Effect of Nail Biting Habit on Mandibular Bone Structure: A Retrospective Radiological Study

Nail biting (onychophagia) is a common parafunctional habit characterized by repetitive and non-functional biting behavior. Although the effects of nail biting on dental structures and occlusion have been reported, its potential effects on mandibular bone structure remain unclear. This retrospective radiological study aims to evaluate the association between nail biting habit and mandibular bone characteristics using fractal analysis and panoramic morphometric indices. Existing panoramic radiographs of individuals with and without nail biting habits will be retrospectively analyzed. Trabecular bone complexity, mandibular cortical width, panoramic mandibular index, and Klemetti index values will be compared between groups to investigate whether nail biting habit is associated with alterations in mandibular bone morphology.

Inclusion Criteria: * Children aged 8-10 years who were examined at the Department of Pediatric Dentistry, Faculty of Dentistry, Recep Tayyip Erdoğan University. * Systemically healthy participants. * Participants with available diagnostic-quality panoramic radiographs obtained during routine dental examinations. * Participants with and without a history of nail biting habit. * Panoramic radiographs with sufficient image quality for fractal dimension analysis and mandibular morphometric measurements. * Radiographs without periapical pathology in teeth adjacent to the regions of interest (ROI) used for fractal analysis. * Participants with at least 20 existing teeth. * Radiographic records with available parental radiographic information and consent documentation. Exclusion Criteria: * Participants with systemic diseases or conditions that may affect bone metabolism, including diabetes mellitus, osteoporosis, osteomalacia, renal diseases, hypothyroidism, or hyperparathyroidism. * Participants using medications that may influence bone density or bone metabolism. * Participants with temporomandibular joint disorders affecting the subcondylar region. * Participants with mandibular pathological conditions, including cysts, tumors, or other lesions affecting mandibular bone structure. * Participants with periapical pathology adjacent to the regions selected for fractal analysis. * Participants with fewer than 20 teeth. * Panoramic radiographs with insufficient diagnostic quality or image artifacts that prevent reliable measurements. * Radiographs that do not allow accurate evaluation of mandibular cortical and trabecular bone parameters.