Incidence Of Temporomandibular Disorder Research Articles

Anxiety associated painful temporomandibular disorders in Peruvian dental students during the major waves of COVID-19 infection: A cohort study

Abstract Aim: During the major waves of coronavirus disease 2019 (COVID-19) infection, Peru had the highest case fatality rate in the world. This situation may have caused psychological conditions with somatic consequences in students who were susceptible to infection due to exposure to infected patients. The present study was designed to investigate the association between anxiety levels and painful temporomandibular disorders in dental students from two Peruvian provinces during the major waves of COVID-19 infection. Materials and Methods: The study conducted was both longitudinal and analytical. The total population consisted of 558 dental students from Peru, with 314 from Chimbote and 244 from Trujillo. No sample size calculation was necessary as the entire student population was invited to participate. Of the 366 students who initially joined the closed cohort, only 204 remained at the end of the study. During the first and second waves of COVID-19 infections, the Zung anxiety diagnostic test and the diagnostic criteria for painful temporomandibular disorder (DC/TMD) triage questionnaire were used to assess anxiety levels. The study also evaluated variables such as sex, age, marital status, academic year of study, area of residence, housing type, and occupation. The study employed statistical analysis to determine the relative risk (RR) of painful TMD incidence during the first and second waves of COVID-19 infections. A logit model was also used to determine the presence of painful TMD, with odds ratio (OR) as the measure. The statistical significance level was set at P < 0.05. Results: During the initial wave of COVID-19 infections, 50% (95% CI: 43.1–56.9%) of the 204 students experienced anxiety, while 26.5% (95% CI: 20.4–32.6%) reported TMD. Furthermore, those who exhibited anxiety were eight times more likely to develop TMD (OR = 8.88, 95% CI: 3.95 - 19.97). In the second wave, 62.3% (95% CI: 55.6–69.0%) of students reported anxiety, and 86.3% (95% CI: 81.6–91.0%) reported TMD. Additionally, individuals with anxiety were found to have a significantly higher likelihood of developing painful TMD, with a nine-fold increase in risk (OR = 9.87, 95% CI: 5.08–19.19). The cohort of students exposed and not exposed to anxiety during the first and second waves of COVID-19 infection showed a 4.58 times higher risk (95% CI: 2.61–8.03) of developing painful TMD due to anxiety. Conclusion: Between the first and second waves of COVID-19 infection, the prevalence of anxiety and painful temporomandibular disorder (TMD) increased among dental students. This establishes anxiety as a significant predisposing factor for the development of painful TMD over time.

Association of Serum Vitamin D Level with Temporomandibular Disorder Incidence: A Retrospective, Multi-Center Cohort Study Using Six Hospital Databases.

The relationship between serum vitamin D levels and temporomandibular disorders (TMDs) remains unclear. Therefore, this study aimed to investigate the association between serum 25-hydroxyvitamin D (25[OH]D) levels and TMD incidence using large-scale health data. Clinical data from the electronic health records of six secondary or tertiary hospitals in Korea were used to evaluate the relationship between serum 25(OH)D levels and TMD incidence. The data were converted to the Observational Medical Outcomes Partnership Common Data Model. A cohort study was designed using the Cox proportional hazards model to examine the hazard ratio (HR) of TMD development after propensity score matching (PSM). An aggregate meta-analysis of the HR was subsequently performed. After 1:4 PSM, a target group with deficient 25(OH)D levels (<20 ng/mL) (N = 34,560) and comparator group with non-deficient 25(OH)D levels (≥20 ng/mL) (N = 47,359) were pooled from six hospital databases. HR meta-analysis demonstrated a significant association between deficient 25(OH)D levels and TMD incidence (pooled HR: 1.50; 95% confidence interval: 1.07-2.12). In conclusion, deficient 25(OH)D levels were found to be associated with an increased TMD risk. Therefore, vitamin D deficiency is a potential risk factor for TMD development.

