Correlation of molecular biomarker concentrations between synovial fluid and saliva of the patients with temporomandibular disorders

Biomarkers in orofacial pain conditions: A narrative review

Orofacial pain conditions, including temporomandibular disorder, migraine, dental pain, and trigeminal neuralgia, are complex, multifactorial disorders with significant impacts on patients' quality of life. As understanding of the pathophysiology of these conditions has deepened, the role of molecular and genetic biomarkers in diagnosing, monitoring, and potentially treating orofacial pain has garnered increasing interest. This scoping review provides a comprehensive overview of the current state of research on biomarkers associated with orofacial pain conditions. By analyzing existing literature, we identify key biomarkers linked to inflammation, neural activity, and tissue degradation that are common across multiple conditions, as well as those specific to particular disorders. Our findings underscore the potential of these biomarkers to guide the development of personalized therapeutic strategies. However, the review also highlights the challenges faced by current biomarker research, including heterogeneity in study designs, small sample sizes, and a lack of longitudinal data. Addressing these challenges is critical for translating biomarker research into clinical practice and improving outcomes for patients with orofacial pain.

Stabilization Splint Therapy for Patients with Temporomandibular Disorders Improves Opening Movements and Jaw Limitation and Attenuates Pain by Influencing the Levels of IL-7, IL-8, and IL-13 in the Gingival Crevicular Fluid

Background and Objectives: In recent years, numerous studies have investigated and analyzed the levels of molecular biomarkers of temporomandibular disorders (TMD) from various tissue samples and body fluids. However, no study has investigated gingival crevicular fluid (GCF) in TMD patients. The purpose of this study was to determine the concentrations of pro-inflammatory cytokines in GCF before and after stabilization splint (SS) therapy in patients with painful TMD, to investigate whether SS administration causes changes in the concentrations of pro-inflammatory cytokines. An additional aim was to investigate the relationship of GCF cytokine levels with chronic pain intensity and clinical parameters. Materials and Methods: This prospective cohort study included 36 patients who were diagnosed with painful TMD using the Diagnostic Criteria for TMD (DC/TMD). GCF samples were collected at baseline before SS treatment (T0) and at one month (T1) and three months (T2) after the start of therapy. Customized ProcartaPlex Multiplex assays from eBioscience (Invitrogen™, Thermo Fisher Scientific, Viena, Austria) were used for the quantitative analysis of pro-inflammatory cytokines (IL-1β, IL-6, IL-7, IL-8, IL-13, and TNF-α). Patients filled out Croatian versions of questionnaires for self-assessment from Axis II DK/TMP: Graded Chronic Pain Scale (v2) (GCPSv2) and Jaw Function Limitation Scale-20 (JFLS-20). Results: The results showed that the GCF levels of IL-7 (Friedman's test, p = 0.008) and IL-13 (Friedman's test, p = 0.003) were significantly decreased at T2. The GCF level of IL-13 was in negative correlation with chronic pain grade score at T2 (Rho = -0.333), while the GCF level of IL-8 was in positive correlation with mobility limitation (Rho = 0.382) at T1. Conclusions: The results indicate that SS therapy might have a role in reducing inflammation and that the GCF could be a valuable medium for assessing molecular biomarkers.

Assessment of self-rated pain perception and whole salivary cortisol levels among adolescents with and without temporomandibular disorders

OBJECTIVE

To assess the self-perceived pain perception (PP) and whole salivary cortisol levels (CL) among adolescents with and without temporomandibular disorders (TMD).

METHODS

Adolescents between 15 and 17 years were included. Participants were categorized into three groups: Group 1: patients with TMD; Group 2: nocturnalbruxers without TMD; and Group 3: controls. Demographic data CL and self-rated PP were assessed. A p-value < 0.05 was proposed as statistically significant.

