The Knowledge–Behavior Gap in Orthodontic Oral Hygiene: A Mixed-Methods Study with Development of a Patient-Centered Guidance Form

Background: Maintaining optimal oral hygiene during fixed orthodontic treatment is critical yet challenging. This study assessed oral hygiene knowledge, practices, and challenges among fixed orthodontic patients and developed a patient-centered guidance form. Methods: A sequential explanatory mixed-methods design was employed. A cross-sectional survey was conducted among 300 fixed orthodontic patients (150 males, 150 females) age range 13–31+ years followed by in-depth interviews with 15 purposively selected patients. Quantitative data were analyzed using non-parametric tests and multiple regression; qualitative data were analyzed thematically. Results: Scale reliability was acceptable to excellent (α = 0.681–0.941). Females demonstrated higher knowledge (p < 0.001); males showed better recall (p = 0.005). Knowledge increased with age and education (p < 0.001). A substantial knowledge–behavior gap was evident: 85% recognized interdental brushes as essential, but only 23% used them daily. Discomfort was the main barrier (77%), and 71% preferred mobile app reminders. Knowledge of auxiliary aids predicted recall (β = 1.912, p < 0.001), explaining 81.9% of variance. Notably, 100% reported current instructions are physically difficult to execute; 86% prioritized technique guidance. Conclusions: Fixed orthodontic patients demonstrate adequate knowledge but poor translation into practice. The patient-centered guidance form provides a practical resource to support oral hygiene self-management.