Associations among temporomandibular disorder, headache, shoulder pain, craniofacial morphology, and premature contacts in female children and adolescents with malocclusion

ABSTRACT Purpose Orthodontic patients frequently exhibit signs and symptoms of temporomandibular disorder (TMD) in combination with symptoms around the stomatognathic region (i.e. headache). Although maxillofacial morphology and malocclusion have been widely investigated as risk factors for TMD and headache, their relationship remains unclear and functional factors have not been verified. This study investigated associations among TMD, headache, craniofacial morphology, and premature contacts in female children and adolescents with malocclusion. Materials and methods One hundred twenty female children and adolescents (mean age, 11.4 ± 2.5 years) who sought orthodontic treatment were randomly selected from a cohort of orthodontic patients. The patients were divided into three groups (no condition, at least one condition, ≥ 2 conditions: TMD, headache, and/or shoulder pain). Premature contacts were determined using the functional wax bite method; craniofacial morphology was analysed using lateral cephalometric radiographs. The χ2 test, Tukey test, and ordered logistic regression were used for statistical analysis. Results Patients with TMD and headache had a steep mandibular plane angle (odds ratio = 1.11), but there were no significant differences among groups in other craniofacial morphology parameters. Patients with premature contacts had a higher incidence of combined TMD and headache (odds ratio = 7.72). Premature contacts more strongly contributed to pathogenesis than did mandibular plane angle or age. Conclusion TMD and headache are associated with both craniofacial morphology and premature contacts.

Benefits and Risks of Orthodontic Treatment: A Systematic Review

Background: Malocclusion is one of the main problems of oral and dental health, ranked third after caries and periodontal diseases. In Asian population, the percentage of class II and III Angle malocclusion is 21.42% and 5.76% respectively. Thus, orthodontic treatment is still needed by the people. However, not every patient knows the potential risks that orthodontic treatment, and whether the treatment will bring them benefits they want to achieve. Purpose: this study aimed to describe benefits and risks of orthodontic treatment on the patient and operator through scooping review. Review(s): The search of literatures show that orthodontic treatment increases patient’s oral health related quality of life, reducing the risk of traumatic dental injuries in children with large overjet, and reducing the incident of muscle tenderness, and myofascial pain. However, orthodontic treatment poses the risk of damage to the teeth, oral and mucosal pain, speech problems, allergic reactions, and orthodontics relapse. Conclusion: Orthodontic treatment can provide benefits to patients’ oral health related quality of life, as well as reducing the incidence of temporomandibular disorder and traumatic dental injuries in children with large overjet. But these benefits must outweigh the risks that can occur in the patient such as teeth damage, oral and mucosal pain, speech problems, allergic reactions, and the probability of relapse must also be minimized.

Influência da qualidade das próteses totais na prevalência de disfunção temporomandibular

Abstract Introduction Temporomandibular disorder (TMD) involves the mastication and temporomandibular articulation muscles. Completely toothless patients with prostheses should be thoroughly assessed since edentulism causes damage that can lead to TMD onset. Objective This study aims to assess the effect of the technical quality of total prostheses (TPs) on TMD occurrence in patients with bimaxillary TPs. Material and method 154 patients responded to a questionnaire to obtain personal data, information regarding prostheses, anamnestic index for TMD, and the prosthesis quality index. Result Of the 154 patients examined, 64 (41.6%) had no TMD, 61 (39.6%) had mild TMD, 23 (14.9%) moderate, and only 6 (3.9%) showed severe TMD. As for the quality of total prosthesis, 78 (50.6%) completely toothless individuals had satisfactory TPs while 76 (49.4) presented unsatisfactory prostheses. Regarding the time using total prosthesis, around 50% of individuals with up to 10 years use presented some degree of TMD and 70% of individuals with over 10 years presented TMD. Conclusion Considering the methodology used and the population studied, we conclude that the quality of the TPs did not influence the incidence of TMD.

Bidirectional relationship between temporomandibular disorder and ankylosing spondylitis: a population-based cohort study.

