An observational study in Onychophagia, sponsored by Recep Tayyip Erdogan University Training and Research Hospital. Not yet recruiting. Open to participants aged 8 Years to 10 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-03.
Sponsored by Recep Tayyip Erdogan University Training and Research Hospital · Observational
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.
Nail biting (onychophagia) is classified as a body-focused repetitive behavior and represents a common parafunctional habit, particularly among children and adolescents. Continuous repetitive mechanical forces generated during nail biting may affect the stomatognathic system; however, the possible effects of this habit on mandibular bone structure have not been sufficiently investigated.
Fractal analysis is a radiological assessment method used to evaluate trabecular bone architecture by quantifying structural complexity. Higher fractal dimension values indicate increased complexity of bone patterns. In addition, panoramic morphometric indices such as mandibular cortical width, panoramic mandibular index, and Klemetti index provide information regarding cortical bone quality and quantity.
In this retrospective case-control study, existing panoramic radiographs of individuals with and without nail biting habits will be evaluated. Radiological parameters including fractal dimension, mandibular cortical width, panoramic mandibular index, and Klemetti index will be compared between groups. This study aims to determine whether nail biting habit is associated with measurable changes in mandibular trabecular and cortical bone characteristics.
Recep Tayyip Erdogan University Training and Research Hospital is the lead sponsor of 88 studies on the registry; 19 are open to participants now.
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The study population will consist of systemically healthy children aged 8-10 years who previously underwent routine dental examination at the Department of Pediatric Dentistry, Faculty of Dentistry, Recep Tayyip Erdoğan University. Existing panoramic radiographs obtained during routine clinical care will be retrospectively analyzed. Participants will be categorized into two groups according to the presence or absence of nail biting habit. A minimum of 100 participants will be included, with equal distribution between the nail biting habit group and the control group and balanced sex distribution. Mandibular bone characteristics will be evaluated using fractal dimension analysis and panoramic radiographic morphometric indices, including mandibular cortical width, panoramic mandibular index, mandibular cortical index (Klemetti index), and other mandibular bone measurements. No intervention will be performed; only existing radiographic records will be assessed.
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Exclusion Criteria:
This cohort includes systemically healthy children aged 8-10 years with a documented nail biting habit. Existing panoramic radiographs obtained during routine dental examinations will be retrospectively analyzed. Mandibular trabecular bone structure will be evaluated using fractal dimension analysis, and cortical bone characteristics will be assessed using mandibular cortical width, panoramic mandibular index, and Klemetti index measurements. No intervention will be performed.
This cohort includes systemically healthy children aged 8-10 years without a history of nail biting habit. Existing panoramic radiographs obtained during routine dental examinations will be retrospectively analyzed using the same radiological evaluation methods. Mandibular trabecular and cortical bone characteristics will be compared with those of the nail biting habit group. No intervention will be performed.
Mandibular Trabecular Bone Structure Assessed by Fractal Dimension Analysis
Mandibular trabecular bone architecture will be evaluated using fractal dimension analysis on panoramic radiographs. Fractal dimension measurements will be performed using the box-counting method described by White and Rudolph. Four regions of interest (ROIs) in the mandible will be analyzed, including the condylar subcortical region, supracortical region above the mandibular angle, area above the mandibular canal distal to the mental foramen, and anterior region of the mental foramen. Measurements will be performed bilaterally, and the mean fractal dimension value will be calculated for each participant. Higher fractal dimension values indicate greater trabecular bone complexity. The fractal dimension values will be compared between individuals with and without nail biting habit.
Time frame: Baseline
Panoramic Mandibular Index (PMI)
The panoramic mandibular index (PMI) will be calculated on panoramic radiographs as the ratio of mandibular cortical width to the distance between the inferior border of the mandible and the inferior margin of the mental foramen. Measurements will be performed bilaterally, and the mean value will be used for analysis.
Time frame: Baseline
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Nail Biting
Recep Tayyip Erdogan University Training and Research Hospital