Treatment of temporomandibular joint internal derangement using MESNA injection.

INTRODUCTION: The development of temporomandibular disorders specifically emphasizes the biochemical changes occurring in the synovial fluid at different stages of temporomandibular joint disease. Research has indicated that inflammation may be a primary reason behind the pain and dysfunction in temporomandibular joint diseases. Since its clearance several years ago, MESNA (sodium 2-mercaptoethanesulfonate) has been used in various formulations as a mucolytic drug in the respiratory domain. It operates by disrupting the disulfide bonds present between polypeptide chains within mucus. MESNA exhibits minimal tissue distribution, with the material being swiftly and thoroughly eliminated via the kidneys. OBJECTIVES: To assess the efficacy of injecting MESNA directly into the Temporomandibular Joint to treat internal derangement. MATERIALS AND METHODS: A randomized clinical trial was conducted on sixty patients who exhibited non-responsiveness to conventional treatment and were diagnosed with TMJ anterior disc displacement with reduction. The patients were chosen from the outpatient clinic of the Oral and Maxillofacial Surgery Department at Tanta University Faculty of Dentistry. Two equal groups of patients were randomly assigned to each other. Group I (Mesna group) received intra-articular injection with MESNA solution. Group II (Standard group) received arthrocentesis with lactated ringer solution followed by injection of Hyaluronic Acid (HA). The data was gathered by functional examinations such as maximum interincisal opening (MIO) and clicking. A Visual Analogue Scale (VAS) assessed pain severity before and after treatments. RESULTS: Both MESNA and HA showed significant improvement up to six months of the follow-up compared to preoperative status, as evidenced by better mouth opening, lateral excursion, lower clicking, and reduced pain score in patients with TMDs. MESNA showed significant improvement during follow-up compared to HA. CONCLUSION: Compared to HA, MESNA showed a more noticeable improvement during the follow-up period.

Orofacial antinociceptive activity of codeine-associated geraniol in mice: a controlled triple-blind study.

This is a nonclinical, controlled, and triple-blind study to investigate the effects of codeine-associated geraniol on the modulation of orofacial nociception and its potential central nervous system depressing effect in an animal model. The orofacial antinociceptive activity of geraniol in combination with codeine was assessed through the following tests: (i) formalin-induced pain, (ii) glutamate-induced pain, and (iii) capsaicin-induced pain. Six animals were equally distributed into six groups and received the following treatments, given intraperitoneally (i.p.) 30 minutes before the experiments: a) geraniol/codeine 50/30 mg/kg; b) geraniol/codeine 50/15 mg/kg; c) geraniol/codeine 50/7.5 mg/kg; d) geraniol 50 mg/kg; e) codeine 30 mg/kg (positive control); or f) 0.9% sodium chloride (negative control). We performed pain behavior analysis after the injection of formalin (20 µL, 20%), glutamate (20 µL, 25 µM), and capsaicin (20 µL, 2.5 µg) into the paranasal region. Rubbing time of the paranasal region by the hind or front paw was used as a parameter. In the neurogenic phase of the formalin test, the geraniol/codeine at 50/7.5 mg/kg was able to promote the maximum antinociceptive effect, reducing nociception by 71.9% (p < 0.0001). In the inflammatory phase of the formalin test, geraniol/codeine at 50/30 mg/kg significantly reduced orofacial nociception (p < 0.005). In the glutamate test, geraniol/codeine at 50/30 mg/kg reduced the rubbing time by 54.2% and reduced nociception in the capsaicin test by 66.7% (p < 0.005). Geraniol alone or in combination does not promote nonspecific depressing effects on the central nervous system. Based on our findings, we suggest the possible synergy between geraniol and codeine in the modulation of orofacial pain.

Impact of streptozotocin-induced diabetes on experimental masseter pain in rats.

