Objectives To investigate the prognosis and prognostic factors associated with pain intensity and function in individuals with temporomandibular disorders (TMDs). Secondary objectives included identifying prognostic factors related to symptom progression, subsequent treatment needs and psychosocial outcomes. Design Systematic review with meta-analysis. Data sources Medline, Dentistry and Oral Sciences Source, SportDiscus and CINAHL (EBSCOhost) were searched up to September 2025. Eligibility criteria Prospective longitudinal studies examining prognostic factors for pain intensity or functional outcomes in adults with TMD, with a minimum follow-up of 3 months. Data extraction and synthesis Two independent reviewers screened titles and abstracts and assessed full texts for eligibility. Data were extracted in duplicate using a standardised protocol that included study characteristics, prognostic factors and outcomes. Risk of bias was assessed using the QUIPS (Quality in Prognosis Studies) tool, and the certainty of evidence was graded using a modified GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. Meta-analyses were performed with random-effects models, reporting ORs and 95% CIs. Heterogeneity was evaluated using I² (I-squared) and Tau² (Tau-squared) statistics. Where pooling was not feasible, findings were synthesised narratively. Results Nine prospective studies met the inclusion criteria; eight were included in quantitative analyses (n=4282) and one large cohort was synthesised narratively (n=94 769), for a total of 99 051 participants. After standardising definitions, 56 candidate factors were analysed. In adjusted models for pain, pain provoked by movement or palpation was associated with a worse course (eg, joint pain with sound: OR=2.10, 95% CI 1.39 to 3.18; muscle pain during movement: OR=2.10, 95% CI 1.33 to 3.31), while shorter pain duration (OR=0.25, 95% CI 0.09 to 0.70) and greater pain-free mouth opening (OR=0.60, 95% CI 0.40 to 0.90) were protective. For the function outcome, pain intensity was associated with poorer outcomes (OR=1.39, 95% CI 1.14 to 1.69), whereas age, sex, depression, somatisation, disability days and self-efficacy showed no consistent associations. Conclusions In adults with TMD, pain provoked by movement or palpation and higher pain intensity were consistently associated with less favourable prognoses. Conversely, shorter pain duration and greater pain-free opening were associated with better outcomes. These associations are non-causal and based on low to very low certainty evidence amid methodological heterogeneity. While they may inform risk stratification, they should not guide treatment decisions without confirmatory longitudinal studies using standardised outcomes and improved control of confounders. PROSPERO registration number CRD42024557159.
Amaral et al. (Sun,) studied this question.