Temporomandibular Joint Injection Research Articles

Update on Evidence and Directions in Temporomandibular Joint Injection Techniques: A Rapid Review of Primary Research

This rapid review summarizes the latest primary research in temporomandibular joint (TMJ) injection treatment. The final literature searches were conducted on 4 January 2024. Selection was performed systematically following predefined eligibility criteria. Randomized control trials concerning the treatment of TMJ disorders with intra-articular injections were included. Studies on more invasive interventions were excluded. Quality of life, joint pain and range of mandibular mobility were assessed. Ultimately, 12 studies covering a total of 603 patients qualified. They concerned: (1) arthrocentesis (AC) and the administration of, (2) injectable platelet-rich fibrin (I-PRF), (3) platelet-rich plasma (PRP), (4) hyaluronic acid (HA), (5) non-steroidal anti-inflammatory drugs (NSAIDs), and (6) hypertonic dextrose (HD) with a local anesthetic. The dominant approach was to perform arthrocentesis before administering the appropriate injection substance (I-PRF, PRP, HA, or NSAID). Two current studies on the intra-articular administration of NSAIDs, specifically tenoxicam and piroxicam, are noteworthy. A mixture of PRP and HA was injected in another two trials. These two innovative approaches may prove to be significant directions for further research on injection treatment of TMJs.

Update on Evidence and Directions in Temporomandibular Joint Injection Techniques: A Rapid Review of Primary Research

Update on Evidence and Directions in Temporomandibular Joint Injection Techniques: A Rapid Review of Primary Research

Temporomandibular Joint Injections and Lavage: An Overview of Reviews.

Objectives: This overview was conducted following the Preferred Reporting Items for Overviews of Reviews guidelines and aimed to collect and compare the results of systematic reviews on temporomandibular joint injection treatment. Methods: Systematic reviews of randomized clinical trials on temporomandibular disorders treated with lavage or intra-articular administrations were qualified for syntheses. The final searches were conducted on 27 February 2024, without time frame restrictions. Results: Of the 232 identified records, 42 systematic reviews were selected. The most evidence-based conclusions call into question the clinical differences between many therapeutic approaches, including the following: (1) injectable selection for the treatment of pain and hypomobility; (2) the method of performing arthrocentesis; (3) the use of imaging when rinsing the TMJ cavity; (4) the supplementation of the extracapsular administration of unprocessed blood with intracapsular deposition in the treatment of TMJ hypermobility. Conclusions: Systematic reviews based solely on randomized clinical trials proved the following differences: (1) in painful temporomandibular hypomobility, a better therapeutic effect is observed with arthrocentesis followed by I-PRF administration compared to lavage alone; (2) in painful temporomandibular hypomobility, inferior- or double-compartment injection leads to better results than superior-compartment injection; (3) in temporomandibular joint recurrent dislocation, hypertonic dextrose administration is superior to placebo, although (4) unprocessed blood has a better effect than hypertonic dextrose. PROSPERO registration number: CRD42024496142.

Temporomandibular joint injection therapy.

Temporomandibular joint injection therapy.

Ten years of injectable platelet-rich fibrin.

The use of platelet-rich fibrin (PRF) has seen widespread advantages over platelet-rich plasma (PRP) in many fields of medicine. However, until 2014, PRF remained clinically available only in its solid clotted form. Modifications to centrifugation protocols and tube technology have led to the development of a liquid injectable version of PRF (i-PRF). This narrative review takes a look back at the technological developments made throughout the past decade and further elaborates on their future clinical applications. Topics covered include improvements in isolation techniques and protocols, ways to further concentrate i-PRF, and the clinical impact and relevance of cooling i-PRF. Next, various uses of i-PRF are discussed, including its use in regenerative periodontology, implantology, endodontics, temporomandibular joint injections, and orthodontic tooth movement. Furthermore, various indications in medicine are also covered, including its use in sports injuries and osteoarthritis of various joints, treatment of diabetic ulcers/wound care, and facial esthetics and hair regrowth. Finally, future applications are discussed, mainly its use as a drug delivery vehicle for small biomolecules, such as growth factors, antibiotics, exosomes, and other medications that may benefit from the controlled and gradual release of biomolecules over time.

