The association of genetic polymorphisms in serotonin transporter and catechol‐O‐methyltransferase on temporomandibular disorders and anxiety in adolescents

Genome-Wide Association Study of Temporomandibular Disorder-Related Pain in Finnish Populations

BACKGROUND

Temporomandibular disorders (TMD) are multifactorial musculoskeletal pain and dysfunctions in temporomandibular joints (TMJs) and masticatory muscles. Genetic factors play a role in TMD-related pain, but only a few genome-wide association studies (GWAS) have been conducted.

OBJECTIVE

The aim of this GWAS was to explore genetic factors associated with painful TMD in Finnish populations.

METHODS

Data from two epidemiological surveys, the Northern Finland Birth Cohort 1966 (NFBC1966) and the Health 2000 Survey in Finland, including altogether 468 cases and 6833 controls, were used. Case definition was based on pain on palpation of masticatory muscles and/or TMJs. GWASs of the whole data and stratified by sex were conducted from both cohorts using additive models, followed by meta-analysis of the two cohorts. Replications of the previously reported TMD risk loci (rs73460075, DMD; rs4794106, SGCA; rs73271865, SP4; rs60249166, RXP2; rs1531554, BAHCCI; rs5862730, OTUD4/SMAD1; rs10092633, SFRP1; rs34612513, SOX14/CLDN18; rs878962, TSPAN9) were also investigated.

RESULTS

Four genome-wide significant loci were found in sex-stratified analysis of NFBC1966, including associations at three loci in males (rs1023114, PRIM2, p = 5 × 10-9; rs4244867, ALG10, p = 3 × 10-8; rs79841648, ADCYAP1, p = 4 × 10-9) and one locus in females (rs148476652, DNER, p = 4 × 10-9). However, the results could not be replicated in the Health 2000 Survey or in the meta-analysis of these two cohorts. The previous TMD GWAS associations did not replicate in our data either.

CONCLUSION

Several TMD pain-associated variants were found in sex-stratified analysis of NFBC1966, suggesting the role of neuroendocrine stress responses and central nervous system. These findings need to be confirmed in future studies.

The association between genetic factors and temporomandibular disorders: A systematic literature review

OBJECTIVE

This study aimed to investigate the correlation between genetic factors and the occurrence and progression of temporomandibular disorders (TMDs) using a comprehensive review and meta-analysis.

DESIGN

A comprehensive search was conducted using the ScienceDirect, PubMed, Cochrane Library, Dimensions, and Emerald databases. A reviewer selected the study using modified PICO criteria, considering human subjects with TMDs, comparing different genetic factors among TMD and non-TMD patients, and reporting TMD signs and symptoms as outcomes. The methodological standards of the eligible papers were assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Non-randomized Experimental Investigations. Information was collected methodically and examined.

RESULTS

The electronic database search yielded 851 articles, 19 of which were included in this study. The data analysis showed a significant influence of genetic factors, such as polymorphisms and gene differences, on the development of TMD signs and symptoms, such as myofascial pain, chronic pain, and disc displacement. In addition, gene polymorphism significantly influenced TMD development, with an odds ratio of 2.46 (1.93-3.14) and p of 0.00001.

CONCLUSIONS

Genetic factors significantly influenced TMD signs and symptoms, and genetic polymorphisms significantly influenced TMD onset and progression. Further research should be conducted in diverse settings with larger sample sizes to verify and validate these findings.

Multivariate analysis of oral mucosal ulcers during orthodontic treatment

BACKGROUND

Orthodontic treatment can easily cause local soft tissue reactions in the oral cavity of patients under mechanical stress, leading to oral mucosal ulcers and affecting their quality of life. At present, only limited literature has explored the factors leading to oral ulcers in orthodontic treatment, and these research results are still controversial.

AIM

To investigate the current status and related factors of oral mucosal ulcers during orthodontic treatment, aiming to provide a valuable reference for preventing this disease in clinical practice.

METHODS

A total of 587 patients who underwent orthodontic treatment at the Peking University School of Stomatology and Hospital of Stomatology between 2020 and 2022 were selected and allocated to an observation or control group according to the incidence of oral mucosal ulcers during orthodontic therapy. A questionnaire survey was constructed to collect patient data, including basic information, lifestyle and eating habits, treatment details, mental factors, and trace element levels, and a comparative analysis of this data was performed between the two groups.

