Bilateral TMJ Involvement in Rheumatoid Arthritis

The Role of Ultrasound in Temporomandibular Joint Disorders: An Update and Future Perspectives

Temporomandibular joint (TMJ) disorder is the second most common chronic pain condition affecting the general population after back pain. It encompasses a complex set of conditions, manifesting with jaw pain and limitation in mouth opening, influencing chewing, eating, speaking, and facial expression. TMJ dysfunction could be related to mechanical abnormalities or underlying inflammatory arthropathies, such as rheumatoid arthritis (RA) or juvenile idiopathic arthritis (JIA). TMJ exhibits a complex anatomy, and thus a thorough investigation is required to detect the TMJ abnormalities. Importantly, TMJ involvement can be completely asymptomatic during the early stages of the disease, showing no clinically detectable signs, exposing patients to delayed diagnosis, and progressive irreversible condylar damage. For the prevention of JIA complications, early diagnosis is therefore essential. Currently, magnetic resonance imaging (MRI) is described in the literature as the gold standard method to evaluate TMJ. However, it is a high-cost procedure, not available in all centers, and requires a long time for image acquisition, which could represent a problem notably in the pediatric population. It also suffers restricted usage in patients with claustrophobia. Ultrasonography (US) has emerged in recent years as an alternative diagnostic method, as it is less expensive, not invasive, and does not demand special facilities. In this narrative review, we will investigate the power of US in TMJ disorders based on the most relevant literature data, from an early screening of TMJ changes to differential diagnosis and monitoring. We then propose a potential algorithm to optimize the management of TMJ pathology, questioning what would be the role of ultrasonographic study.

Imaging of the Temporomandibular Joint

Temporomandibular disorder (TMD) is a common musculoskeletal condition that causes pain and disability for patients and imposes a high financial burden on the healthcare system. The most common cause of TMD is internal derangement, mainly secondary to articular disc displacement. Multiple other pathologies such as inflammatory arthritis, infection, and neoplasm can mimic internal derangement. MRI is the modality of choice for evaluation of the TMJ. Radiologists need to be familiar with the normal anatomy and function of the TMJ and MR imaging of the internal derangement and other less common pathologies of the TMJ.

Antinociceptive Actions of Botulinum Toxin A1 on Immunogenic Hypersensitivity in Temporomandibular Joint of Rats

Botulinum neurotoxin type A1 (BoNT-A) reduces the peripheral peptide and cytokine upregulation in rats with antigen-evoked persistent immunogenic hypersensitivity (PIH) of the temporomandibular joint (TMJ). Herein, we examined the effects of two preparations of BoNT-A, abobotulinumtoxinA (aboBoNT-A; Dysport) and onabotulinumtoxinA (onaBoNT-A; Botox), on spontaneous and evoked nociceptive behaviors, as well as on central neuronal and astroglial activation. The antigen-evoked PIH was induced in rats via repeated systemic and unilateral intra-articular (i.a.) injections of methylated bovine serum albumin (mBSA). Rats were subsequently injected with unilateral i.a. aboBoNT-A (14 U/kg), onaBoNT-A (7 U/kg), or the vehicle (saline). After i.a. treatments, spontaneous and mechanically evoked nocifensive behaviors were assessed before and after the low-dose i.a. formalin (0.5%) challenge. The central effects of BoNT-A were assessed by an immunohistochemical analysis of cleaved synaptosomal-associated protein 25 (cSNAP-25) presence, c-Fos, GFAP, and CGRP expression in the trigeminal nucleus caudalis (TNC). Both BoNT-A preparations similarly reduced the formalin-induced spontaneous pain-related behaviors and mechanical allodynia of the hypernociceptive rats. Likewise, their effects were associated with the central occurrence of cSNAP-25 and reduction of c-Fos and GFAP upregulation in the TNC. BoNT-A antinociceptive activity on the PIH is associated with the toxin axonal transport to trigeminal sensory areas and reduction of neuronal and glial activation in central nociceptive regions.

C-Reactive Protein Knockout Attenuates Temporomandibular Joint Inflammation in Rats

BACKGROUND

C-reactive protein (CRP), a biomarker of inflammation, is highly expressed in osteoarthritis- (OA-) related diseases, but its exact role remains unknown. In this study, we evaluated the biological effect of CRP on temporomandibular joint (TMJ) inflammation.