RESULTS

Fifty-four patients (18 per group) were included. Scores of self-rated PP in the affected TMJ were higher in Group 1 than Group 2 (p < 0.001). Whole salivary CL were higher in groups 1 and 2 (p < 0.01) than in Group 3. Whole salivary CL were higher in Group 2 than Group 3 (p < 0.05).

CONCLUSION

Whole salivary CL are higher in adolescents with TMD, and there is a direct relationship between self-rated PP in the TMJ area and salivary CL.

Comparative evaluation of the trabecular structure of the mandibular condyle, the levels of salivary cortisol, MMP-3, TNF-α, IL-1β in individuals with and without temporomandibular joint disorder

OBJECTIVE

Temporomandibular disorder (TMD) is still a challenge in terms of diagnosis and management. The aim of this study is to explore if the evaluation of salivary biomarkers and fractal dimension (FD) of mandibular condyle could be useful for interpreting early degenerative changes and the effectiveness of salivary cortisol in determining the stress levels of TMD patients.

MATERIALS AND METHODS

34 patients with TMD, and 34 healthy controls were included in this study. Saliva samples were obtained from all participants between 09:00-12:00 am. Salivary cortisol, IL-1β, TNF-α, and MMP-3 levels were evaluated with ELISA method. FD of the mandibular condyle was determined by means of box-counting method. Depression and anxiety were determined with PHQ-9 and GAD-7 questionnaires.

RESULTS

The salivary cortisol and depression/anxiety were higher in study group; however, not significant (p>0.05). FD of the study group was found significantly lower than the control group (p<0.01). Salivary TNF-α, IL-1β and MMP-3 levels were showed no significant difference between the two groups (p>0.05). There were no significant correlations between the evaluated parameters.

CONCLUSION

Salivary cortisol seems to be a non-invasive way of measuring physiological stress of TMD patients. Fractal analysis may be a useful tool in detecting early structural changes in mandibular condyle. Salivary TNF-α. IL-1β and MMP-3 have not a diagnostic value in terms of interpreting early degenerative changes.

Efficacy of laser therapy for temporomandibular disorders: A systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review was to evaluate the efficacy of laser therapy in temporomandibular disorders (TMD).

METHODS

Randomized controlled trials (RCTs) in regard to this issue were searched in electronic databases. Three investigators independently screened the eligible studies, and the quality of the included studies was assessed according to the risk of bias tool recommended by the Cochrane handbook. The primary outcome measure was the degree of pain, reported on a visual analog scale (VAS), and the secondary outcome measures were TMJ function, including maximum active vertical opening (MAVO), maximum passive vertical opening (MPVO), left and right lateral movement (LLE, RLE). Pooled effect sizes were calculated using random effects models and 95% confidence interval (95% CI).

RESULTS

A total of 28 randomized controlled trials were included. Laser therapy had a more significant effect in terms of VAS (SMD=﹣1.88; 95% CI=﹣2.46 to﹣1.30; P<0.00001; I² =93%), MAVO (MD = 4.90; 95% CI= 3.29 to 6.50; P < 0.00001; I² =72%), MPVO (MD=5.8²; 95% CI= 4.62 to 7.01; P<0.00001; I² =40%) and RLE (MD = 0.73; 95% CI= 0.23 to 1.22; P = 0.004; I² = 0%) as compared to placebo group. However, there was no significant difference in LLE between two groups (MD= 0.35; 95% CI=﹣0.31 to 1.01; P=0.30; I² =0%).

CONCLUSIONS

Laser therapy can effectively reduce pain but have small effect on improving mandibular movement of TMD patients. More well-designed RCTs with large sample sizes are needed for further validation. And these studies should report detailed laser parameters and provide complete outcome measure data.

PROSPERO

CRD42022349719.