This study aimed to assess the influence of streptozotocin (STZ)-induced diabetes on the nociceptive behavior evoked by the injection of hypertonic saline (HS) into the masseter muscle of rats. Forty male rats were equally divided into four groups: a) isotonic saline control, which received 0.9% isotonic saline (IS), (Ctrl-IS); b) hypertonic saline control, which received 5% HS (Ctrl-HS); c) STZ-induced diabetic, which received IS, (STZ-IS); d) STZ-induced diabetic, which received HS (STZ-HS). Experimental diabetes was induced by a single intraperitoneal injection of STZ at dose of 60 mg/kg dissolved in 0.1 M citrate buffer, and 100 µL of HS or IS were injected into the left masseter to measure the nociceptive behavior. Later on, muscle RNA was extracted to measure the relative expression of the following cytokines: cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF-α), and interleukins (IL)-1ß, -2, -6, and -10. One-way analysis of variance (ANOVA) was applied to the data (p < 0.050). We observed a main effect of group on the nociceptive response (ANOVA: F = 11.60, p < 0.001), where the Ctrl-HS group presented the highest response (p < 0.001). However, nociceptive response was similar among the Ctrl-IS, STZ-IS, and STZ-HS group (p > 0.050). In addition, the highest relative gene expression of TNF-α and IL-6 was found in the masseter of control rats following experimental muscle pain (p < 0.050). In conclusion, the loss of somatosensory function can be observed in deep orofacial tissues of STZ-induced diabetic rats.

[28-year-old male patient with headaches on the left side and facial pain]. / 28-jähriger Patient mit in den Kiefer ausstrahlenden ­Kopfschmerzen temporal links.

INTRODUCTION: A 28-year-old male suffers for two weeks from new-onset very severe headache located on his left temple radiating to his jaw. He also complains about left sided retroorbital pain and chewing aggravated symptoms. In addition, nausea and emesis in the mornings during the past six months were reported. Clinical examination revealed tender swelling over the left temple, but laboratory results showed no signs of inflammation, normal electrolytes, kidney and liver values. A CT-scan revealed a circumscriptive osteolytic lesion in the left os temporale.

Clinical profile in relation to age and gender of patients with temporomandibular disorders: a retrospective study.

BACKGROUND: The present study is to evaluate the clinical characteristics of patients with temporomandibular disorders (TMD). METHODS: A total of 3362 TMD patients were included. Each participant had complete medical records according to the diagnostic criteria for temporomandibular disorders (DC/TMD). The clinical characteristics including symptoms and signs in relation to age and gender were analyzed. RESULTS: The mean age of the patients seeking care was 29.89 ± 13.73Y, and 68.6% of patients were aged 16-35 years. The female-to-male ratio of patients was 2.2: 1, and the average age of males was significantly lower than that of females. The prevalence of clicking symptoms decreased with age, while the prevalence of pain symptoms and limitations in jaw movement increased with age. Females were more likely to have limitations in jaw movement than males. Among the patients with pain, the average visual analogue scale (VAS) was 2.96 ± 1.23. The average VAS score of acute TMD patients (≤ 3 months) was significantly higher than that of chronic TMD patients (> 3 months). CONCLUSIONS: The majority of TMD patients seeking care were young people. The number and average age of female patients was higher than the males. Female patients were more likely to have limitations in jaw movement than males.

Muscle oxygenation and pain in different types of temporomandibular disorders.