METHODS

Freund's complete adjuvant (CFA) was used to induce TMJ inflammation in CRP-knockout (CRP-/-) and control rats. Degenerative changes in the TMJ were compared to elucidate the role of CRP in TMJ inflammation. In addition, inflammatory cytokines, macrophage activation, and osteoclast differentiation were evaluated by real-time quantitative polymerase chain reaction, immunohistochemistry, and tartrate-resistant phosphatase staining to explore the potential regulatory mechanism.

RESULTS

Compared to the control, CFA induced TMJ inflammation, which increased systemic and local CRP expression. Furthermore, CRP-/- rats exhibited less severe inflammatory symptoms. The downregulation of proinflammatory cytokines (interleukin- (IL-) 1β and IL-6) and upregulation of the anti-inflammatory cytokine IL-10 were detected in CRP-/- rats, which also exhibited reduced macrophage activation and osteoclast differentiation.

CONCLUSION

These results indicated that controlling the highly elevated levels of CRP during inflammation could modify the cytokine profile, macrophage activation, and osteoclast differentiation, thus, providing beneficial effects for TMJ-OA prevention and treatment.

Nonsurgical management of temporomandibular joint autoimmune disorders

Introduction

Temporomandibular disorders (TMD) are observed in a number of autoimmune diseases but limited studies have assessed the effect of autoimmune diseases on TMD. Therefore, the present review article was conducted to determine the effect of autoimmune diseases on TMD.

Methods

International databases, including Web of Sciences, PubMed and Scopus, were searched in order to find related articles. The search key words were; temporomandibular joint (TMJ) autoimmune disorders, TMJ, TMD, medical therapy and non-invasive, local and systemic management. Published articles from June, 2010 to June, 2019 were included in the review.

Results

A total of 11 related articles including rheumatoid arthritis (RA), lupus erythematosus and systemic sclerosis were found. All articles noted that TMJ has unique features that distinguishes it from other human body joints. Cases of TMJ injury and TMD require specific treatments. Therefore, early diagnosis of TMD is essential. It was also mentioned in the articles that the collagen-induced arthritis (CIA) method is a suitable method for investigating TMD and its relationship with RA. Treatment methods included oral steroids, Disease-modifying antirheumatic drugs, nonsteroidal anti-inflammatory drugs, methotrexate 75 mg, and combination therapy with methotrexate.

Conclusion

Based on the results of this study, TMD exists in some autoimmune diseases, including RA, lupus erythematosus and systemic sclerosis. Therefore, there should be an interdisciplinary collaboration between physicians and dentists in order to choose the best conservative treatment and medication therapy for TMD to reduce the progression and pain associated with this type of disorder.

Crosstalk between Fas and S1P1 signaling via NF-kB in osteoclasts controls bone destruction in the TMJ due to rheumatoid arthritis

Rheumatoid arthritis (RA) mainly affects various joints of the body, including the temporomandibular joint (TMJ), and it involves an infiltration of autoantibodies and inflammatory leukocytes into articular tissues and the synovium. Initially, the synovial lining tissue becomes engaged with several kinds of infiltrating cells, including osteoclasts, macrophages, lymphocytes, and plasma cells. Eventually, bone degradation occurs. In order to elucidate the best therapy for RA, a comprehensive study of RA pathogenesis needs to be completed. In this article, we discuss a Fas-deficient condition which develops into RA, with an emphasis on the role of sphingosine 1-phosphate (S1P)/S1P receptor 1 signaling which induces the migration of osteoclast precursor cells. We describe that Fas/S1P1 signaling via NF-κB activation in osteoclasts is a key factor in TMJ-RA severity and we discuss a strategy for blocking nuclear translocation of the p50 NF-κB subunit as a potential therapy for attenuating osteoclastogenesis.

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

OBJECTIVE

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).

MATERIALS AND METHODS

Wistar rats were sensitized by mBSA+Complete Freund Adjuvant (CFA)/Incomplete Freund Adjuvant (IFA) on the first 14 days (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. 24 h 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.

RESULTS

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.

CONCLUSION

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.