and thalamus of rats with persistent orofacial pain, aiming to explore its development. DEGs were functionally analyzed using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Results showed a significant association between immune response and pain in this model. Key DEG mRNA expression trends were further validated using real-time quantitative polymerase chain reaction (RT-PCR), confirming their crucial roles in chronic orofacial pain. After injecting complete Freund's adjuvant (CFA) into the bilateral temporomandibular joint cavity for 14 days, we observed 293 upregulated genes and 14 downregulated genes in the RVM, and 1086 upregulated genes and 37 downregulated genes in the thalamus. Furthermore, we identified 27 common DEGs with altered expression (upregulation) in both the thalamus and RVM, including Cd74, C3, Cxcl13, C1qb, Itgal, Fcgr2b, C5ar1, and Tlr2, which are pain-associated genes. Protein-protein interaction (PPI) analysis using Cytoscape revealed the involvement of Toll-like receptors, complement system, differentiation clusters, and antigen presentation-related proteins in the interaction between the thalamus and RVM. The results of this study show that the immune system seems to have a more significant influence on chronic orofacial pain. There may be direct or indirect influence between the thalamus and RVM, which may participate in the regulation of chronic orofacial pain.

Visual psychosocial profiling of Chinese temporomandibular disorder pain patients and correlations with somatosensory function.

BACKGROUND: Psychosocial function of Chinese temporomandibular disorders (TMD) pain patients and the correlation with somatosensory function has not been sufficiently studied. OBJECTIVE: The study aims at assessing the psychosocial function of Chinese TMD pain patients by visualisation method and evaluating the correlations with somatosensory function quantitatively. METHODS: The Symptom Checklist 90 (SCL-90) questionnaire and standardised quantitative sensory testing (QST) were administered to 70 Chinese TMD pain patients and age- and gender-matched healthy controls (HCs). Of these, 40 TMD arthralgia patients received QST before and after medication. Psychosocial and somatosensory parameters were transformed into standardised scores. Differences within groups were assessed through t tests. Correlations between psychosocial and somatosensory profiles were explored through correlation analyses with Bonferroni correction for multiple comparisons. RESULTS: 100% of the Chinese TMD pain patients exhibited psychosocial distress in contrast to HCs. Anger and hostility showed negative correlation with the thermal nonnociceptive parameter (thermal sensory limen, p =.002) and nociceptive parameters (cold pain threshold and pain pressure threshold, p<.001). Correlation analysis indicated that cold detection threshold was negatively correlated with somatization and mechanical pain sensitivity had a negative correlation with anger and hostility through medical treatment (p <.001). CONCLUSIONS: Visual psychosocial profiles provided an easy overview of psychosocial function in Chinese TMD pain patients. Anger and hostility was associated with increased thermal nonnociceptive and nociceptive sensitivity to stimuli. Psychosocial distress might be negatively associated with TMD treatment response which indicated a possible need for psychological intervention during treatment.

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-1ß, 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-1ß, 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.

Saliva and tongue microbiota in burning mouth syndrome: An exploratory study of potential roles.

OBJECTIVES: Burning mouth syndrome (BMS) is a chronic orofacial pain disorder with unclear etiology, in which the tongue is most commonly affected. This study aims to provide implication of the possible relationship between oral microbiota and the pathogenesis of BMS. MATERIALS AND METHODS: Saliva and tongue swabs of 15 primary BMS patients and 10 healthy controls were collected and assessed by 16S rRNA gene amplicon sequencing. The microbiota compositions were compared and bioinformatic analysis was conducted. RESULTS: Differences in microbiota compositions between BMS patients and healthy controls were revealed in both saliva and tongue samples. In saliva, Streptococcus, Rothia, and Neisseria were the predominant genus at the taxonomic level in BMS patients. In tongue samples, Prevotella, Streptococcus, and Neisseria were the dominant genus at the taxonomic level in BMS patients. LEfSe analysis and linear discriminant analysis score showed that Actinobacteria were the predominant phylum in saliva, and Selenomonas were enriched in the dorsum of the tongue of BMS patients. CONCLUSIONS: This study for the first-time reported saliva and tongue microbiota profiles were distinguished from that of healthy controls, indicating a necessity for further research on the possible relationship between oral microbes and the pathogenesis of BMS.