OBJECTIVES: Studies exploring variations in peripheral muscle oxygenation and pressure pain thresholds (PPT) of masticatory muscles in individuals with Temporomandibular Disorders (TMDs) are limited. The purpose of this study was to compare variations in peripheral oxygenation of the masseter muscle; PPT of the masseter and temporal muscles and correlate peripheral muscle oxygenation and PPT of the masseter muscle in individuals with different types of TMDs. MATERIALS AND METHODS: Cross-sectional study involving 116 participants classified into three groups: muscle group (MG, n = 32), joint group (JG, n = 30) and muscle-joint group (MJG, n = 54). Individuals aged 26.97 ± 6.93, 68.97% female, 31,03% males were included. All participants were evaluated using the Diagnostic Criteria for Temporomandibular Disorders, Near-infrared spectroscopy (NIRS) for peripheral muscle oxygenation and pressure algometer for PPT. RESULTS: There was no difference in masseter muscle oxygenation among groups. In the masseter muscle, a weakly positive correlation was observed between PPT and variation in tissue saturation index in the MG (rho = 0.365) and JG (rho = 0.317). In addition, the MJG expressed lower PPT (p = 0.004) than JG, demonstrating that MJG had more pain in this muscle. CONCLUSIONS: MJG have lower PPT in the masseter muscle. Although the PPT is dependent on the type of TMDs, the correlation between PPT and oxygenation is weak. All TMDs groups evaluated (MG, JG, MJG) showed hemodynamic similarities of the masseter muscle. CLINICAL RELEVANCE: Understanding pain thresholds and the hemodynamic behavior of the masticatory muscles contributes to a more assertive physiotherapeutic assessment in TMDs, serving as a basis for careful and individualized interventions.

Contribution of inwardly rectifying potassium channel 4.1 in orofacial neuropathic pain: Regulation of pannexin 3 via the reactive oxygen species-activated P38 MAPK signal pathway.

The involvement of inwardly rectifying potassium channel 4.1 (Kir4.1) in neuropathic pain has been established. However, there is limited understanding of the downstream mechanism through which Kir4.1 contributes to orofacial neuropathic pain. The objective of this study was to examine the regulation of Kir4.1 on the expression of pannexin 3 (Panx3) in the trigeminal ganglion (TG) and the underlying mechanism in the context of orofacial neuropathic pain caused by chronic constriction injury of the infraorbital nerve (CCI-ION). The study observed a significant increase in Panx3 expression in the TG of mice with CCI-ION. Inhibition of Panx3 in the TG of CCI-ION mice resulted in alleviation of orofacial mechanical allodynia. Furthermore, conditional knockdown (CKD) of Kir4.1 in the TG of both male and female mice led to mechanical allodynia and upregulation of Panx3 expression. Conversely, overexpression of Kir4.1 decreased Panx3 levels in the TG and relieved mechanical allodynia in CCI-ION mice. In addition, silencing Kir4.1 in satellite glial cells (SGCs) decreased Panx3 expression and increased the phosphorylation of P38 MAPK. Moreover, silencing Kir4.1 in SGCs increased the levels of reactive oxygen species (ROS). The elevated phosphorylation of P38 MAPK resulting from Kir4.1 silencing was inhibited by using a superoxide scavenger known as the tempol. Silencing Panx3 in the TG in vivo attenuated the mechanical allodynia caused by Kir4.1 CKD. In conclusion, these findings suggest that the reduction of Kir4.1 promotes the expression of Panx3 by activating the ROS-P38 MAPK signalling pathway, thus contributing to the development of orofacial neuropathic pain.

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.

Cytoarchitecture and intercellular interactions in the trigeminal ganglion: Associations with neuropathic pain in the orofacial region.

BACKGROUND: Disorders of the trigeminal nerve, a sensory nerve of the orofacial region, often lead to complications in dental practice, including neuropathic pain, allodynia, and ectopic pain. Management of these complications requires an understanding of the cytoarchitecture of the trigeminal ganglion, where the cell bodies of the trigeminal nerve are located, and the mechanisms of cell-cell interactions. HIGHLIGHTS: In the trigeminal ganglion, ganglion, satellite, Schwann, and immune cells coexist and interact. Cell-cell interactions are complex and occur through direct contact via gap junctions or through mediators such as adenosine triphosphate, nitric oxide, peptides, and cytokines. Interactions between the nervous and immune systems within the trigeminal ganglion may have neuroprotective effects during nerve injury or may exacerbate inflammation and produce chronic pain. Under pathological conditions of the trigeminal nerve, cell-cell interactions can cause allodynia and ectopic pain. Although cell-cell interactions that occur via mediators can act at some distance, they are more effective when the cells are close together. Therefore, information on the three-dimensional topography of trigeminal ganglion cells is essential for understanding the pathophysiology of ectopic pain. CONCLUSIONS: A three-dimensional map of the somatotopic localization of trigeminal ganglion neurons revealed that ganglion cells innervating distant orofacial regions are often apposed to each other, interacting with and potentially contributing to ectopic pain. Elucidation of the complex network of mediators and their receptors responsible for intercellular communication within the trigeminal ganglion is essential for understanding ectopic pain.