Efficacy of computer-guided versus conventional sodium hyaluronate injection in superior joint space in treatment of temporomandibular joint (TMJ) internal derangement: Comparative randomized controlled trial

Objectivesevaluate the feasibility and clinical outcomes of computer-guided sodium hyaluronate injection in superior joint space compared to conventional injection for the treatment of TMJ Internal Derangement (TMJ-ID). Patients and methodsRandomized controlled trial conducted on 40 patients diagnosed with bilateral TMJ-ID divided into two groups. Group A treated with four computer-guided sodium hyaluronate injections in superior TMJ space with one-week intervals. Group B received similar injections but with the conventional method. The intraoperative assessment included total procedural time and patient convenience during the injection. The postoperative evaluation included maximum unassisted mouth opening (MUMO), modified Helkimo's clinical dysfunction index, and pain intensity on a visual analog scale (VAS). ResultsGroup A showed better improvement in maximum mouth opening and pain intensity than group B after a week of the second, third and fourth injection. At the six months, group A continued to show better improvement regarding maximum mouth opening, while improvement in pain and TMJ dysfunction was similar in both groups. There were differences between both groups regarding procedural time and patient convenience across the study except the time of the first injection, which was similar in both groups ConclusionUsing the virtual planning and injection guide for intra-articular TMJ injection is considered promising to increase the accuracy and efficacy of injectable material securing faster results besides rendering the procedure easily reproducible and simpler to both clinicians and patients. However, the authors could not ensure the long-term superiority of the computer-guided injection technique over the conventional one in light of the results of this study.

A novel rat model of temporomandibular disorder with improved face and construct validities

AimsTemporomandibular disorders are a cluster of orofacial conditions that are characterized by pain in the temporomandibular joint (TMJ) and surrounding muscles/tissues. Animal models of painful temporomandibular dysfunction (TMD) are valuable tools to investigate the mechanisms responsible for symptomatic temporomandibular joint and associated structures disorders. We tested the hypothesis that a predisposing and a precipitating factor are required to produce painful TMD in rats, using the ratgnawmeter, a device that determines temporomandibular pain based on the time taken for the rat to chew through two obstacles. Materials and methodsIncreased time in the ratgnawmeter correlated with nociceptive behaviors produced by TMJ injection of formalin (2.5%), confirming chewing time as an index of painful TMD. Rats exposed only to predisposing factors, carrageenan-induced TMJ inflammation or sustained inhibition of the catechol-O-methyltransferase (COMT) enzyme by OR-486, showed no changes in chewing time. However, when combined with a precipitating event, i.e., exaggerated mouth opening produced by daily 1-h jaw extension for 7 consecutive days, robust function impairment was produced. Key findingsThese results validate the ratgnawmeter as an efficient method to evaluate functional TMD pain by evaluating chewing time, and this protocol as a model with face and construct validities to investigate symptomatic TMD mechanisms. SignificanceThis study suggests that a predisposition factor must be present in order for an insult to the temporomandibular system to produce painful dysfunction. The need for a combined contribution of these factors might explain why not all patients experiencing traumatic events, such as exaggerated mouth opening, develop TMDs.

