The associations of the diagnostic criterion pain modified by function with functional limitation and behavioral frequency

The aim is to assess the associations of jaw functional limitation and jaw overuse behavior with pain modified by function as a required diagnostic criterion for painful temporomandibular disorders. This cross-sectional study from the TMJ Impact Project utilized secondary data analyses of 249 participants who met the inclusion criteria of having facial pain in the prior 30 days and valid responses to the pain modified by function (Items 4A–D derived from the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Symptom Questionnaire). Independent t-tests (alpha = 0.05) were used to assess the associations between pain modified by function items with similarly assessed concepts from the Jaw Functional Limitation Scale (JFLS) and Oral Behavior Checklist (OBC). The magnitude of each association was converted to an effect size for interpretation. Pain modified by mastication (item A) and jaw mobility (item B) were significantly associated with the corresponding JFLS items (effect sizes <0.1–1.0) and exhibited a hierarchical pattern. Pain modified by jaw overuse behaviors (item C) was associated with the corresponding OBC items (effect sizes <0.1–0.8). Pain modified by other functions (item D) exhibited associations with the corresponding JFLS items (effect sizes 0.5–0.9). Pain modified by function is an integral part of musculoskeletal disorders and anchored to the interoceptive body experience. Results indicate that the DC/TMD pain modified by function questions used as diagnostic criteria have sufficient scope and the responses fit with data measuring related constructs pertaining to etiology (OBC) or consequences (JFLS).