Non-neuronal cells act as crucial players in neuropathic orofacial pain.

BACKGROUND: Following peripheral nerve damage, various non-neuronal cells are activated, triggering accumulation in the peripheral and central nervous systems, and communicate with neurons. Evidence suggest that neuronal and non-neuronal cell communication is a critical mechanism of neuropathic pain; however, its detailed mechanisms in contributing to neuropathic orofacial pain development remain unclear. HIGHLIGHT: Neuronal and non-neuronal cell communication in the trigeminal ganglion (TG) is believed to cause neuronal hyperactivation following trigeminal nerve damage, resulting in neuropathic orofacial pain. Trigeminal nerve damage activates and accumulates non-neuronal cells, such as satellite cells and macrophages in the TG and microglia, astrocytes, and oligodendrocytes in the trigeminal spinal subnucleus caudalis (Vc) and upper cervical spinal cord (C1-C2). These non-neuronal cells release various molecules, contributing to the hyperactivation of TG, Vc, and C1-C2 nociceptive neurons. These hyperactive nociceptive neurons release molecules that enhance non-neuronal cell activation. This neuron and non-neuronal cell crosstalk causes hyperactivation of nociceptive neurons in the TG, Vc, and C1-C2. Here, we addressed previous and recent data on the contribution of neuronal and non-neuronal cell communication and its involvement in neuropathic orofacial pain development. CONCLUSION: Previous and recent data suggest that neuronal and non-neuronal cell communication in the TG, Vc, and C1-C2 is a key mechanism that causes neuropathic orofacial pain associated with trigeminal nerve damage.

High prevalence of orofacial pain in juvenile fibromyalgia as detected by a novel tool specifically devised for children and adolescents.

OBJECTIVES: To examine the prevalence of temporomandibular disorders (TMD) in patients with juvenile fibromyalgia syndrome (JFS) and identify TMD characteristics specifically associated to JFS. METHODS: Signs and symptoms of TMD were assessed using a novel clinical tool specifically devised for children that consists of: 1. a self-report multiple-choice questionnaire; 2. a protocol for the clinical examination of the orofacial region. Multivariate logistic regression model was used to identify TMD features associated with JFS. RESULTS: Thirty JFS patients (median age 15.5 years) and 45 healthy controls (median age 15.0 years) were included in this cross-sectional study. Orofacial pain was reported by 26 of 30 JFS patients (86.7%) and by 3 of 45 controls (6.7%; p<0.001). Pain on TMJ palpation was present in 18 of 30 JFS patients (60%) and in 5 of 45 controls (11.1%; p<0.001). Median values of maximum spontaneous mouth opening, voluntary active opening and assisted passive opening were significantly higher in JFS patients than in controls. On multiple regression analysis spontaneous orofacial pain (OR: 21.0; p=0.005), diffuse tenderness on palpation of the masticatory muscles (OR: 14.9; p=0.026) and TMJ hypermobility (OR 1.42; p=0.008) were independently associated with JFS. CONCLUSIONS: The high prevalence of TMD in JFS highlights the need for a broader interdisciplinary evaluation of JFS patients. TMJ hypermobility, in addition to orofacial and masticatory muscle pain, is an important clue for the diagnosis of TMD in adolescents with JFS. Elucidating the link between these disorders will advance individualised management and improve treatment efficacy.