Melatonin Abates TMJOA Chronic Pain by MT2R in Trigeminal Ganglion Neurons

Temporomandibular joint osteoarthritis (TMJOA) is one of the most common diseases causing chronic pain in the oral and maxillofacial region. So far, there are few ways to relieve the pain of TMJOA. Melatonin (MT) has a good analgesic effect in many diseases, including fibromyalgia, neuropathic pain, chronic headache, and burn pain, with very low acute toxicity and side effects. This study was to investigate the role and mechanism of MT in TMJOA chronic pain. In rats TMJOA chronic pain occurred at day 14 after an intra–temporomandibular joint injection of monosodium iodoacetate, which we previously reported. The enzyme-linked immunosorbent assay results showed that MT levels were higher in the synovial fluid from patients and rats with TMJOA as compared with those from control. Fluorescent retrograde tracing (Dil) identified that upregulation of MT type 2 receptor (MT2R) in trigeminal ganglion (TG) neurons innervating rat temporomandibular joints was accompanied by TMJOA chronic pain. Nociceptive behavior as assessed by von Frey and the Rat Grimace Scale demonstrated that exogenous administration of MT relieved chronic pain in TMJOA rats, whereas blocking MT2R with 4P-PDOT reversed the analgesic effect of MT. Immunofluorescence analysis also confirmed that MT inhibited CGRP and IB4 expression of TG neurons, and this inhibition was reversed by administering the MT2R antagonist in TMJOA rats. By using Fluo-3 AM-based calcium imaging in vitro, MT elicited calcium transients in Dil+ TG neurons, which were significantly abolished by 4P-PDOT. Collectively, this study suggested that MT relieves the TMJOA chronic pain of rats through downregulation of sensitized CGRP+ and IB4+ neurons in TG via MT2R. This will be helpful for health care professionals utilizing MT as an option against TMJOA chronic pain.

Collagen-Induced Temporomandibular Joint Arthritis Juvenile Rat Animal Model

Juvenile idiopathic arthritis can affect the temporomandibular joint (TMJ) that can cause growth disturbances of the lower jaw (mandible). The collagen-induced arthritis (CIA) juvenile rat model may be an appropriate model for studying how juvenile arthritis affects this joint during growth. However, studies using this animal model to investigate TMJ arthritis are limited. To validate an animal model for studying TMJ arthritis in growing rats, our study aimed to investigate the changes in mandibular growth and expression of proteins and cytokines in the mandibular condyle of CIA juvenile rat TMJs. A total of 27 male Wistar rats (3-weeks old) were scanned with micro-computed tomography (MicroCT) and divided into three groups (n=9). CIA was induced in each TMJ in the CIA group. The Saline group received saline injections (sham injections) into their TMJs, and the Healthy group remained untreated (no TMJ injections) as negative controls. After 4 weeks, our results show that mandibular growth was significantly reduced in the CIA group compared to the saline group (p < 0.01). There was no difference in mandibular growth between the two control groups (Saline and Healthy). Inflamed synovial tissue, cartilage invaginations, and lipid accumulation were observed in the CIA TMJs. Toluidine blue staining revealed decreased proteoglycan production in the CIA cartilage. As well, using immunohistochemistry, type II collagen expression decreased, interleukin-1β expression increased and matrix metalloproteinase-13 expression increased in the CIA TMJs in comparison with the two control groups (Saline and Healthy). Immunostaining of tumor necrosis factor-α (TNF-α) was quantifited and we showed that TNF-α expression was significantly greater in the CIA cartilage compared to both control groups (p < 0.05), and there was no difference in TNF-α expression between the Saline and Healthy groups. This CIA juvenile rat model of TMJ juvenile arthritis shows that CIA reduced mandibular growth and induced degenerative changes in TMJ condylar cartilage. This new information will help to understand the pathogenesis involved in CIA juvenile rat TMJs for this animal model to be used in research investigating new therapeutics to treat TMJ juvenile arthritis.

Temporomandibular joint injections in dogs with temporomandibular joint pain: 11 cases (2015-2019).