This study aimed to determine the relation between temporomandibular disorder (TMD) and ankylosing spondylitis (AS) bidirectionally and ascertain the important comorbidities for AS occurrence in TMD patients. We conducted this population-based cohort study through Longitudinal Health Insurance Database, Taiwan. Study 1 investigated the risk of TMD in AS patients. Study 2 assessed the risk of AS in TMD patients. In total, 3204 AS patients and 12,816 age-matched and gender-matched comparisons were enrolled in study 1. The TMD incidence in the AS cohort was 2.88-fold higher when compared with the comparisons (1.54 vs. 0.53 per 10,000 person-years). After adjusting for age, gender, and comorbidity, the AS cohort had a 2.66-fold (95% CI = 1.79-3.97) increased risk of TMD occurrence (P < 0.0001). The second study recruited 4998 TMD patients and 19,991 age-matched and gender-matched comparisons. Both TMD and comparison cohorts showed similar AS risk (HR = 1.49, 95% CI = 0.91-2.43, P = 0.1108) in the adjusted model. Study 2 identified a 3.66-fold increased risk of AS occurrence in TMD patients with comorbidity, including parapsoriasis, rheumatoid arthritis, osteoporosis, Cushing's syndrome, and climacteric arthritis (P < 0.012). AS appears to significantly impact the occurrence of TMD. TMD might play a synergic role in AS development. Clinicians have to be vigilant about the increased risk of TMD in AS patients and take care of AS disease activity and prognosis. The symptoms and signs of TMD could be a predictor of AS in patients with the aforementioned comorbidities.

Pain Sensitivity Modifies Risk of Injury-Related Temporomandibular Disorder

This study evaluates contributions of jaw injury and experimental pain sensitivity to risk of developing painful temporomandibular disorder (TMD). Data were from the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) nested case-control study of incident painful TMD. Injury and subsequent onset of painful TMD were monitored prospectively for ≤5 y in a community-based sample of 409 US adults who did not have TMD when enrolled. At baseline, thermal-pressure and pinprick pain sensitivity, as potential effect modifiers, were measured using quantitative sensory testing. During follow-up, jaw injury from any of 9 types of potentially traumatic events was determined using quarterly (3-monthly) health update questionnaires. Study examiners classified incident painful TMD, yielding 233 incident cases and 176 matched controls. Logistic regression models, estimated incidence odds ratios (IORs), and 95% confidence limits (CLs) were used for the association between injury and subsequent onset of painful TMD. During follow-up, 38.2% of incident cases and 13.1% of controls reported 1 or more injuries that were 4 times as likely to be intrinsic (i.e., sustained mouth opening or yawning) as extrinsic (e.g., dental visits, whiplash). Injuries due to extrinsic events (IOR = 7.6; 95% CL, 1.6–36.2), sustained opening (IOR = 5.4; 95% CL, 2.4–12.2), and yawning (IOR = 3.4; 95% CL, 1.6–7.3) were associated with increased TMD incidence. Both a single injury (IOR = 6.0; 95% CL, 2.9–12.4) and multiple injuries (IOR = 9.4; 95% CL, 3.4,25.6) predicted greater incidence of painful TMD than events perceived as noninjurious (IOR = 1.9; 95% CL, 1.1–3.4). Injury-associated risk of painful TMD was elevated in people with high sensitivity to heat pain (IOR = 7.4; 95% CL, 3.1–18.0) compared to people with low sensitivity to heat pain (IOR = 3.9; 95% CL, 1.7–8.4). Jaw injury was strongly associated with elevated painful TMD risk, and the risk was amplified in subjects who had enhanced sensitivity to heat pain at enrollment. Commonly occurring but seemingly innocuous events, such as yawning injury, should not be overlooked when judging prognostic importance of jaw injury.

The Incidence of Signs and Symptoms of Temporomandibular Disorders Following Third Molar Surgery