Identification of crucial salivary proteins/genes and pathways involved in pathogenesis of temporomandibular disorders

Temporomandibular disorder (TMD) is a collective term for a group of conditions that lead to impairment of the function of the temporomandibular joint. The proteins/genes and signaling pathways associated with TMD are still poorly understood. The aim of this study was to identify key differentially expressed salivary proteins/genes (DEGs) associated with TMD progression using LC-MS/MS coupled with a bioinformatics approach. The protein–protein interaction network was obtained from the STRING database and the hub genes were identified using Cytoscape including cytoHubba and MCODE plug-ins. In addition, enrichment of gene ontology functions and the Reactome signaling pathway was performed. A total of 140 proteins/genes were differentially expressed. From cluster analysis, a set of 20 hub genes were significantly modulated: ALB, APOA1, B2M, C3, CAT, CLU, CTSD, ENO1, GSN, HBB, HP, HSPA8, LTF, LYZ, MMP9, S100A9, SERPINA1, TF, TPI1, and TXN. Two enriched signaling pathways, glycolysis and gluconeogenesis, and tryptophan signaling pathway involving the hub genes CAT, ENO1, and TPI1 have been identified. The rest of the hub genes were mainly enriched in the innate immune system and antimicrobial peptides signaling pathways. In summary, hub DEGs and the signaling pathways identified here have elucidated the molecular mechanisms of TMD pathogenesis.

Influence of different sample preparation strategies on hypothesis-driven shotgun proteomic analysis of human saliva

This research aimed to find an efficient and repeatable bottom-up proteolytic strategy to process the unstimulated human saliva. The focus is on monitoring immune system activation via the cytokine and interleukin signaling pathways. Carbohydrate metabolism is also being studied as a possible trigger of inflammation and joint damage in the context of the diagnostic procedure of temporomandibular joint disorder. The preparation of clean peptide mixtures for liquid chromatography–mass spectrometry analysis was performed considering different aspects of sample preparation: the filter-aided sample preparation (FASP) with different loadings of salivary proteins, the unfractionated saliva, amylase-depleted, and amylase-enriched salivary fractions. To optimize the efficiency of the FASP method, the protocols with the digestion in the presence of 80% acetonitrile and one-step digestion in the presence of 80% acetonitrile were used, omitting protein reduction and alkylation. The digestion procedures were repeated in the standard in-solution mode. Alternatively, the temperature of 24 and 37°C was examined during the trypsin digestion. DyNet analysis of the hierarchical networks of Gene Ontology terms corresponding to each sample preparation method for the bottom-up assay revealed the wide variability in protein properties. The method can easily be tailored to the specific samples and groups of proteins to be examined.

Adipokines in dental pulp: physiological, pathological, and potential therapeutic roles

BACKGROUND

Hundreds of adipokines have been identified, and their extensive range of endocrine functions-regulating distant organs such as oral tissues-and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications.

HIGHLIGHTS

The most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation.

CONCLUSION

Adipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.

A comprehensive review on biomarkers associated with painful temporomandibular disorders

Pain of the orofacial region is the primary complaint for which patients seek treatment. Of all the orofacial pain conditions, one condition that possess a significant global health problem is temporomandibular disorder (TMD). Patients with TMD typically frequently complaints of pain as a symptom. TMD can occur due to complex interplay between peripheral and central sensitization, endogenous modulatory pathways, and cortical processing. For diagnosis of TMD pain a descriptive history, clinical assessment, and imaging is needed. However, due to the complex nature of pain an additional step is needed to render a definitive TMD diagnosis. In this review we explicate the role of different biomarkers involved in painful TMD. In painful TMD conditions, the role of biomarkers is still elusive. We believe that the identification of biomarkers associated with painful TMD may stimulate researchers and clinician to understand the mechanism underlying the pathogenesis of TMD and help them in developing newer methods for the diagnosis and management of TMD. Therefore, to understand the potential relationship of biomarkers, and painful TMD we categorize the biomarkers as molecular biomarkers, neuroimaging biomarkers and sensory biomarkers. In addition, we will briefly discuss pain genetics and the role of potential microRNA (miRNA) involved in TMD pain.