To describe and evaluate the clinical application of temporomandibular joint injections using betamethasone and ropivacaine in German Shepherd dogs suffering from non-odontogenic orofacial pain due to temporomandibular dysplasia and/or osteoarthritis. Outcomes in dogs presented with clinical signs of non-odontogenic orofacial pain associated to temporomandibular joint dysplasia and/or arthritis and treated with a temporomandibular joint injection were retrospectively-prospectively evaluated. The overall clinical signs free period ranged between 25 to 1579 days, with an average of 461 days. The clinical signs free period for temporomandibular joint osteoarthritis scores 1, 2 and 3 were on average 659 days (180-1579 days), 134 days (42-355 days) and 723 days (25-1377 days), respectively. Similarly the temporomandibular dysplasia scores 1, 2 and 3 were on average 306 days (26-1579 days), 1377 days and 669 days (25-1429 days) respectively. Those dogs in which only one side was injected the clinical signs free period average was 639 days (25-1578 days), compared with dogs in which both temporomandibular joints were injected showing a clinical signs free period average of 378 days (42-1377 days). The temporomandibular joint injection technique proved to be feasible with a decent outcome in dogs suffering from non-odontogenic orofacial pain associated with temporomandibular joint osteoarthritis and/or dysplasia. Further randomised studies are required to confirm the effectiveness of this intervention.

Immunoexpression of canonical Wnt and NF-κB signaling pathways in the temporomandibular joint of arthritic rats

To investigate the participation of canonical Wnt and NF-κB signaling pathways in an experimental model of chronic arthritis induced by methylated bovine serum albumin (mBSA) in rat temporomandibular joint (TMJ). Wistar rats were sensitized by mBSA+Complete Freund Adjuvant (CFA)/Incomplete Freund Adjuvant (IFA) on the first 14days (1×/week). Subsequently, they received 1, 2 or 3 mBSA or saline solution injections into the TMJ (1×/week). Hypernociceptive threshold was assessed during the whole experimental period. 24h after the mBSA injections, the TMJs were removed for histopathological and immunohistochemical analyses for TNF-α, IL-1β, NF-κB, RANKL, Wnt-10b, β-catenin and DKK1. The nociceptive threshold was significantly reduced after mBSA injections. An inflammatory infiltrate and thickening of the synovial membrane were observed only after mBSA booster injections. Immunolabeling of TNF-α, IL-1β and Wnt-10b was increased in the synovial membrane in arthritic groups. The immunoexpression of nuclear β-catenin was significantly higher only in the group that received 2 booster TMJ injections. However, NF-κB, RANKL and DKK1 immunoexpression were increased only in animals with 3 mBSA intra-articular injections. Our results suggest that canonical Wnt and NF-κB signaling pathways participate in the hypernociception and inflammatory response in TMJ synovial membrane during the development of rheumatoid arthritis in rats.

Ultrasound-guided versus blind temporomandibular joint injections: a pilot cadaveric evaluation

Temporomandibular disorders are painful conditions that require precise injection therapy in selected patients. This pilot cadaveric study was undertaken to compare the accuracy of temporomandibular joint (TMJ) injection between the anatomical landmark-based (blind) technique and an ultrasound-guided technique. TMJ injections using the blind technique or the ultrasound-guided technique were performed in 10 non-embalmed cadavers. After dissection, the accuracy of the TMJ injections was found to be significantly greater for the ultrasound-guided injections than for the blind technique (blind 55% vs. ultrasound 95%, P=0.008). For injections into the upper joint space of the TMJ, the success rate of the injection was comparable for the two techniques (blind 80% vs. ultrasound 100%, P=0.474). However, ultrasound-guided injections into the lower joint space had a much higher success rate than the blind technique (blind 30% vs. ultrasound 90%, P=0.020). The blind technique was associated with a considerable proportion of failed or inappropriate injections, especially for lower joint space injections. Ultrasound-guided TMJ injections were accomplished with a higher accuracy than the conventional blind technique, especially in the case of injections targeting the lower joint space of the TMJ.

