Phenotypes of painful TMDs and bruxism based on clinical, psychosocial and somatosensory features: a cluster analysis

Abstract

To identify pain phenotypes among individuals with bruxism and painful temporomandibular disorders (TMD) by integrating clinical, psychosocial, and somatosensory variables. This cross-sectional observational study included 54 adults who self-reported and were clinically assessed with sleep and/or awake bruxism and painful TMD. Participants underwent a standardized clinical examination per the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), quantitative sensory testing including pressure pain thresholds and conditioned pain modulation, and completed validated questionnaires assessing pain characteristics, psychosocial factors, sleep quality, and symptoms associated with central sensitization. Agglomerative hierarchical cluster analysis using Gower distance and Ward’s method was performed on standardized variables. Two distinct pain phenotypes were identified. Cluster 1 ( n = 16) reflected a predominantly peripheral profile, characterized by localized pain, lower psychosocial burden, better sleep quality, higher pressure pain thresholds, and mild functional limitation. Cluster 2 ( n = 38) demonstrated a multisystem sensitized phenotype, marked by greater pain intensity and longer duration, a higher number of painful body areas, more mixed-type TMD pain, poorer sleep quality, heightened emotional distress, increased symptom burden related to central sensitization syndromes, lower pressure pain thresholds, and higher functional limitation. Clinically assessed bruxism behaviors did not differ between clusters and therefore did not contribute to phenotypic differentiation. Distinct pain phenotypes could be identified among bruxers with painful TMD, suggesting heterogeneity in the underlying pain mechanisms and symptom burden. Multidimensional phenotyping integrating clinical, psychosocial, and somatosensory domains may support mechanism-oriented clinical reasoning and provide a framework for future studies investigating individualized management strategies. Multidimensional pain phenotyping may assist clinicians in stratifying individuals with bruxism and painful TMD by identifying underlying pain mechanisms and predominant clinical and somatosensory characteristics, thereby guiding more individualized management strategies.