Third molar surgery, a common dental procedure in Dental Faculty University Malaya, is known to pose many possible complications, one of which is temporomandibular disorder (TMD); a chronic pain concerning the joint apparatus, masticatory musculature and the associated muscle of head and neck region. This research aims (i) to examine the signs and symptoms of TMD following third molar surgery (ii) to study the surgical components of third molar surgery that contribute to the development of TMD (iii) to compare incidence of TMD between operative and non-operative group six months after third molar surgery. A descriptive longitudinal cohort study was conducted by recruiting twenty-two patients as subjects of an operative group, and twenty patients as subjects of a non-operative group. The operative group were examined at baseline, one week, one month, three months and six months after surgery. Each patient underwent a series of Diagnostic Criteria of TMD DC/TMD examination and history questionnaire. In the operative group, we found (i) increased incidence of trismus (92%), myofascial pain (69%) and clicking (77%) of the patient group at one week review (ii) two new incidences of signs and symptoms of TMD at final review (iii) no significant relationship between operator qualification to development of TMD (iv) no association between degree of impaction to development of TMD (v) no relationship between duration of procedures to development of TMD (vi) there is a significant difference in signs and symptoms of TMD between operative group and control group (p<0.005).

Disfunção temporomandibular e dor craniocervical em profissionais da área da enfermagem sob estresse no trabalho

RESUMO Objetivo: verificar a presença e severidade de Disfunção Temporomandibular, presença de cefaleia e cervicalgia e o limiar de dor muscular de músculos cervicais em profissionais de enfermagem sob estresse no trabalho. Métodos: 43 mulheres foram avaliadas quanto à presença e severidade de Disfunção Temporomandibular pelo instrumento Critérios de Diagnóstico para Pesquisa de Desordem Temporomandibular e pelo Índice Temporomandibular, respectivamente. Além disso, foram avaliadas quanto ao limiar de dor à pressão nos músculos cervicais por algometria e quanto à presença de cefaleia e cervicalgia. Resultados: disfunção Temporomandibular foi encontrada em 30,23% da amostra, com valor médio de escore de gravidade de 0,52. Entre as participantes com Disfunção Temporomandibular, 69,23% apresentavam depressão, 61,64% graduação I de dor crônica e Sintomas Físicos não Específicos incluindo e excluindo itens de dor em 46,15% e 61,64%, respectivamente. Cefaleia foi referida por 55,81% e cervicalgia por 60,47%. Não houve associação entre Disfunção Temporomandibular, cefaleia e cervicalgia. Os limiares de dor dos músculos cervicais apresentaram-se baixos tanto nos indivíduos com diagnóstico de Disfunção Temporomandibular quanto nos sem este diagnóstico, sem diferença significativa. O músculo esternocleidomastóideo apresentou-se com os menores limiares de dor à pressão. Conclusão: alta incidência de Disfunção Temporomandibular, cefaleia e cervicalgia foram detectadas nesta amostra. Disfunção Temporomandibular não influenciou a presença de cefaleia e/ou cervicalgia. A alta frequência de dor cervical e os baixos limiares de dor no músculo esternocleidomastóideo em todas as participantes demonstram o comprometimento dos músculos cervicais, resultante de possíveis posturas inadequadas e tensão muscular relacionadas ao estresse.

Subjective Sleep Quality Deteriorates Before Development ofPainful Temporomandibular Disorder.

There is good evidence that poor sleep quality increases risk of painful temporomandibular disorder (TMD). However, little is known about the course of sleep quality in the months preceding TMD onset, and whether the relationship is mediated by heightened sensitivity to pain. The Pittsburgh Sleep Quality Index was administered at enrollment into the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) prospective cohort study. Thereafter the Sleep Quality Numeric Rating Scale was administered every 3months to 2,453 participants. Sensitivity to experimental pressure pain and pinprick pain stimuli was measured at baseline and repeated during follow-up of incident TMD cases (n=220) and matched TMD-free controls (n=193). Subjective sleep quality deteriorated progressively, but only in those who subsequently developed TMD. A Cox proportional hazards model showed that risk of TMD was greater among participants whose sleep quality worsened during follow-up (adjusted hazard ratio=1.73, 95% confidence limits=1.29, 2.32). This association was independent of baseline measures of sleep quality, psychological stress, somatic awareness, comorbid conditions, nonpain facial symptoms, and demographic characteristics. Poor baseline sleep quality was not significantly associated with baseline pain sensitivity or with subsequent change in pain sensitivity. Furthermore the relationship between sleep quality and TMD incidence was not mediated via baseline pain sensitivity or change in pain sensitivity. Subjective sleep quality deteriorates progressively before the onset of painful TMD, but sensitivity to experimental pain does not mediate this relationship. Furthermore, the relationship is independent of potential confounders such as psychological stress, somatic awareness, comorbid conditions, nonpain facial symptoms, and various demographic factors.