RESULTS

A logistic regression model with oral ulcers as the dependent variable was established. The regression results showed that age (≥ 60 years: odds ratio [OR]: 6.820; 95% confidence interval [CI]: 2.226-20.893), smoking history (smoking: OR: 4.434; 95%CI: 2.527-7.782), toothbrush hardness (hard: OR: 2.804; 95%CI: 1.746-4.505), dietary temperature (hot diet: OR: 1.399; 95%CI: 1.220-1.722), treatment course (> 1 year: OR: 3.830; 95%CI: 2.203-6.659), and tooth brushing frequency (> 1 time per day: OR: 0.228; 95%CI: 0.138-0.377) were independent factors for oral mucosal ulcers (P < 0.05). Furthermore, Zn level (OR: 0.945; 95%CI: 0.927-0.964) was a protective factor against oral ulcers, while the SAS (OR: 1.284; 95%CI: 1.197-1.378) and SDS (OR: 1.322; 95%CI: 1.231-1.419) scores were risk factors.

CONCLUSION

Age ≥ 60 years, smoking history, hard toothbrush, hot diet, treatment course for > 1 year, tooth brushing frequency of ≤ 1 time per day, and mental anxiety are independent risk factors for oral mucosal ulcers. Therefore, these factors should receive clinical attention and be incorporated into the development and optimization of preventive strategies for reducing oral ulcer incidence.

Occurrence of Cervical Spine Pain and Its Intensity in Young People with Temporomandibular Disorders

Background: The main aim of this cross-sectional study was to compare the occurrence and severity of cervical spine pain in young adults diagnosed with TMDs with a healthy control group (without TMDs). Methods: The study was conducted from June to July 2023. Inclusion criteria were age (18-30 years), cervical spine pain (for at least 1 month), and consent to participate in the study. The study was conducted based on RDC/TMD protocol, an original questionnaire, and a physiotherapeutic examination focused on detecting TMDs. The cervical pain level was assessed using the Visual Analogue Scale (VAS). Thus, a total of 95 subjects were registered for the trials, 51 people (53.7%) constituted the control group (without TMDs), while 44 (46.3%) people constituted the study group (with TMDs). Results: The mean age of people participating in the study was 22.2 ± 2.2 years in the study group and 22.5 ± 3.1 years in the control group. The largest group was people aged 21-25 (n = 51 people, 53.7%). Patients from the study group more often experienced pain in the stomatognathic system during palpation (both in the muscle, joint, and musculoskeletal groups) and had reduced mobility of the temporomandibular joints in every movement (p < 0.001). People from the study group were also characterized by less mobility of the cervical spine (p < 0.05), apart from extension movement (p > 0.05). The analysis showed that of the 95 people participating in the study, 85.4% reported problems in the cervical spine area (n = 81), of which almost all people in the study group struggled with this problem (n = 43, 97.7%). It was found that cervical spine pain was significantly more common in people with TMDs (p < 0.05, chi2 = 10.118, df = 1, rc = 0.31). The level of pain was significantly higher in people from the study group (p < 0.001, chi2 = 45.765, df = 4, rc = 0.57). Conclusions: Our research has shown that the occurrence of cervical spine pain is more common in the group of young people with temporomandibular disorders (TMDs). In young people, this problem is rarely recognized and properly treated.

Serotonin Transporter (5-Hydroxytryptamine Transporter, SERT, SLC6A4) and Sodium-dependent Reuptake Inhibitors as Modulators of Pain Behaviors and Analgesic Responses

The serotonin transporter (5-hydroxytryptamine transporter [5-HTT], Serotonin Transporter (SERT), SLC6A4) modulates the activity of serotonin via sodium-dependent reuptake. Given the established importance of serotonin in the control of pain, 5-HTT has received much interest in studies of pain states and as a pharmacological target for serotonin reuptake inhibitors (SRIs). Animal models expressing varying levels of 5-HTT activity show marked differences in pain behaviors and analgesic responses, as well as many serotonin-related physiological effects. In humans, functional nucleotide variations in the SLC6A4 gene, which encodes the serotonin transporter 5-HTT, are associated with certain pathologic pain conditions and differences in responses to pharmacological therapy. These findings collectively reflect the importance of 5-HTT in the intricate physiology and management of pain, as well as the scientific and clinical challenges that need to be considered for the optimization of 5-HTT-related analgesic therapies. PERSPECTIVE: The serotonin transporter 5-HTT/SCL6A4 is sensitive to pharmacological SRIs. Experimental studies on the physiological functions of serotonin, as well as genetic mouse models and clinical phenotype/genotype correlations of nucleotide variation in the human 5-HTT/SCL6A4 gene, provide new insights for the use of SRIs in chronic pain management.