Age, gender and parafunctional habits as prognostic factors for temporomandibular joint arthrocentesis

Objective: Arthrocentesis is an effective procedure for management of symptomatic patients with temporomandibular joint (TMJ) anterior disc displacement without reduction (ADDWOR), but its prognostic factors are still under investigation.Methods: Thirty-six patients with ADDWOR underwent arthrocentesis of the TMJ and hyaluronic acid injection. They were divided into groups based on three prognostic factors: Age, gender, and the presence of parafunctional habits. The procedure outcome (success or failure) was based on pre-set criteria for improvement in pain and maximum mouth opening (MMO) one month preoperatively.Results: Patients with parafunctional habits had a lower success rate than patients without these habits. Interesting trends were noted with age and gender as prognostic factors for arthrocentesis for patients with ADDWOR.Conclusion: Arthrocentesis is an effective management method for symptomatic patients with ADDWOR at one-month post treatment, especially in the absence of parafunctional habits.

Mechanisms involved in antinociception induced by a polysulfated fraction from seaweed Gracilaria cornea in the temporomandibular joint of rats

Temporomandibular disorder is a common clinical condition involving pain in the temporomandibular joint (TMJ) region. This study assessed the antinociceptive effects of a polysulfated fraction from the red seaweed Gracilaria cornea (Gc-FI) on the formalin-induced TMJ hypernociception in rats and investigated the involvement of different mechanisms. Male Wistar rats were pretreated with injection (sc) of saline or Gc-FI 1h before intra- TMJ injection of formalin to evaluate the nociception. The results showed that pretreatment with Gc-FI significantly reduced formalin-induced nociceptive behavior. Moreover, the antinociceptive effect of the Gc-FI was blocked by naloxone (a non-selective opioid antagonist), suggesting the involvement of opioids selective receptors. Thus, the pretreatment with selective opioids receptors antagonists, reversed the antinociceptive effect of the Gc-FI in the TMJ. The Gc-FI antinociceptive effect depends on the nitric oxide/cyclic GMP/protein kinase G/ATP-sensitive potassium channel (NO/cGMP/PKG/K+ATP) pathway because it was prevented by pretreatment with inhibitors of nitric oxide synthase, guanylate cyclase enzyme, PKG and a K+ATP blocker. In addition, after inhibition with a specific heme oxygenase-1 (HO-1) inhibitor, the antinociceptive effect of the Gc-FI was not observed. Collectively, these data suggest that the antinociceptive effect induced by Gc-FI is mediated by μ/δ/κ-opioid receptors and by activation NO/cGMP/PKG/K+ATP channel pathway, besides of HO-1.

Activational action of testosterone on androgen receptors protects males preventing temporomandibular joint pain

BackgroundTestosterone protects male rats from Temporomandibular Joint (TMJ) pain. This study investigated whether this protective effect is mediated by an organizational action of testosterone during nervous system development, by central estrogen and androgen receptors and by the 5α-reduced metabolite of testosterone, dihydrotestosterone. MethodsA pharmacological approach was used to assess the ability of the androgen receptor antagonist flutamide, the estrogen receptor antagonist ICI 182 780 and the 5-α reductase inhibitor dutasteride to block the protective effect of testosterone, evaluated through the behavioral response induced by a TMJ injection of 0.5% formalin. Flutamide and ICI 182 780 were injected into the medullary subarachnoid space, and dutasteride and testosterone were systemically administered. ResultsThe TMJ injection of 0.5% formalin induced a significant nociceptive behavioral response in gonadectomized male and naïve female, but not in sham gonadectomized male rats, confirming that endogenous testosterone prevents TMJ nociception in males. Testosterone administration prevented formalin-induced TMJ nociception in males gonadectomized either in the neonatal (at the day of birth) or adult period and in naïve female rats, suggesting that the protective effect of testosterone on TMJ nociception does not depend on its organizational actions during critical periods of development. The administration of flutamide and dutasteride but not of ICI 182 780 blocked the protective effect of testosterone. ConclusionsWe conclude that the protective effect of testosterone on TMJ nociception depends on activational actions of dihydrotestosterone on androgen receptors rather than on organizational androgenic actions during central nervous system development or estrogenic actions.