Does combining oro-facial manual therapy with bruxism neuroscience education affect pain and function in cases of awake bruxism? A pilot study.

BACKGROUND: Although awake bruxism is associated with temporomandibular disorder (TMD) as well as head and neck pain, the effects of physical therapy and bruxism education to address these factors have not been investigated. OBJECTIVE: The aim of this study was to evaluate the effects of oro-facial manual therapy and bruxism neuroscience education (BNE) on awake bruxism over a 3-week period with an open-ended follow-up questionnaire after 3 months. METHODS: Subjects (n = 28) were randomly allocated to one of two groups, an intervention group and a control group. Data regarding disability, function and pain were collected pre- and post-assessment, with all measures administered in a single-blind fashion. Participants in both groups received six treatment sessions during this period. In addition to manual therapy, participants were provided with information on the neurophysiological mechanisms of bruxism and contributing factors. Individual behavioural guidelines and daily exercises were determined in consultation with the therapist. An introduction to a bruxism specific app (Brux.App) was also provided, which all participants used as an adjunct to their treatment. RESULTS: The intervention group demonstrated notable improvement as indicated by their scores in the Neck Disability Index (NDI) (p = .008), Pain Disability Index (PDI) (p = .007) and Jaw Disability List (JDL) (p = .03). Furthermore, clinical assessments of the temporomandibular joint (TMJ) revealed a significant progress in terms of mouth opening (p = .03) and lateral jaw movement (laterotrusion) (p = .03). The mechanical pain threshold (PTT) of both the masseter (p = .02) and temporalis muscle (p = .05) also showed significant improvement. At 3-month follow-up, the questionnaire revealed that the majority of the intervention group (13/15, 87%) reported a benefit from the treatment. CONCLUSION: The reduction in pain and disability together with improvement in function and increased coping suggest a potential modification of awake bruxism through specialised musculoskeletal intervention and BNE tailored to the individual patient.

Telediagnosis as an effective tool for assessment temporomandibular disorders.

BACKGROUND: The use of communication technologies has allowed a substantial improvement in telediagnosis. OBJECTIVES: To evaluate the feasibility and diagnostic agreement of synchronous teleconsultation compared to physical standard examination for temporomandibular disorders (TMD) and orofacial pain. METHODS: Sixty-one patients (50 women, 11 men) with a mean age of 46.07 years referred to the Orofacial Pain Ambulatory Service (SAMDOF -UFPR) were evaluated remotely. They were then examined in person by another evaluator, blinded for the first evaluation. Data on the experience and level of satisfaction with the teleconsultation were also collected. RESULTS: For each type and subtype of TMD, diagnostic agreement values, sensitivity, specificity, positive predictive values and negative predictive values were calculated with a 95% confidence interval. 'Almost perfect' agreement was found for Myalgia (k = 0.915), Arthralgia (k = 0.863), disc displacement without reduction without limited opening (k = 0.955) and no TMD (k = 1.00). 'Substantial' agreement for the subtypes headache attributed to TMD (k = 0.761), disc displacement without reduction with limited opening (k = 0.659) and subluxation (k = 7.82). The diagnoses of local myalgia (k = 0.573), myofascial pain with referral (k = 0.524) and disc displacement with reduction (k = 0.563) obtained 'moderate' agreement. Degenerative joint disease (k = 0.170) and disc displacement with reduction with intermittent locking (k = 0.000) obtained 'weak' and 'no agreement', respectively. More than 90% of the participants were satisfied and reported no discomfort during the assessment, agreeing to participate in another teleconsultation. CONCLUSION: Synchronous teleconsultation proved to be feasible and presented adequate diagnostic agreement for the main painful TMDs, especially for the diagnosis of myalgia and arthralgia. This format was also well accepted among patients.

Characteristics of painful temporomandibular disorders and their influence on jaw functional limitation and oral health-related quality of life.

