Evaluation of mandibular bone quality and coronoid process length in bruxism patients with cone beam computed tomography

Objective: Bruxism is a repetitive jaw muscle activity characterized by clenching or grinding of the teeth and/or clenching or thrusting of the jaw. Forces exceeding physiological limits cause structural changes in the teeth, masticatory muscles, mandible, and temporomandibular joint. This study aims to detect potential changes in mandibular bone density associated with increased masticatory muscle activity in bruxism, particularly in regions of muscle attachment and areas under direct mechanical stress, and to assess possible alterations in the coronoid process related to temporalis muscle hyperactivity. Method: Between August 2024 and February 2025, 50 healthy individuals who presented to the Faculty of Dentistry at Akdeniz University with complaints of teeth grinding and were diagnosed with bruxism based on clinical evaluation were included in the study, along with 50 healthy individuals who underwent CBCT imaging for various reasons (impacted teeth, implants, cysts, etc.). Density analysis and anatomical measurements were performed on the CBCT images of all cases, and the groups were compared using an Independent Samples T-Test. Results: Density analysis demonstrated significantly higher bone density in the bruxism group at the apical region of the mandibular first molar, the medial pterygoid and the masseter attachment site at the mandibular angle, the coronoid process, and the articular eminence, whereas no significant difference was observed in the condyle. Morphometric evaluation revealed significant increases in condylar length, coronoid process length, the coronoid/condyle ratio, and the anteroposterior width of the coronoid process in bruxism patients. Moreover, the vertical distance between the superior margin of the zygomatic arch and the apex of the coronoid process was shorter in the bruxism group compared with controls. In contrast, no significant intergroup differences were found for ramus length, the horizontal distance between the coronoid process and the inner surface of the zygomatic arch, or the mediolateral width of the coronoid process. Conclusion: Bruxism is not merely a functional problem, but a habit that can cause significant and serious morphological changes in the mandibular bone structures. Therefore, early diagnosis of bruxism and the application of appropriate treatment approaches are critical in preventing progressive bone changes. Key words: bruxism, coronoid, condyle