Associations Between Anteroposterior Occlusal Class, Musculoskeletal Pain Patterns, and Temporomandibular Disorders in Young Adults: A Cross-Sectional Study

<b>Background:</b> The relationship between sagittal malocclusion, temporomandibular disorders (TMD), and musculoskeletal pain remains uncertain. <b>Methods:</b> Cross-sectional study (April 2020-August 2021) in Małopolska, Poland. Ninety participants (ages 19-35) were classified into Angle Classes I-III (n = 30 each) and examined using RDC/TMD (Axis I/II). A proprietary, nonvalidated, piloted whole-body pain-map questionnaire, presented in anterior and posterior views and subdividing the body into predefined craniofacial, spinal, and limb regions, was used to capture pain presence, Numerical Rating Scale (NRS, 0-10) scores by region, and the total number of painful sites. Group differences were analyzed using χ² and Kruskal-Wallis tests with corresponding effect sizes (measures of association strength). For NRS outcomes, a minimal clinically important difference (MCID)-defined as the smallest difference in NRS considered clinically relevant-was prespecified as approximately 1 point. <b>Results:</b> Occlusal class was not associated with TMD Axis I prevalence. However, sagittal malocclusion-particularly Class III-was linked to a less favorable pain profile. Left temporal pain was more frequent in Class III than in Classes I-II (<i>p</i> = 0.024, Cramér's V = 0.31, medium effect), and cervical spine pain occurred more often in malocclusion groups than in Class I (<i>p</i> = 0.043, Cramér's V = 0.26, small effect), indicating statistically significant associations. Cervical pain intensity was higher in Classes II-III than in Class I, with a pooled mean difference-defined as the difference in mean NRS between the combined Classes II-III and Class I-of 1.23 NRS points (95% CI 0.38-2.08), exceeding the ≈1-point MCID and suggesting a clinically important burden. The total number of painful sites was also greater in Class III than in Class I (<i>p</i> = 0.023, η² = 0.09; Δ = 1.40 sites, 95% CI 0.39-2.41), which indicates a statistically significant association with a medium effect size and a higher overall pain burden. <b>Conclusions</b>: Sagittal occlusal class was not associated with TMD diagnosis, but malocclusion-especially Class III-was associated with a more unfavorable craniofacial pain pattern and higher cervical pain burden (<i>p</i> ≤ 0.05), with effects of potential clinical relevance.