The association of gene polymorphisms in catechol-O'methyltransferase (COMT) and β2-adrenergic receptor (ADRB2) with temporomandibular joint disorders

OBJECTIVE

Temporomandibular disorder (TMD) has a multifactorial etiology that includes environmental, psychological, and genetic factors. This study aimed to evaluate the possible relationship between polymorphisms in Catechol-O-methyltransferase (COMT) and β2-adrenergic receptor (ADRB2) genes with TMD.

DESIGN

This observational case-control study included 80 patients and 70 healthy controls. The diagnosis of TMD was made using the diagnostic criteria for TMD and the following TMD categories were used for the case group: muscular TMD and articular TMD (disc displacement and arthralgia). A genotyping study of gene polymorphisms in COMT (rs 9332377) and ADRB2 (rs20530449) was performed from genomic DNA isolated from blood. The chi-square test was used to analyze the relationships. P < 0.05 was accepted as a significant difference.

RESULTS

The polymorphic TT and CT genotype for COMT (rs rs9332377) was significantly higher in the articular TMD group while the non-polymorphic CC genotype was significantly lower in the articular TMD group (P < 0.05). Regarding ADRB2 (rs20530449), the polymorphic GG genotype was similarly considerably more common in the articular TMD group (p < 0.05). In addition, the T allele in the COMT (rs rs9332377) gene was found to be significantly higher in the articular TMD group (p < 0.05).

CONCLUSIONS

In the Turkish population, gene polymorphisms in COMT (rs9332377) and ADRB2 (rs2053044) were associated with articular TMD. This study supports the hypothesis that changes in COMT and ADRB2 genes may play a role in temporomandibular joint pain and predisposition to TMD.

Associations between Anxiety, Depression, Chronic Pain and Oral Health-Related Quality of Life, Happiness, and Polymorphisms in Adolescents' Genes

Adolescence is marked by changes and vulnerability to the emergence of psychological problems. This study aimed to investigate associations between anxiety/depression/chronic pain and oral health-related quality of life (OHRQoL)/happiness/polymorphisms in the COMT, HTR2A and FKBP5 genes in Brazilian adolescents. A cross-sectional study was conducted with ninety adolescents 13 to 18 years. Anxiety, depression and chronic pain were evaluated using the RDC/TMD. The Oral Health Impact Profile was used to assess oral OHRQoL. The Subjective Happiness Scale was used to assess happiness. Single-nucleotide polymorphisms in COMT (rs165656, rs174675), HTR2A (rs6313, rs4941573) and FKBP5 (rs1360780, rs3800373) were genotyped using the Taqman® method. Bivariate and multivariate logistic regression analyses were performed (p < 0.05). Chronic pain and depression were associated with feelings of happiness (p < 0.05). A significant inverse association was found between anxiety and OHRQoL (p = 0.004). The presence of minor allele C of COMT rs174675 was significantly associated with depression (p = 0.040). Brazilian adolescents with depression and chronic pain considers themselves to be less happy than others and those with anxiety are more likely to have a negative impact on OHRQoL. Moreover, the rs174675 variant allele in the COMT gene was associated with depressive symptoms in Brazilian adolescents.

Polymorphisms in the HTR2A and HTR3A Genes Contribute to Pain in TMD Myalgia

Background: The aim of this study was to investigate if single nucleotide polymorphisms (SNPs) related to monoaminergic neurotransmission, in particular the serotonergic pathway, contribute to pain perception in patients with temporomandibular disorder (TMD) myalgia and if there is a correlation to jaw function as well as psychosocial factors such as stress, anxiety and depression.

Materials and Methods: One hundred and seventeen individuals with TMD myalgia were included. A venous blood or saliva sample was taken for genetic analyses and genotyped regarding HTR2A (rs9316233) HTR3A (rs1062613), HTR3B (rs1176744), SERT (5-HTTLPR) and COMT (rs4680). A clinical examination according to Diagnostic Criteria for TMD (DC/TMD) was performed and axis II data (psychosocial factors) were compared between participants with different genotypes for each gene using Kruskall–Wallis test. The characteristic pain intensity (CPI) was tested for correlations to scores for the Perceived Stress Scale, Generalized Anxiety Disorder, and Patient Health Questionnaires using Spearman's rank correlation test with Bonferroni correction for multiple testing. To further explore data factor analysis was performed to identify latent factors associated to the outcome variables.

Results: Participants carrying at least one copy of the rare allele of the HTR2A (rs9316233) and HTR3A (rs1062613) had higher CPI compared with the participants with the homozygous common genotype (P = 0.042 and P = 0.024, respectively). Correlation analyses showed several significant positive correlations between CPI on one hand, and self-reported psychosocial distress and jaw function on the other hand for several genotypes that mostly were weak to moderate. The factor analysis identified two latent variables. One was positively correlated to the HTR3B gene, jaw function and self-reported parafunctions, and the other was positively correlated to psychological distress and negatively correlated to SERT.