Parameter estimation in Cox models with missing failure indicators and the OPPERA study.

In a prospective cohort study, examining all participants for incidence of the condition of interest may be prohibitively expensive. For example, the "gold standard" for diagnosing temporomandibular disorder (TMD) is a physical examination by a trained clinician. In large studies, examining all participants in this manner is infeasible. Instead, it is common to use questionnaires to screen for incidence of TMD and perform the "gold standard" examination only on participants who screen positively. Unfortunately, some participants may leave the study before receiving the "gold standard" examination. Within the framework of survival analysis, this results in missing failure indicators. Motivated by the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study, a large cohort study of TMD, we propose a method for parameter estimation in survival models with missing failure indicators. We estimate the probability of being an incident case for those lacking a "gold standard" examination using logistic regression. These estimated probabilities are used to generate multiple imputations of case status for each missing examination that are combined with observed data in appropriate regression models. The variance introduced by the procedure is estimated using multiple imputation. The method can be used to estimate both regression coefficients in Cox proportional hazard models as well as incidence rates using Poisson regression. We simulate data with missing failure indicators and show that our method performs as well as or better than competing methods. Finally, we apply the proposed method to data from the OPPERA study.

COMT Diplotype Amplifies Effect of Stress on Risk of Temporomandibular Pain

When measured once, psychological stress predicts development of painful temporomandibular disorder (TMD). However, a single measurement fails to characterize the dynamic nature of stress over time. Moreover, effects of stress on pain likely vary according to biological susceptibility. We hypothesized that temporal escalation in stress exacerbates risk for TMD, and the effect is amplified by allelic variants in a gene, catechol-O-methyltransferase (COMT), regulating catechol neurotransmitter catabolism. We used data from the Orofacial Pain: Prospective Evaluation and Risk Assessment prospective cohort study of 2,707 community-dwelling adults with no lifetime history of TMD on enrollment. At baseline and quarterly periods thereafter, the Perceived Stress Scale (PSS) measured psychological stress. Genotyped DNA from blood samples determined COMT diplotypes. During follow-up of 0.25 to 5.2 y, 248 adults developed examiner-verified incident TMD. PSS scores at baseline were 20% greater (P < 0.001) in adults who developed incident TMD compared with TMD-free controls. Baseline PSS scores increased by 9% (P = 0.003) during follow-up in cases but remained stable in controls. This stress escalation was limited to incident cases with COMT diplotypes coding for low-activity COMT, signifying impaired catabolism of catecholamines. Cox regression models confirmed significant effects on TMD hazard of both baseline PSS (P < 0.001), modeled as a time-constant covariate, and change in PSS (P < 0.001), modeled as a time-varying covariate. Furthermore, a significant (P = 0.04) interaction of COMT diplotype and time-varying stress showed that a postbaseline increase of 1.0 standard deviation in PSS more than doubled risk of TMD incidence in subjects with low-activity COMT diplotypes (hazard ratio = 2.35; 95% confidence limits: 1.66, 3.32), an effect not found in subjects with high-activity COMT diplotypes (hazard ratio = 1.42; 95% confidence limits: 0.96, 2.09). Findings provide novel insights into dynamic effects of psychological stress on TMD pain, highlighting that effects are most pronounced in individuals whose genetic susceptibility increases responsiveness to catecholamine neurotransmitters.