BACKGROUND: There is limited knowledge about the impact of painful temporomandibular disorders (TMDs) and pain characteristics on jaw functional limitation and oral health-related quality of life (OHRQoL) in TMD patients. OBJECTIVES: The influence of painful TMDs and pain characteristics on jaw functional limitation and OHRQoL was investigated. Inter-relationships between limitation in jaw function and various OHRQoL domains, along with facial pain attributes predicting impaired jaw function and diminished OHRQoL were also examined. METHODS: TMD patients were recruited from a university-based hospital. A comprehensive questionnaire comprising demographic variables, the DC/TMD Symptom Questionnaire, Graded Chronic Pain Scale, Jaw Functional Limitation Scale-8 (JFLS-8) and Oral Health Impact Profile-TMD (OHIP-TMD) was administered. Participants underwent a protocolized physical examination, and TMD diagnoses were determined utilising the DC/TMD algorithms. Participants were subsequently stratified into intra-articular/pain-related/combined TMD groups, as well as no TMD pain, acute/chronic pain and low/high-intensity pain groups. Data were assessed using non-parametric and hierarchical linear regression analyses (α = .05). RESULTS: The final sample consisted of 280 participants (mean age 31.2 (SD 11.8) years; 79.3% women). Significant differences in pain characteristics, JFLS-8, and global OHIP scores were observed across the various TMD subtypes, pain chronicity and pain intensity categories. Pain intensity and pain-related interference exhibited moderate correlations with JFLS-8 and global OHIP scores (rs = 0.53-0.60). Moderate associations were also noted between JFLS-8 and global OHIP, as well as most OHIP domains (rs = 0.42-0.64). Both jaw functional limitation and OHRQoL were predicted by sex, pain intensity and pain-related interference. CONCLUSIONS: Sex, pain intensity and pain-related interference are key determinants for both impaired jaw function and diminished OHRQoL, with pain-related interference exerting a more pronounced effect.

Can temporomandibular disorder symptoms and headaches be prevented in 13- to 15-year-old girls by information provided in a school setting?

OBJECTIVE: Temporomandibular disorders (TMD) may develop, especially among girls, during the adolescence period. The aim of this study was to study if information and advice in a school setting could prevent development of TMD symptoms and headaches during the early teenage period. METHODS: Thirteen-year-old girls, at 19 upper elementary schools were invited to participate in a study with structured information about the jaw system, TMD symptoms and risk factors, as well as advice how to manage risk factor and TMD. Six hundred and fifty-one girls enrolled, of which 507 girls were followed for 2-2.5 years. Half received information on three occasions (cases), and the other half served as controls. Included in the analysis of incidence of TMD symptoms were those without frequently occurring TMD symptoms (not including headaches) at baseline (n = 396) and included in the analysis of incidence of headaches were those without frequent headaches at baseline (n = 297). RESULT: The 2-year incidence of TMD symptoms was significantly lower in the information cohort (19%) compared to the controls (28%) (p = .03). The 2-year incidence of headaches was lower among those who were allocated to information (30%) compared to controls (40%), but the difference was not statistically significant (p = .099). Cases who had headaches at baseline reported a significantly lower prevalence at follow-up compared to controls (p = .03). CONCLUSION: Standardized information in school settings can prevent development of TMD symptoms and headaches among young girls.

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.

Botulinum toxin type A is a potential therapeutic drug for chronic orofacial pain.