Conclusion: Taken together, the polymorphism rs1062613 in the HTR3A gene contributes to pain intensity in TMD myalgia. This together with positive interactions between pain variables and psychological factors in genotypes strengthens that pain and psychological distress are related. Further research is needed to explore this as well as the influence of gene-to-gene interactions on pain and psychological distress.

TMD in Females with Menstrual Disorders

BACKGROUND

Temporomandibular disorders (TMD) are a common reason for patients to present at dental offices. The majority of people with TMD are women between the age of 20 and 40 years. The purpose of this study was to assess the types and prevalence of temporomandibular disorders in female patients of reproductive age with menstrual disorders.

MATERIALS AND METHODS

The study involved 65 females of reproductive age (18-40 years, an average of 28.00 ± 6.27 years). The women who qualified for the study were patients of the University Center for Maternal and Newborn's Health hospitalized because of infertility or menstrual cycle disorders. Women with confirmed estrogen metabolism disorders participated in a clinical study with the use of Diagnostic Criteria for Temporomandibular Disorders (DC/TMD).

RESULTS

In the studied female patients with menstrual disorders, temporomandibular disorders (92.3%) were frequent occurrences. The most common type was intra-articular joint disorders (68%). Other reported complaints included masticatory muscle pain (44.62%), and degenerative joint diseases (12.3%).

CONCLUSIONS

1. In women with menstrual disorders, TMD may exist. 2. In women with TMD symptoms, their medical history should be extended to include the diagnosis of female hormone disorders.

Genetic Polymorphisms in Serotonin Transporter (5HTT) and Catechol-O-Methyltransferase (COMT) On Dental Implant Loss-Pilot Project

The article's abstract is not available.

Is catechol-O-methyltransferase gene associated with temporomandibular disorders? A systematic review and meta-analysis

BACKGROUND

Temporomandibular disorder (TMD) is a condition, in which multiple factors act synergistically to determine the outcome of the disorder.

AIM

A systematic review and meta-analysis was conducted to evaluate the association between genetic polymorphisms in catechol-O-methyltransferase (COMT) and TMD.

DESIGN

Observational studies that investigated this association were included. The risk of bias and study quality were evaluated according to the Newcastle-Ottawa tool. The meta-analysis was performed for each polymorphism associated with TMD signs and symptoms.

RESULTS

A total of 1903 articles were identified. Ten remained in the qualitative analysis: six were classified as low risk of bias and four with moderate risk of bias, and three were included in the meta-analysis. The polymorphism rs6269, in the genotypic model (0.65; CI = 0.44-0.97; P = .04) and in the allelic model (0.73; CI = 0.54-0.98; P = .04), was associated with myofascial pain. The rs9332377 was associated with myofascial pain in the genotypic model (2.69; CI = 1.51-4.76; P = .0007) and in the allelic model (1.46; CI = 1.01-2.13; P = .05) and with painful TMD in the genotypic model (2.08; CI = 1.27-3.40; P = .004) and in the allelic model (1.34 CI = 0.98-1.82; P = .06).

CONCLUSION

The polymorphisms in COMT were significantly associated with TMD.

Prevalence of symptoms of temporomandibular disorders, oral behaviors, anxiety, and depression in Dentistry students during the period of social isolation due to COVID-19

Temporomandibular dysfunction (TMD), anxiety, and depression are disorders that, due to the current lifestyle, are affecting an increasing portion of the population. Investigating the prevalence of the symptoms of these disorders during the quarantine due to the coronavirus 2019 pandemic (COVID-19) is important to outline clinical strategies for patient care.

Insights for temporomandibular disorders management: From psychosocial factors to genetics-A case report

AIMS

This case report aimed to discuss the multifactorial etiology and also the management of temporomandibular disorders (TMD) by addressing important associated psychosocial and biological factors, emphasizing the interaction between these factors and a probable genetic predisposition.