Pressure pain thresholds fluctuate with, but do not usefully predict, the clinical course of painful temporomandibular disorder

Central sensitization elicits pain hypersensitivity and is thought to be causally implicated in painful temporomandibular disorder (TMD). This causal inference is based on cross-sectional evidence that people with TMD have greater sensitivity than controls to noxious stimuli. We tested this inference in the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) prospective cohort study of 3258 adults with no lifetime history of TMD when enrolled (visit 1). During 5years of follow-up, 1 group labeled “persistent TMD cases” (n=72) developed first-onset TMD by visit 2 that persisted ⩾6months until visit 3. Another group labeled “transient TMD cases” (n=75) developed first-onset TMD at visit 2, which resolved by visit 3. Randomly sampled “controls” (n=126) remained TMD-free throughout all 3 visits. At each visit, pressure pain thresholds (PPTs) were measured by algometry at 10 cranial and bodily sites. In persistent TMD case patients, mean PPTs reduced 43kPa (P<.0001) between visits 1 and 2 and thereafter did not change significantly. In transient TMD case patients, mean PPTs reduced 41kPa (P<.001) between visits 1 and 2, and then increased 20kPa (P<.001) by visit 3. These patterns were similar after excluding cranial sites symptomatic for TMD. Importantly, visit 1 PPTs had no clinically useful prognostic value in predicting first-onset TMD (odds ratio [OR]=1.07, P=.15). Among first-onset case patients, visit 2 PPTs were modest predictors of persistent TMD (OR=1.36, P=.002). In this longitudinal study, PPTs reduced when TMD developed then rebounded when TMD resolved. However, premorbid PPTs poorly predicted TMD incidence, countering the hypothesis that PPTs signify mechanisms causing first-onset TMD.

Multivariable Modeling of Phenotypic Risk Factors for First-Onset TMD: The OPPERA Prospective Cohort Study

Incidence of temporomandibular disorder (TMD) was predicted with multivariable models that used putative risk factors collected from initially TMD-free individuals in the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study. The 202 baseline risk factors included sociodemographic and clinical characteristics, measures of general health status, experimental pain sensitivity, autonomic function, and psychological distress. Study participants (n = 2,737) were then followed prospectively for a median of 2.8 years to ascertain cases of first-onset TMD. Lasso regression and random forest models were used to predict incidence of first-onset TMD using all of the aforementioned measures. Variable importance scores identified the most important risk factors, and their relationship with TMD incidence was illustrated graphically using partial dependence plots. Two of the most important risk factors for elevated TMD incidence were greater numbers of comorbid pain conditions and greater extent of nonspecific orofacial symptoms. Other important baseline risk factors were preexisting bodily pain, heightened somatic awareness, and greater extent of pain in response to examiners' palpation of the head, neck, and body. Several demographic variables persisted as risk factors even after adjusting for other OPPERA variables, suggesting that environmental variables not measured in OPPERA may also contribute to first-onset TMD. PerspectiveMultivariable methods were used to identify the most important predictors of first-onset TMD in the OPPERA study. Important variables included comorbid pain conditions, preexisting pain, and somatic awareness. Demographic characteristics, which probably reflect environmental variables not measured in OPPERA, also appear to play an important role in the etiology of TMD.

General Health Status and Incidence of First-Onset Temporomandibular Disorder: The OPPERA Prospective Cohort Study

Temporomandibular disorder (TMD) overlaps with other health conditions, but no study has examined which of these conditions increase the risk of developing first-onset TMD. The authors prospectively evaluated the relationship between health status at enrollment and subsequent incidence of TMD in 2,722 men and women. Participants aged 18 to 44 years had no history of TMD and were clinically free of TMD when enrolled in 2006 to 2008 at 4 U.S. study sites in the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) prospective cohort study. First-onset examiner-classified TMD developed in 260 people over a median 2.8 years of follow-up. Cox regression estimated the association between health conditions and TMD incidence while accounting for potential confounders. Incidence of first-onset TMD was 50% higher for people with low back pain (adjusted hazard ratio [AHR] = 1.50, 95% confidence limits [CLs]: 1.08, 2.10) and 75% higher for people with genital pain symptoms (AHR = 1.75, 95% CLs = 1.04, 2.93) than people without a history of these pain disorders. Digit ratio, a marker of intrauterine exposure to sex hormones, was significantly associated with TMD incidence. Other independent predictors of first-onset TMD were sleep disturbance and cigarette smoking. These findings reveal multiple influences of health status on incidence of first-onset TMD. PerspectiveThis article examines health conditions that commonly overlap with TMD to determine which ones predict first-onset TMD. A history of low back pain and genital pain conditions at baseline were important predictors. Novel findings were that disrupted sleep and conditions in utero may increase incidence of first-onset TMD.

