Temporomandibular joint function, periodontal health, and oral microbiome in early rheumatoid arthritis and at-risk individuals: a prospective cohort study protocol

Causal Relationship Between Autoimmune Arthritis and Temporomandibular Disorders

OBJECTIVE

Accumulating evidence has indicated a close interrelation between autoimmune arthritis (AA) and temporomandibular disorders (TMD), but the causality is still unclear. The study aimed to explore the causal inference between AA and TMD using a bidirectional Mendelian randomization analysis.

METHODS

Online genome-wide association study data on rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis, and TMD were obtained from the FinnGen and IEU databases. Causality was using the inverse variance-weighted method as the primary analysis and supplemented by other methods. Sensitivity analyses, including heterogeneity tests, horizontal pleiotropy tests, and leave-one-out methods, were conducted to investigate the stability and reliability of the results.

RESULTS

The inverse variance-weighted test indicated that several AA types could causally increase the TMD risk, including overall RA (odds ratio [OR] = 1.348, 95% confidence interval [CI] = 1.1232-1.618, P = .001), subtype nRA (OR = 1.118, 95% CI = 1.044-1.197, P = .001), and AS (OR = 1.060, 95% CI = 1.024-1.097, P = .001). Moreover, the causal association of the above combinations has been proven to be stable and reliable using sensitivity and other tests.

CONCLUSION

These findings suggest that RA and AS might be causally associated with an increased risk of TMD. However, more studies are needed to check the causal effects of AA on TMD and analyse the potential mechanisms further.

Association between periodontitis and temporomandibular joint disorders

BACKGROUND

Periodontitis (PD) may affect temporomandibular joint disorders (TMD) and TMD may influence PD in previous observational studies. Nevertheless, these studies were prone to confounders and reverse causation, leading to incorrect conclusions about causality and direction of association. This research investigates the associations between PD and TMD employing bidirectional two-sample Mendelian randomization (MR) analysis.

METHODS

Single-nucleotide polymorphisms (SNPs) related to PD (p < 5 × 10-6) were selected from a genome-wide association study (GWAS) from the Gene-Lifestyle Interaction in the Dental Endpoints (GLIDE) consortium, and related these to SNPs from FinnGen and UK Biobank (UKB) consortia, and vice versa. We implemented the standard inverse variance weighted (IVW), weighted median (WM), MR-Egger regression, and MR-PRESSO methods to estimate the potential causality between PD and TMD. Sensitive tests were conducted using robust MR methods. Results from FinnGen and UKB were combined using the fixed model.

RESULTS

PD did not appear to causally affect TMD. Additionally, the reverse MR analysis did not reveal a significant causal effect of TMD on PD. The results of other MR methods were similar to those of the IVW method. Sensitivity analyses addressed no potential pleiotropy in MR estimations. Results from the meta-analysis were consistent with the above-mentioned consequences.

CONCLUSION

This research does not support a causal relationship between PD and TMD. PD does not appear to worsen TMD directly, and vice versa.

Cranial structure and condylar asymmetry of adult patients with rheumatoid arthritis

OBJECTIVE

The aim of this prospective cross sectional study was to evaluate the cranial structure and condylar asymmetry of adult patients with rheumatoid arthritis (RA) diagnosed after 25 years of age compared to a healthy adult control group.

METHODS

Eighteen adult patients (57.4 ± 11.4 years) with RA were compared with a control group. Cephalometric analysis and the Habets method for the calculation of the condylar asymmetry were used. The main cephalometric data investigated were focused on the diagnosis of hyperdivergent cranial structure (NSL/ML, NL/ML), backwards rotation of the mandible (Fh/ML), short vertical ramus (Ar:Go), steep mandibular plane (ML/Oc).

RESULTS

The cephalometric data considered were not significantly different in the RA vs controls except for the steepness of the occlusal plane (NL/Oc), which was steeper in the patients group (P < 0.02) and the ramus of the mandible which was greater in patients. The asymmetry of the condyles was significant (P < 0.003) and different from the control group, but that of the ramus was not.