Coactivation of μ- and κ-Opioid Receptors May Mediate the Protective Effect of Testosterone on the Development of Temporomandibular Joint Nociception in Male Rats.

To investigate whether the protective effect of testosterone on the development of temporomandibular joint (TMJ) nociception in male rats is mediated by the activation of central opioid mechanisms. Experiments were performed on 156 male Wistar rats. A pharmacologic approach was used to assess the ability of opioid receptor antagonists infused into the dorsal portion of the brainstem and adjacent to the caudal component (subnucleus caudalis) of the spinal trigeminal nucleus to block the protective effect of testosterone in male rats. The TMJ injection of 0.5% formalin was used as a nociceptive stimulus. One-way or two-way ANOVA was used for data analyses. The injection of 0.5% formalin into the TMJ induced a significant nociceptive behavior in gonadectomized male rats (P < .05), but not in naïve, sham, and testosterone-replaced gonadectomized rats, confirming that testosterone prevents the development of TMJ nociception. The injection of either the nonselective opioid receptor antagonist naloxone (15 μg) or the simultaneous injection of the μ-opioid receptor antagonist Cys2, Tyr3, Orn5, Pen7amide (CTOP, 30 μg) and the κ-opioid receptor antagonist Nor-Binaltorphimine (Nor-BNI, 90 μg) significantly increased the 0.5% formalin-induced behavioral response in sham and testosterone-replaced gonadectomized rats (P < .05) but had no effect in gonadectomized rats. However, the injection of each selective opioid receptor antagonist alone or the simultaneous injection of μ- or κ- and δ-opioid receptor antagonists had no effect. These findings indicate that the protective effect of endogenous testosterone on the development of TMJ nociception in male rats is mediated by the activation of central opioid mechanisms. Furthermore, the coactivation of central μ- and κ-opioid receptors is necessary for testosterone to protect male rats from developing TMJ nociception.

Effects of experimental craniofacial pain on fine jaw motor control: a placebo-controlled double-blinded study.

The aim of the experiment was to test the hypothesis that experimental pain in the masseter muscle or temporomandibular joint (TMJ) would perturb the oral fine motor control, reflected in bigger variability of bite force values and jaw muscle activity, during repeated splitting of food morsels. Twenty healthy volunteers participated in four sessions. An intervention was made by injection of either 0.2 ml of monosodium glutamate/isotonic saline (MSG/IS) (randomized) in either the masseter or TMJ (randomized). The participants were asked to hold and split a flat-faced placebo tablet with their anterior teeth, thirty times each at baseline, during intervention and post-intervention. Pain was measured using a 0-10 visual analog scale. The force applied by the teeth to "hold" and "split" the tablet along with the corresponding electromyographic (EMG) activity of the jaw muscles and subject-based reports on perception of pain was recorded. The data analysis included a three-way analysis of variance model. The peak pain intensity was significantly higher during the painful MSG injections in the TMJ (6.1 ± 0.4) than the injections in masseter muscle (5.5 ± 0.5) (P = 0.037). Variability of hold force was significantly smaller during the MSG injection than IS injection in the masseter (P = 0.024). However, there was no significant effect of intervention on the variability of split force during the masseter injections (P = 0.769) and variability of hold and split force during the TMJ injections (P = 0.481, P = 0.545). The variability of the EMG activity of the jaw muscles did not show significant effects of intervention. Subject-based reports revealed that pain did not interfere in the ability to hold the tablet in 57.9 and 78.9 %, and the ability to split the tablet in 78.9 and 68.4 %, of the participants, respectively, during painful masseter and TMJ injections. Hence, experimental pain in the masseter muscle or TMJ did not have any robust effect in terms of bigger variability of bite force and jaw muscle activity, during repeated splitting of food morsels.

