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

## TL;DR

This study examines how pain related to jaw function is linked to jaw limitations and behaviors in people with facial pain.

## Contribution

The study provides empirical evidence on the validity of using pain modified by function as a diagnostic criterion for temporomandibular disorders.

## Key findings

- Pain modified by mastication and jaw mobility showed significant associations with jaw functional limitation items.
- Pain modified by jaw overuse behaviors was linked to oral behavior checklist items.
- Pain modified by other functions correlated with jaw functional limitation items.

## Abstract

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).