BACKGROUND: Botulinum toxin type A (BTX-A), produced by the gram-positive anaerobic bacterium Clostridium botulinum, acts by cleaving synaptosome-associated protein-25 (SNAP-25), an essential component of the presynaptic neuronal membrane that is necessary for fusion with the membrane proteins of neurotransmitter-containing vesicles. Recent studies have highlighted the efficacy of BTX-A in treating chronic pain conditions, including lower back pain, chronic neck pain, neuropathic pain, and trigeminal neuralgia, particularly when patients are unresponsive to traditional painkillers. This review focuses on the analgesic effects of BTX-A in various chronic pain conditions, with a particular emphasis on the orofacial region. HIGHLIGHT: This review focuses on the mechanisms by which BTX-A induces analgesia in patients with inflammatory and temporomandibular joint pain. This review also highlights the fact that BTX-A can effectively manage neuropathic pain and trigeminal neuralgia, which are difficult-to-treat chronic pain conditions. Herein, we present a comprehensive assessment of the central analgesic effects of BTX-A and a discussion of its various applications in clinical dental practice. CONCLUSION: BTX-A is an approved treatment option for various chronic pain conditions. Although there is evidence of axonal transport of BTX-A from peripheral to central endings in motor neurons, the precise mechanism underlying its pain-modulating effects remains unclear. This review discusses the evidence supporting the effectiveness of BTX-A in controlling chronic pain conditions in the orofacial region. BTX-A is a promising therapeutic agent for treating pain conditions that do not respond to conventional analgesics.

Development of a novel three-dimensional injection guide for trigeminal ganglia.

BACKGROUND: Trigeminal ganglion (TG) plays an important role in the process of orthodontic pain. It's necessary to design an accurate, precise and minimally invasive trigeminal ganglion injection guide plate to study TG. METHODS: Micro-CT was used to obtain the Dicom format data, and three-dimensional (3D) software (mimics and magics23.03) was used to reconstruct 3D head models. Design and modifications of the TG injection guide plate were performed in Magic 23.03 software, and the guide plate was produced by a 3D stereolithography printer. X-ray, micro-CT, Evans blue, and virus transduction were used to demonstrate the accuracy of the guide-assisted injection. Pain levels were evaluated after using the injection guide by a bite force test and Von Frey test. RESULTS: X-ray and micro-CT tests confirmed that the injection needle reached the bilateral trigeminal ganglia fossa. The Evans blue test and virus transduction proved that the injected drug could be accurately injected into the bilateral trigeminal ganglion and the lentivirus could be successfully transfected. The percentage of accurate injection was 10/10 (bilateral trigeminal ganglia). Orofacial pain induced by the trigeminal ganglion injection was mild and returned to baseline within seven days. CONCLUSION: The injection guide described in this study is viable and reliable for the delivery of drugs and virus transduction into the trigeminal ganglia.

Comparative effects of post isometric relaxation technique and Bowen's therapy on pain, range of motion and function in patients with temporomandibular joint disorder.

BACKGROUND: The most common cause of mouth and facial pain is a temporomandibular joint disorder, which affects the patient's quality of life and interferes with their ability to perform daily tasks. OBJECTIVE: The purpose was to compare the effects of the Post-Isometric Relaxation Technique and Bowen's Therapy on pain, range of motion and functional activity in patients with temporomandibular joint disorders. METHODS: This study was a randomized clinical trial. A total of 24 participants were randomly allocated into two groups using the lottery method. Baseline treatment was the same (ultrasound and tapping) in both groups. Group 1 (12 participants) was treated with a post-isometric relaxation technique, and Group 2 (12 participants) with Bowen's therapy for two sessions per week (total duration of 4 weeks). Outcome measures were the Numeric Pain Rating Scale, Maximal mouth opening inter-incisal rural and jaw functional limitation scale-20. SPSS version 25 was used for statistical analysis. RESULTS: A significant improvement in pain, range of motions and functional activities in the post-isometric group showed significant results (p < 0.05) as compared to Bowen's group (independent t-test). However, within-group comparison (paired t-test), both groups showed significant results (p < 0.05). CONCLUSION: This study concluded that post-isometric relaxation was more effective in terms of pain, range of motions for mouth opening, lateral deviations and functional activity of temporomandibular joint disorder patients. However, both groups showed clinical results according to minimal clinical difference values. TRIAL REGISTRY NUMBER: The trial is registered under ClinicalTrials.govt with reference no. ID: NCT05392049 registered on 26/05/2022.