Signs and Symptoms of First-Onset TMD and Sociodemographic Predictors of Its Development: The OPPERA Prospective Cohort Study

Although cross-sectional studies of temporomandibular disorder (TMD) often report elevated prevalence in young women, they do not address the risk of its development. Here we evaluate sociodemographic predictors of TMD incidence in a community-based prospective cohort study of U.S. adults. Symptoms and pain-related disability in TMD cases are also described. People aged 18 to 44 years with no history of TMD were enrolled at 4 study sites when they completed questionnaires about sociodemographic characteristics. During the median 2.8-year follow-up period, 2,737 participants completed quarterly screening questionnaires. Those reporting symptoms were examined clinically and 260 had first-onset TMD. Additional questionnaires asked about severity and impact of their symptoms. Univariate and multivariable Cox regression models quantified associations between sociodemographic characteristics and TMD incidence. First-onset TMD developed in 3.9% of participants per annum, typically producing mild to moderate levels of pain and disability in cases. TMD incidence was positively associated with age, whereas females had only slightly greater incidence than males. Compared to whites, Asians had lower TMD incidence whereas African Americans had greater incidence, although the latter was attenuated somewhat after adjusting for satisfaction with socioeconomic circumstances. PerspectiveIn this study of 18- to 44-year-olds, TMD developed at a higher rate than reported previously for similar age groups. TMD incidence was positively associated with age but weakly associated with gender, thereby differing from demographic patterns of prevalence found in some cross-sectional studies. Experiences related to aging merit investigation as etiologic influences on development of TMD.

Clinical Orofacial Characteristics Associated With Risk of First-Onset TMD: The OPPERA Prospective Cohort Study

Case-control studies have documented clinical manifestations of chronic temporomandibular disorder (TMD), whereas clinical predictors of TMD development are largely unknown. We evaluated 41 clinical orofacial characteristics thought to predict first-onset TMD in a prospective cohort study of U.S. adults aged 18 to 44 years. During the median 2.8-year follow-up period, 2,737 people completed quarterly screening questionnaires. Those reporting symptoms were examined and 260 people were identified with first-onset TMD. Univariate and multivariable Cox regression models quantified associations between baseline clinical orofacial measures and TMD incidence. Significant predictors from baseline self-report instruments included oral parafunctions, prior facial pain and its life-impact, temporomandibular joint noises and jaw locking, and nonspecific orofacial symptoms. Significant predictors from the baseline clinical examination were pain on jaw opening and pain from palpation of masticatory, neck, and body muscles. Examiner assessments of temporomandibular joint noise and tooth wear facets did not predict incidence. In multivariable analysis, nonspecific orofacial symptoms, pain from jaw opening, and oral parafunctions predicted TMD incidence. The results indicate that only a few orofacial examination findings influenced TMD incidence, and only to a modest degree. More pronounced influences were found for self-reported symptoms, particularly those that appeared to reflect alterations to systems beyond the masticatory tissues. PerspectiveOPPERA's prospective cohort study identifies predictors of first-onset TMD comprising self-reported orofacial symptoms and examination findings. The results suggest a complex pattern of TMD etiology that is influenced by disorders locally, in masticatory tissues, and systemically, in pain-regulatory systems.

Pain Sensitivity and Autonomic Factors Associated With Development of TMD: The OPPERA Prospective Cohort Study

Multiple studies report that individuals with chronic temporomandibular disorder (TMD) have enhanced sensitivity to experimental pain. Additionally, chronic TMD cases show altered autonomic function, including elevated heart rate and reduced heart rate variability. However, causal inferences regarding the association between TMD and pain sensitivity and autonomic function cannot be drawn from these cross-sectional observations. The prospective Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study examines whether measures of pain sensitivity or cardiac autonomic function provide predictive value in TMD incidence. A cohort of 2,737 initially TMD-free participants was followed for up to 5.2 years, during which time 260 developed first-onset TMD. Fourteen of 39 experimental pain measures produced significant hazard ratios, such that greater pain sensitivity was associated with greater TMD incidence. A single autonomic measure—heart rate at rest—was also associated significantly with greater TMD incidence. In contrast, using the same measures of pain sensitivity and cardiac autonomic function, we previously reported a larger group of variables that was significantly associated with chronic TMD in the OPPERA case-control study. Future studies should investigate whether premorbid pain sensitivity or autonomic function more specifically predicts risk of developing chronic TMD than first-onset TMD. PerspectiveOur previous case-control studies showed that associations with both pain sensitivity and cardiac autonomic function are profound in chronic TMD cases. Here we show that some measures of enhanced pain sensitivity contribute modestly to the risk of developing TMD whereas autonomic dysregulation appears to confer little or no risk for TMD incidence.

