Psychosomatic function and dentofacial morphology in patients with malocclusion: a multicentre cross-sectional collaborative study identifying independent factors associated with gastro-oesophageal reflux disease

Purpose Malocclusion affects oral function and systemic health; however, its integrated mechanisms remain unclear. Further, previous studies have focused on anteroposterior discrepancies, and the systemic significance of lateral dentofacial abnormalities is unclear. Thus, we aimed to evaluate the relationships between dentofacial morphology and psychosomatic function in patients with malocclusion and identify factors associated with gastro-oesophageal reflux disease (GERD).Materials and methods This multicentre cross-sectional study was conducted across five Japanese universities in accordance with the Declaration of Helsinki and STROBE guidelines. Consecutive patients aged 11–65 years scheduled to initiate comprehensive orthodontic treatment with multibracket appliances between January 2023 and May 2025 were enrolled (n = 287). Psychological status, physical and oral function, general and oral health–related quality of life (QOL), and dentofacial morphology using lateral and posteroanterior cephalograms were compared between patients with and without GERD, defined as FSSG-positive GERD (FSSG score ≥ 8). Intergroup comparisons and multivariable logistic regression analyses were performed with adjustments for age and sex.Results The prevalence of FSSG-positive GERD was 33.5%. The GERD group was significantly older with greater mandibular lateral deviation, higher anxiety and daytime sleepiness, and poorer oral health–related QoL. Multivariate analysis identified mandibular lateral deviation (odds ratio [OR] 2.69, 95% confidence interval [CI] 1.36–5.35) and oral health–related QoL (OR 2.08, 95% CI 1.19–3.64) as independent factors associated with GERD.Conclusion Mandibular lateral deviation and impaired oral health–related QoL were independently associated with GERD, suggesting a close relationship between lateral dentofacial abnormalities and systemic function.