CONCLUSIONS

In this study, RA patients diagnosed after 25 years of age did not show a different pattern of growth with respect to the control group. As expected, the condyles showed a difference being asymmetrical in RA patients due to the high turnover of this joint reacting to severe systemic inflammation in conditions of continuous functional work, load and forces. This study follows a previous study with the same research plan conducted on young JIA patients who showed a different pattern of growth of the skull leading to a severe hyperdivergent cranial structure with backward rotation of the mandible; this is mainly due to the insufficient growth of the condylar site exposed to the inflammatory process during development. Unlike JIA patients, this study showed that RA patients follow an individual growth pattern not affected by inflammation, even if they show joint asymmetry.

Temporomandibular joint arthritis increases canonical Wnt pathway expression in the articular cartilage and trigeminal ganglion in rats

The canonical Wnt pathway participates in inflammatory diseases and it is involved in neuropathic pain. This study evaluated the immunoexpression of the canonical Wnt signaling pathway in the articular cartilage of the temporomandibular joint (TMJ) and along the nociceptive trigeminal pathway in arthritic rats. For this, male Wistar rats were divided into Control (C) and Arthritic (RA) groups. Arthritis induction was performed through subcutaneous injection of methylated bovine serum albumin (mBSA) and complete Freund Adjuvant (CFA)/ Incomplete Freund Adjuvant (IFA) on the first 14 days (once a week), followed by 3 weekly intra-articular injections of mBSA (10 μl/joint; left TMJ). The following parameters were evaluated: nociceptive threshold, inflammatory infiltrate, type I and III collagen birefringence, immunohistochemistry for IL-1β, TNF-α, IL-6, Wnt10b, β-catenin, cyclin-D1 in articular cartilage, c-Myc in synovial membrane, and immunofluorescence analysis for c-Fos, Wnt-10b and β-catenin in the trigeminal ganglion and the trigeminal subnucleus caudalis. The RA group showed intense articular cartilage damage with proliferation of type III collagen, increased immunoexpression of proinflammatory cytokines and Wnt-10b, β-catenin and cyclin-D1 in the articular cartilage and c-Myc in the synovial membrane. In the RA group, a reduction in the nociceptive threshold was observed, followed by a significant increase in the expression of Wnt-10b in neurons and β-catenin in satellite cells of the trigeminal ganglion. c-Fos immunoexpression was observed in neurons, peripherally and centrally, in arthritic rats. Our data demonstrated that TMJ arthritis in rats causes articular cartilage damage and nociceptive behavior, with increased immunoexpression of canonical Wnt pathway in the articular cartilage and trigeminal ganglion.

Oral health-related quality of life in patients with early rheumatoid arthritis is associated with periodontal inflammation and painful temporomandibular disorders: a cross-sectional study

OBJECTIVES

To evaluate oral health-related quality of life (OHRQoL) in early rheumatoid arthritis (ERA) patients and individuals at risk of rheumatoid arthritis (RA) compared to healthy controls, and to explore possible associated factors.

MATERIALS AND METHODS

Fifty ERA patients, 50 at-risk individuals, and 50 age and gender matched healthy controls were recruited. OHRQoL (Oral Health Impact Profile-14 (OHIP-14)); number of decayed, missing, and filled teeth (DMFT); denture use; periodontal inflamed surface area (PISA); xerostomia (xerostomia inventory (XI)); and possible TMD (-pain) diagnoses were recorded. The groups were compared on these variables. Subsequently, backward multiple regression analyses were performed for the ERA and at-risk groups, with OHRQoL as the dependent variable and gender, age, DMFT, denture use, PISA, XI, non-painful TMD, and TMD pain as independent variables.

RESULTS

At-risk individuals had higher XI scores (U = 789.5, z = -3.181, p = 0.001, r = -0.32) and higher prevalence of TMD pain (p = 0.046, OR = 4.57; 95% CI 0.92-22.73) than healthy controls and higher OHIP-14 scores than the ERA group (U = 894.5, z = -2.418, p = 0.016, r = -0.24), while no difference in OHIP-14 was found between the control group and both other groups. For ERA patients, OHRQoL was associated with PISA and TMD pain (R2 = 0.498, p < 0.001). For at-risk individuals, OHRQoL was associated with XI score (R2 = 0.410, p < 0.001).