Infliximab partially alleviates the bite force reduction in a mouse model of temporomandibular joint pain.

Temporomandibular joint (TMJ) disorder is clinically important because of its prevalence, chronicity, and therapy-refractoriness of the pain. In this study, we investigated the effect of infliximab in a mouse model of TMJ pain using a specially-engineered transducer for evaluating the changes in bite force (BF). The mice were randomly divided into three groups (7 mice per group): the control group, the complete Freund's adjuvant (CFA) group, and the infliximab group. BF was measured at day 0 (baseline BF). After measuring the baseline BF, CFA or incomplete Freund's adjuvant was injected into both TMJs and then the changes in BF were measured at days 1, 3, 5, 7, 9, and 13 after the TMJ injection. For measuring the BF, we used a custom-built BF transducer. Control, CFA, and infliximab groups showed similar baseline BF at day 0. From day 1, a significant reduction in BF was observed in the CFA group, and this reduction in BF was statistically significant compared to that in the control group (P < 0.05). This reduction in BF was maintained until day 7, and BF started to recover gradually from day 9. In the infliximab group also, the reduction in BF was observed on day 1, and this reduction was maintained until day 7. However, the degree of reduction in BF was less remarkable compared to that in the CFA group. The reduction in BF caused by injection of CFA into the TMJ could be partially alleviated by the injection of anti-tumor necrosis factor alpha, infliximab.

Maresin 1 Inhibits TRPV1 in Temporomandibular Joint-Related Trigeminal Nociceptive Neurons and TMJ Inflammation-Induced Synaptic Plasticity in the Trigeminal Nucleus.

In the trigeminal system, disruption of acute resolution processing may lead to uncontrolled inflammation and chronic pain associated with the temporomandibular joint (TMJ). Currently, there are no effective treatments for TMJ pain. Recently, it has been recognized that maresin 1, a newly identified macrophage-derived mediator of inflammation resolution, is a potent analgesic for somatic inflammatory pain without noticeable side effects in mice and a potent endogenous inhibitor of transient receptor potential vanilloid 1 (TRPV1) in the somatic system. However, the molecular mechanisms underlying the analgesic actions of maresin 1 on TMJ pain are unclear in the trigeminal system. Here, by performing TMJ injection of a retrograde labeling tracer DiI (a fluorescent dye), I showed that maresin 1 potently inhibits capsaicin-induced TRPV1 currents and neuronal activity via Gαi-coupled G-protein coupled receptors in DiI-labeled trigeminal nociceptive neurons. Further, maresin 1 blocked TRPV1 agonist-evoked increases in spontaneous excitatory postsynaptic current frequency and abolished TMJ inflammation-induced synaptic plasticity in the trigeminal nucleus. These results demonstrate the potent actions of maresin 1 in regulating TRPV1 in the trigeminal system. Thus, maresin 1 may serve as a novel endogenous inhibitor for treating TMJ-inflammatory pain in the orofacial region.

Unlocking the jaw: advanced imaging of the temporomandibular joint.

Temporomandibular joint (TMJ) dysfunction is a common condition, affecting up to 28% of the population. The TMJ can be affected by abnormal dynamics of the disk-condyle complex, degenerative arthritis, inflammatory arthritis, and crystal arthropathy. Less commonly, neoplasms and abnormal morphologic features of the condyle are causes of TMJ symptoms. Cross-sectional imaging is frequently used for diagnosis. Knowledge of the normal imaging appearance of the TMJ, its appearance on radiological examination, and interventional techniques are useful for providing a meaningful radiologic contribution. This article will review normal TMJ anatomy; describe the normal ultrasound, CT, and MRI appearances of TMJ; provide imaging examples of abnormal TMJs; and illustrate imaging-guided therapeutic TMJ injection.