DC/TMD Axis II Instruments and Their Association with MRI-Based Structural Classification of the Temporomandibular Joint and Oral Function in Female Patients with Malocclusion: A Cross-Sectional Study

Background/Objectives: Few studies have examined the associations of the Oral Behaviors Checklist (OBC) and the Jaw Functional Limitation Scale (JFLS) of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis II with magnetic resonance imaging (MRI)-based structural characterization of the temporomandibular joint, and most have analyzed these instruments only at the scale level. We examined these associations in female patients with malocclusion in a sample that was selected without symptom-based screening and independently selected under the eligibility criteria of the present study.

Methods

In this cross-sectional study, 240 female patients with malocclusion who had undergone TMJ MRI irrespective of symptoms were classified according to MRI findings into four groups: an osteoarthritis (OA) group characterized by degenerative osseous changes in the mandibular condyle, bilateral disc displacement (BDD), unilateral disc displacement (UDD), and Osseous Change/Disc Displacement negative (OC/DD (-)) groups (n = 39, 89, 53, and 59, respectively). Individual items, scale scores, and five oral function parameters were compared using the Kruskal-Wallis test followed by Dunn's post hoc test, as appropriate. The OBC total score and the JFLS score were the primary outcomes, whereas item-level and oral function analyses were exploratory. The JFLS was analyzed as a continuous variable; for the OBC, a total score ≥ 25 defined a high oral behavior score, and odds ratios (ORs) were estimated using logistic regression. A prespecified ordered trend was evaluated using the Jonckheere-Terpstra test.