CONCLUSIONS

Alertness of health professionals to TMD pain and periodontal inflammation in ERA patients and to xerostomia and TMD pain in at-risk individuals is recommended.

CLINICAL RELEVANCE

The results of this study address orofacial aspects that require attention of health professionals in the timeframe around RA onset.

TRIAL REGISTRATION

Dutch National Trial Register (NTR, NTR6362).

BDJ Open (2019-2020) and the advantages of open access publishing

BDJ Open is the open access sister journal to the British Dental Journal, and this paper aims to explore the various different articles that BDJ Open has published between 2019 and 2020, in order to highlight which areas authors felt were important to publish open access. Furthermore, this article will investigate the advantages of open access publishing to both authors and readers, as well as the scientific community in general, and will examine how open access publishing has allowed the BDJ Portfolio to publish a wide range of research, both in terms of topic and geography.

Examines papers published in BDJ Open between 2019 and 2020 to highlight which areas researchers felt were important to publish open access.

Discusses the advantages of open access publishing to authors, readers and the scientific community.

Explores how open access publishing has allowed the BDJ Portfolio to publish a far wider range of research both geographically and subject-wise.

The oral microbiome in early rheumatoid arthritis patients and individuals at risk differs from healthy controls

OBJECTIVE

It has been suggested that rheumatoid arthritis (RA) may originate at the oral mucosa. Our aim was to assess the oral microbiome and the periodontal condition in patients with early rheumatoid arthritis (ERA) and individuals at risk of RA.

METHODS

Three groups were recruited (50 participants each): (1) ERA patients (2010 ACR/EULAR criteria), (2) at-risk individuals (arthralgia and autoantibodies), and (3) healthy controls. A periodontal examination resulted in scores for bleeding on probing (BOP), pocket probing depth (PPD), and periodontal inflamed surface area (PISA). The microbial composition of subgingival dental plaque, saliva, and tongue coating was assessed using 16S rDNA amplicon sequencing, and compared between groups with permutational multivariate analyses of variance (PERMANOVA).

RESULTS

There was no difference between the groups on the periodontal variables (BOP p=0.70; PPD p=0.30; PISA p=0.56). PERMANOVA showed a difference between the groups in the microbial composition of saliva (F=2.08, p<0.001) and tongue coating (F=2.04, p=0.008), but not plaque (p=0.51). Post-hoc tests showed no difference between the ERA group and at-risk group (saliva F=1.12, p=0.28; tongue coating F=0.834, p=0.59). Discriminative zero-radius operational taxonomic units (zOTUs) were identified: in ERA patients and at-risk individuals, Prevotella in saliva and Veillonella in saliva and tongue coating were at higher relative abundance compared to healthy controls.

CONCLUSION

The results show similarities in the oral microbiome between ERA patients and at-risk individuals, both presenting with increased relative abundance of potentially pro-inflammatory species compared to healthy controls, suggesting a possible association between the oral microbiome and RA onset.

Comparative Analysis of the Temporomandibular Joints in Patients with Chronic Periodontitis Using Cone-Beam Computed Tomography (CBCT)

INTRODUCTION

Chronic periodontitis is a common disorder in adults causing periodontal destruction and loss of teeth. These clinical presentations may lead to temporomandibular joint disorders (TMDs). This study aimed to examine the anatomic structures of the temporomandibular joints (TMJs) using cone-beam computed tomography (CBCT) in patients with chronic periodontitis.

