In a systematic review and meta-analysis, investigators synthesized current evidence on prognostic factors associated with pain and functional outcomes in patients with temporomandibular disorders, highlighting the importance of pain-related clinical signs while underscoring the low certainty of available data.
The investigators analyzed nine prospective longitudinal studies comprising 99,051 participants to identify the potential factors influencing the course of temporomandibular disorders (TMD). Among these, eight studies were included in quantitative meta-analyses, while one large cohort was assessed narratively. In total, 56 candidate prognostic factors were evaluated.
The findings indicated that pain triggered by movement or palpation was consistently associated with poorer outcomes. Specifically, joint pain accompanied by sound and muscle pain during movement were among the strongest predictors of a poorer prognosis, each associated with more than double the risk of persistent or worsening pain.
Conversely, shorter pain duration and greater pain-free mouth opening were identified as protective factors. The patients with shorter symptom duration had significantly better outcomes, while those with greater pain-free opening was also associated with improved prognosis.
For functional outcomes, higher baseline pain intensity emerged as a key predictor of poorer function over time. In contrast, commonly considered demographic and psychosocial factors—including age, sex, depression, somatization, and self-efficacy—showed no consistent association with either pain or function.
Despite these findings, the investigators emphasized that the basis of evidence remains limited.
“These associations are noncausal and based on low to very low-certainty evidence amid methodological heterogeneity,” wrote lead study author Maitê Amaral, of the Master and Doctoral Program of Health Science at the Faculdade de Ciências Médicas da Santa Casa de São Paulo in Brazil, and colleagues, noting that variability in the study design, outcome measures, and risk of bias restricted the strength of the conclusions.
The investigators also highlighted a notable gap in the literature: the lack of studies examining the natural course of TMD without focusing on predictive variables. Most of the included studies aimed to identify prognostic factors rather than describe patterns of recovery or progression.
Clinically, the results suggested that observable pain responses during examination may be more informative for prognosis compared with demographic or psychosocial characteristics. However, the investigators cautioned against overinterpretation.
“While they may inform risk stratification, they should not guide treatment decisions without confirmatory longitudinal studies using standardized outcomes and improved control of confounders,” they concluded.
The investigators called for more rigorous, large-scale longitudinal research with standardized methodologies to better define prognostic pathways in TMD. Until then, clinicians were advised to use the findings as part of a broader, individualized assessment rather than as definitive predictors of patient outcomes.
The study authors reported no competing interests.
Source: BMJ Open
