Background: Temporomandibular disorder (TMD) pain is common among adolescents. The association between painful TMD and other comorbidities has been demonstrated. However, the difference between short-term (<6 months) and long-term (≥ 6 months) painful TMD is not yet clear. Objective:The aim of this study was to assess the association between comorbidities and short-and long-term painful TMD among adolescents. Methods:In this cross-sectional study, adolescents were recruited from Montreal (Canada), Nice (France) and Arceburgo (Brazil). Self-reported painful TMD, comorbidities, school absence and analgesic intake were assessed using reliable instruments.Multivariable logistic regression analyses were conducted to assess the study aims. Results:The prevalence of short-and long-term painful TMD was estimated at 22.29% and 9.93% respectively. The number of comorbidities was associated with short-(OR = 1.71, 95%CI = 1.53-1.90) and long-term painful TMD (OR = 1.79, 95%CI = 1.55-2.08) compared to controls. Frequent headaches (OR short-term = 4.39, 95%CI = 3.23-5.98, OR long-term = 3.69, 95%CI = 2.45-5.57) and back pain (OR short-term = 1.46, 95%CI = 1.06-2.03, OR long-term = 1.69, 95%CI = 1.11-2.59) were associated with both painful TMD groups. Frequent neck pain (OR = 2.23, 95%CI = 1.53-3.26) and allergies were only associated with short-term painful TMD (OR = 1.54, 95%CI = 1.13-2.10). Frequent stomach pain was related to long-term (OR = 2.01, 95%CI = 1.35-3.26), and it was the only comorbidity significantly more frequent among the long than short-term TMD (OR = 1.82, 95%CI: 1.14-2.90). These analyses were adjusted by sex, age and city. Conclusion:In this multi-centre study, both short-and long-term painful TMD are associated with frequent headaches and back pain, whereas frequent neck pain and allergies are related to only short-term and frequent stomach pain with long-term painful TMD.

Background Temporomandibular disorders (TMDs) are common and cause persistent pain. Comorbidities are associated with TMDs and can affect the effectiveness of their treatments. The literature is lacking enough evidence on the difference between acute and chronic pain, particularly in TMDs. Investigating this difference could highlight potential risk factors for the transition from acute to chronic pain–related TMDs. Aim To compare the likelihood of back and neck pain (BP, NP) between acute and chronic pain–related TMDs (AP-TMD, CP-TMD) as defined by pain duration and pain-related disability.‎ Methods Participants with AP-TMDs (≤3 months) and CP-TMDs (>3 months) were recruited according to the diagnostic criteria and research diagnostic criteria of TMD. BP and NP were assessed using a self-reported checklist. CP-TMDs defined by disability (chronic disability) and depression and anxiety symptoms were assessed using validated instruments. Logistic regression analyses were employed. Results This study enrolled 487 adults with AP-TMD ( n = 118) and CP-TMD ( n = 369). Relative to AP-TMD, participants with CP-TMD had twice the odds of reporting NP (odds ratio [OR] = 2.17‎, 95% CI 1.27–3.71) but not BP ‎‎(OR = 0.96, 95% CI 0.57–1.64). Participants with chronic disability were twice as likely to report NP ‎(OR = 1.95‎, 95% CI 1.20–3.17‎) but not BP (OR = 1.13, 95% CI 0.69–1.82)‎ compared to those without. All analyses were adjusted for age, sex, and anxiety and depression symptoms. Conclusions Within the limitations of this study, results suggest that central dysregulation or trigeminocervical convergence mechanisms are implicated in the process of pain-related TMD chronification and highlight the relevance of considering disability when defining CP-TMDs.

Although most cases of pain-related temporomandibular disorders (TMD) are mild and self-limiting, about 10% of TMD patients develop severe disorders associated with chronic pain and disability. It has been suggested that pain intensity contributes to the transition from acute to chronic pain-related TMD. Therefore, the aims of this current prospective cohort study were to assess if pain intensity, pain always being present, pain or stiffness on awakening, jaw activities, and interference, were associated with the transition from acute to chronic pain-related TMD at 3 months of follow-up. One hundred and nine participants, recruited from four clinics in Montreal and Ottawa, received examinations and completed the required instruments at baseline and at the 3rd month of follow-up. In a multivariable analysis including sex, age, characteristic pain index (CPI) (OR = 1.03, 95%CI = 1.01–1.06, P = 0.005), moderate to severe average pain intensity (OR = 3.51, 95%CI = 1.24–9.93, P = 0.02), disability points score (OR = 1.29, 95%CI = 1.06–1.57, P = 0.01), interferences (ORs = 1.30–1.32, P = 0.003–0.005), screening score (OR = 1.37, 95%CI = 1.08–1.76, P = 0.01), and pain always present (OR = 2.55, 95%CI = 1.08–6.00, P = 0.03) assessed at first-visit were related to the transition outcome at the 3rd month of follow-up. Further, we found that if 4 patients with acute pain-related TMD on average were exposed to these risk factors at baseline, 1 would have the transition from acute to chronic pain at 3 months of follow-up. Results indicate that these factors are associated with the transition from acute to chronic pain-related TMD, and therefore should be considered as important factors when evaluating and developing treatment plans for patients with pain-related TMD.