METHODS

Fifty patients with chronic periodontitis were enrolled in the study. Based on the severity of chronic periodontitis, these patients were divided into the mild, moderate, and severe groups. CBCT images of TMJs were acquired and reconstructed. Several indices on the reconstructed CBCT images were collected and analyzed, such as the oblique joint space parallel to the long axis of the condyle, the long axis diameter of the condyle, the vertical angle of the condyle, the inclination of the articular eminence vertical to the long axis of condyle at the oblique and sagittal positions, the depth of the fossa, and the horizontal angle of the cross-sections. The measurements between right and left sides of each patient were compared. Statistical analysis (paired samples t test) was performed.

RESULTS

The differences of the joint space vertical to the bilateral condyles were statistically significant (P < 0.05). Additionally, in the severe periodontitis group, the distances between the inner and outer poles of the condyles were statistically different (P < 0.05).

CONCLUSION

In patients with chronic periodontitis, TMJ space vertical to the condyles and the distances between the outer and inner poles of the condyle may change over time. These two indices can potentially be used as indicators for diagnosis and further comparative analyses.

Temporomandibular disorders in patients with early rheumatoid arthritis and at-risk individuals in the Dutch population: a cross-sectional study

OBJECTIVE

To evaluate the prevalence of temporomandibular disorders (TMD) in patients with early rheumatoid arthritis (ERA) and individuals at-risk of RA.

METHODS

150 participants were recruited in three groups (50 per group): (1) patients with ERA (2010 EULAR criteria) (2) at-risk individuals and (3) healthy controls. All participants were tested for seropositivity of rheumatoid factor and anticitrullinated protein antibodies. A possible TMD diagnosis was determined according to the standardised and validated diagnostic criteria for TMD (DC/TMD) in five categories: myalgia, arthralgia, articular disc displacement, degenerative joint disease and headache attributed to TMD. Results were tested for the prevalence of TMD (all categories combined) and TMD pain (myalgia and/or arthralgia). To investigate a possible role for bruxism, a probable sleep and/or awake bruxism diagnosis was determined based on self-report and several clinical features.

RESULTS

The prevalence of any TMD diagnosis did not differ between the three groups. However, at-risk individuals more often had a TMD-pain diagnosis than healthy controls (p=0.046). No such difference was found between the ERA group and the control group. However, within the ERA group, seronegative patients had a TMD-pain diagnosis more often than seropositive patients (4/12 (33%) vs 3/38 (8%), p=0.048). Participants with a TMD-pain diagnosis were more often diagnosed with probable sleep bruxism than those without a TMD-pain diagnosis.

CONCLUSION

The prevalence of TMD pain is increased in individuals at-risk of RA and seronegative ERA patients, and is associated with bruxism signs and symptoms. These results suggest that health professionals should be alert to TMD pain in these groups.

1H-NMR-Based salivary metabolomics from females with temporomandibular disorders - A pilot study

Although temporomandibular disorder (TMD) is the second most common musculoskeletal disorder in the general population, the disease is multifactorial and presents symptoms common to other conditions which misdiagnosis can lead to treatment failure. In this case-control study, we performed, for the first time, a high-resolution ¹H-nuclear magnetic resonance spectroscopy metabolomic analysis of the saliva of 26 women with TMD of muscular origin (experimental group [EG]) at the beginning (EG-pre) and at the end (EG-post) of a conservative treatment, and of 27 normal women (control group [CG]) to identify a metabolic signature for TMD. One-way analysis of variance showed changes in the concentration of phenylacetate, dimethylamine, maltose, acetoin, and isovalerate. Partial least-square discriminant analysis showed that metabolite signals did not overlap in CG X EG-pre and EG-pre X EG-post, but overlapped in CG X EG-post. The area under the receiver operating characteristic curve was 1 in CG X EG-pre (95% CI, 1.000-1.000; p < 0.002), 0.993 in EG-pre X EG-post (95% CI, 0.963-1.000), and 0.832 in CG X EG-post (95% CI, 0.699-0.961). These results suggest that the metabolomic profiles of women with and without TMD differ, while after treatment there is a lower distinction and slight tendency towards overlapping between CG and EG-post compared to pre treatment. We also found that phenylacetate, dimethylamine, maltose, acetoin, and isovalerate are potential biomarkers for TMD of muscular origin.