Genetic Variants Associated With Development of TMD and Its Intermediate Phenotypes: The Genetic Architecture of TMD in the OPPERA Prospective Cohort Study

Genetic risk factors are believed to combine with environmental exposures and contribute to the risk of developing temporomandibular disorder (TMD). In this prospective cohort study, 2,737 people without TMD were assessed for common genetic variation in 358 genes known to contribute to nociceptive pathways, inflammation, and affective distress. During a median follow-up period of 2.8 years, 260 people developed first-onset TMD. Hazard ratios were computed as measures of association between 2,924 single-nucleotide polymorphisms and TMD incidence. After correction for multiple testing, no single single-nucleotide polymorphism was significantly associated with risk of onset TMD. However, several single-nucleotide polymorphisms exceeded Bonferroni correction for multiple comparison or false discovery rate thresholds (.05, .1, or .2) for association with intermediate phenotypes shown to be predictive of TMD onset. Nonspecific orofacial symptoms were associated with voltage-gated sodium channel, type I, alpha subunit (SCN1A, rs6432860, P = 2.77 × 10−5) and angiotensin I–converting enzyme 2 (ACE2, rs1514280, P = 4.86 × 10−5); global psychological symptoms with prostaglandin-endoperoxide synthase 1 (PTGS1, rs3842803, P = 2.79 × 10−6); stress and negative affectivity with amyloid-β (A4) precursor protein (APP, rs466448, P = 4.29 × 10−5); and heat pain temporal summation with multiple PDZ domain protein (MPDZ, rs10809907, P = 3.05 × 10−5). The use of intermediate phenotypes for complex pain diseases revealed new genetic pathways influencing risk of TMD. PerspectiveThis article reports the findings of a large candidate gene association study of first-onset TMD and related intermediate phenotypes in the OPPERA Study. Although no genetic markers predicted TMD onset, several genetic risk factors for clinical, psychological, and sensory phenotypes associated with TMD onset were observed.

Summary of Findings From the OPPERA Prospective Cohort Study of Incidence of First-Onset Temporomandibular Disorder: Implications and Future Directions

Papers in this issue investigate when and how putative risk factors influence development of first-onset, painful temporomandibular disorder (TMD). The results represent first findings from the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) prospective cohort study that monitored 2,737 men and women aged 18 to 44 years recruited at 4 U.S. study sites. During a median 2.8-year follow-up period, 260 participants developed TMD. The average incidence rate of 4% per annum was influenced by a broad range of phenotypic risk factors including sociodemographic characteristics, health status, clinical orofacial factors, psychological functioning, pain sensitivity, and cardiac autonomic responses. A novel method of multivariable analysis used random forest models to simultaneously evaluate contributions of all 202 phenotypic variables. Variables from the health status domain made the greatest contribution to TMD incidence, followed closely by psychological and clinical orofacial domains. However, only a few measures of pain sensitivity and autonomic function contributed to TMD incidence, and their effects were modest. Meanwhile, age and study site were independent predictors of TMD incidence, even after controlling for other phenotypes. Separate analysis of 358 genes that regulate pain found several novel genetic associations with intermediate phenotypes that, themselves, are risk factors for TMD, suggesting new avenues to investigate biological pathways contributing to TMD. PerspectiveCollectively, the papers in this issue demonstrate that TMD is a complex disorder with multiple causes consistent with a biopsychosocial model of illness. It is a misnomer and no longer appropriate to regard TMD solely as a localized orofacial pain condition.