Relationships Among Non-Functional Occlusal Habits, Temporomandibular Disorder Symptoms, and Skeletal Morphology in...

Background/Objectives: Non-functional oral habits, such as unilateral chewing, bruxism, and clenching, may exacerbate temporomandibular disorder (TMD) symptoms and affect skeletal morphology in patients with dentofacial deformities. This study aimed to elucidate the relationships among these habits, TMD symptoms, and mandibular morphology, and to examine the association between non-functional habits and TMD symptom severity. Methods: A cross-sectional study was conducted in 141 patients with dentofacial deformities. At the initial consultation, participants completed a questionnaire assessing non-functional oral habits (unilateral chewing, bruxism, and clenching) and TMD symptoms, scored as follows: limited mouth opening (2 points), pain on opening (2 points), and joint sounds (1 point). Patients were stratified into three groups according to the number of habits (≥2, 1, none). Total TMD scores were compared among groups, and the relationship between unilateral chewing and mandibular asymmetry was analyzed. Results: Unilateral chewing was reported by 82 patients (58%), bruxism by 28 (20%), and clenching by 29 (21%). Mean TMD scores were 1.94 (range: 0-5) in patients with ≥2 habits, 1.50 (0-5) in those with one habit, and 0.86 (0-3) in those without habits. TMD symptoms were significantly more severe in patients with multiple habits (p < 0.05). Among patients with mandibular asymmetry, 41 of 56 (73%) reported unilateral chewing, which was significantly higher than in those without asymmetry (42 of 85; 49%) (p < 0.05). Conclusions: In patients with dentofacial deformities, multiple non-functional oral habits were associated with greater TMD symptom severity, and unilateral chewing was significantly associated with mandibular asymmetry.