METHODS AND RESULTS

A 21-year-old female patient was evaluated according to Research Diagnostic Criteria for TMD and diagnosed with arthralgia, myofascial pain, disc displacement without reduction, and temporomandibular joint (TMJ) degenerative disease. TMJ alterations were confirmed through magnetic resonance imaging and cone-beam computed tomography. Pressure pain threshold of masticatory structures was evaluated using a pressure algometer. Sleep bruxism, poor sleep quality, migraine with aura, mild anxiety, and history of facial trauma were also identified through anamnesis and clinical examination. Following this, genetic analysis was performed to evaluate the presence of single nucleotide polymorphisms (SNPs) already associated with TMD: SNP COMT Val¹⁵⁸ Met (rs4680), MMP1-1607 (rs1799750), and tumor necrosis factor alpha-308 (rs1800629), which were all present. A personalized treatment for TMD management was performed, and it included self-management programs, occlusal appliance therapy, pharmacotherapy, anxiety management, and stress control. An 8-year follow-up demonstrated long-term stabilization of TMJ degenerative disease.

CONCLUSION

Genetic evaluation, added to anamnesis and clinical examination, could be useful for TMD prognosis and management.

COMT rs4818, pain sensitivity and duration, and alveolar bone grafting of oral clefts

PURPOSE

Verifying whether the mutation in COMT rs4818 could be involved in pain modulation.

METHODS

Thirty-two individuals born with cleft lip and palate that underwent bone graft from the iliac crest bone were assessed at 12, 24, 48, 72 h, and 7 days regarding their pain experience using a visual analogic scale. DNA from each participant was collected from saliva samples, and genotyping of rs4818 was performed using TaqMan chemistry. Overrepresentation of rs4818 alleles was tested using chi-square or Fisher's exact tests with an alpha of 0.05.

RESULTS

Of the 32 individuals, eighteen reported long pain duration, nine reported high pain intensity, and fourteen low pain intensity up to 48 h. No differences were found in the distribution of individuals depending on the reported pain by sex (p = 0.12), age (p = 0.42), or cleft type (p = 0.5). The distribution of COMT r4818 alleles was different depending on the intensity and duration of pain. Carriers of the C wild-type allele were four times more likely to show high pain intensity and duration (odds ratio = 4.29, 95% confidence interval 1.13-16.18), meaning that the G variant allele is protective.

CONCLUSION

COMT rs4818 is associated with postoperative pain after alveolar bone grafting.

Rs9303628 and rs2054847 of SLC6A4 are protective factors for the onset of lifelong premature ejaculation among the Chinese population

The purpose of this study was to investigate whether the polymorphisms of SLC6A4 gene affect the occurrence of lifelong premature ejaculation (LPE). In this case-control study, Agena MassARRAY was used to genotype SLC6A4 polymorphisms of 91 LPE patients and 362 controls. Then, genetic model and haplotype analysis were utilised to explore the correlation between SLC6A4 polymorphisms and LPE risk. The results showed that allele T, genotype T/T and C/T-T/T of rs9303628 were significantly correlated with a decreased risk of LPE in allele (p = .009), co-dominant (p = .025) and dominant (p = .014) model respectively. Allele T and genotype C/T-T/T of rs2054847 reduced the risk of LPE in co-dominant (p = .015) and dominant (p = .030) models respectively. Furthermore, there was a significant correlation between A_rs9303628 C_rs2054847 haplotype and the decreased the risk of LPE (p = .010). In conclusion, this study firstly proved that the presence of rs9303628 and rs2054847 in SLC6A4 gene was a protective factor for the occurrence of LPE in the Chinese Han population.

Pharmacogenomics of Pain Management: The Impact of Specific Biological Polymorphisms on Drugs and Metabolism

PURPOSE OF REVIEW

Pain is multifactorial and complex, often with a genetic component. Pharmacogenomics is a relative new field, which allows for the development of a truly unique and personalized therapeutic approach in the treatment of pain.

RECENT FINDINGS

Until recently, drug mechanisms in humans were determined by testing that drug in a population and calculating response averages. However, some patients will inevitably fall outside of those averages, and it is nearly impossible to predict who those outliers might be. Pharmacogenetics considers a patient's unique genetic information and allows for anticipation of that individual's response to medication. Pharmacogenomic testing is steadily making progress in the management of pain by being able to identify individual differences in the perception of pain and susceptibility and sensitivity to drugs based on genetic markers. This has a huge potential to increase efficacy and reduce the incidence of iatrogenic drug dependence and addiction. The streamlining of relevant polymorphisms of genes encoding receptors, transporters, and drug-metabolizing enzymes influencing the pain phenotype can be an important guide to develop safe new strategies and approaches to personalized pain management. Additionally, some challenges still prevail and preclude adoption of pharmacogenomic testing universally. These include lack of knowledge about pharmacogenomic testing, inadequate standardization of the process of data handling, questionable benefits about the clinical and financial aspects of pharmacogenomic testing-guided therapy, discrepancies in clinical evidence supporting these tests, and doubtful reimbursement of the tests by health insurance agencies.