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

Although cross-sectional studies of temporomandibular disorders (TMDs) 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 multivariate 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

Potential Psychosocial Risk Factors for Chronic TMD: Descriptive Data and Empirically Identified Domains from the OPPERA Case-Control Study

Case-control studies have consistently associated psychosocial factors with chronic pain in general, and with temporomandibular disorders (TMD) specifically. Moreover, a handful of prospective studies suggest that pre-existing psychosocial characteristics represent risk factors for new onset TMD. The current study presents psychosocial findings from the baseline case-control study of the Orofacial Pain Prospective Evaluation and Risk Assessment (OPPERA) cooperative agreement. For this study, 1,633 TMD-free controls and 185 TMD cases completed a battery of psychosocial instruments assessing general psychosocial adjustment and personality, affective distress, psychosocial stress, somatic awareness, and pain coping and catastrophizing. In bivariate and demographically-adjusted analyses, odds of TMD were associated with higher levels of psychosocial symptoms, affective distress, somatic awareness, and pain catastrophizing. Among controls, significant gender and ethnic group differences in psychosocial measures were observed, consistent with previous findings. Principal component analysis was undertaken to identify latent constructs revealing four components: stress and negative affectivity, global psychosocial symptoms, passive pain coping, and active pain coping. These findings provide further evidence of associations between psychosocial factors and TMD. Future prospective analyses in the OPPERA cohort will determine if the premorbid presence of these psychosocial factors predicts increased risk for developing new-onset TMD

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

Temporomandibular disorders (TMD) overlap 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 18–44 years had no history of TMD and were clinically free of TMD when enrolled in 2006–08 at four U.S. study sites in the 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 lower back pain (adjusted hazard ratio [AHR] = 1.50, 95% confidence limits [95% CL]: 1.08, 2.10) and 75% higher for people with genital pain symptoms (AHR = 1.75 [95% CL: 1.04, 2.93]) than people without a history of these pain disorders. Digit ratio, a marker of intra-uterine 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

Pain Sensitivity Risk Factors for Chronic TMD: Descriptive Data and Empirically Identified Domains from the OPPERA Case Control Study

Many studies report that people with temporomandibular disorders (TMD) are more sensitive to experimental pain stimuli than TMD-free controls. Such differences in sensitivity are observed in remote body sites as well as in the orofacial region, suggesting a generalized upregulation of nociceptive processing in TMD cases. This large case-control study of 185 adults with TMD and 1,633 TMD-free controls measured sensitivity to painful pressure, mechanical cutaneous, and heat stimuli, using multiple testing protocols. Based on an unprecedented 36 experimental pain measures, 28 showed statistically significantly greater pain sensitivity in TMD cases than controls. The largest effects were seen for pressure pain thresholds at multiple body sites and cutaneous mechanical pain threshold. The other mechanical cutaneous pain measures and many of the heat pain measures showed significant differences, but with lesser effect sizes. Principal component analysis (PCA) of the pain measures derived from 1,633 controls identified five components labeled: (1) heat pain ratings, (2) heat pain aftersensations and tolerance, (3) mechanical cutaneous pain sensitivity, (4) pressure pain thresholds, and (5) heat pain temporal summation. These results demonstrate that, compared to TMD-free controls, chronic TMD cases are more sensitive to many experimental noxious stimuli at extra-cranial body sites, and provides for the first time the ability to directly compare the case-control effect sizes of a wide range of pain sensitivity measures

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

Incidence of temporomandibular disorders (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 non-specific orofacial symptoms. Other important baseline risk factors were pre-existing 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

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 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 people 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

Potential Autonomic Risk Factors for Chronic TMD: Descriptive Data and Empirically Identified Domains from the OPPERA Case-Control Study

Several case-control studies have been conducted that examine the association between autonomic variables and persistent pain conditions; however, there is a surprising dearth of published studies in this area that have focused on temporomandibular disorders (TMD). The current study presents autonomic findings from the baseline case-control study of the OPPERA (Orofacial Pain: Prospective Evaluation and Risk Assessment) cooperative agreement. Measures of arterial blood pressure, heart rate, heart rate variability, and indirect measures of baroreflex sensitivity were assessed at rest and in response to a physical (orthostatic) and psychological (Stroop) stressors in 1633 TMD-free controls and 185 TMD cases. In bivariate and demographically adjusted analyses, greater odds of TMD case status were associated with elevated heart rates, reduced heart rate variability, and reduced surrogate measures of baroreflex sensitivity across all experimental procedures. Principal component analysis was undertaken to identify latent constructs revealing five components. These findings provide evidence of associations between autonomic factors and TMD. Future prospective analyses in the OPPERA cohort will determine if the presence of these autonomic factors predicts increased risk for developing new onset TMD

Psychological Factors Associated With Development of TMD: The OPPERA Prospective Cohort Study

Case-control studies have consistently associated psychological factors with chronic pain in general and with temporomandibular disorders (TMD) specifically. However, only a handful of prospective studies has explored whether pre-existing psychological characteristics represent risk factors for first-onset TMD. The current findings derive from the prospective cohort study of the Orofacial Pain Prospective Evaluation and Risk Assessment (OPPERA) cooperative agreement. For this study, 3,263 TMD-free participants completed a battery of psychological instruments assessing general psychological adjustment and personality, affective distress, psychosocial stress, somatic symptoms, and pain coping and catastrophizing. Study participants were then followed prospectively for an average of 2.8 years to ascertain cases of first-onset of TMD, and 2,737 provided follow-up data and were considered in the analyses of TMD onset. In bivariate and demographically-adjusted analyses, several psychological variables predicted increased risk of first-onset TMD, including reported somatic symptoms, psychosocial stress, and affective distress. Principal component analysis of 26 psychological scores was used to identify latent constructs, revealing four components: stress and negative affectivity, global psychological and somatic symptoms, passive pain coping, and active pain coping. In multivariable analyses, global psychological and somatic symptoms emerged as the most robust risk factor for incident TMD. These findings provide evidence that measures of psychological functioning can predict first-onset of TMD. Future analyses in the OPPERA cohort will determine whether these psychological factors interact with other variables to increase risk for TMD onset and persistence