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

July 31, 2026 updated by: DİLARA NİL GÜNAÇAR, Recep Tayyip Erdogan University Training and Research Hospital

Evaluation of the Effects of Nail Biting Habit on Mandibular Bone Structure Using Fractal Analysis and Panoramic Morphometric Indices: 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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

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.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
100

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

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Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

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.

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Nail Biting Habit Group
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.
Control Group Without Nail Biting Habit
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.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Mandibular Trabecular Bone Structure Assessed by Fractal Dimension Analysis
Time Frame: Baseline
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.
Baseline

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Panoramic Mandibular Index (PMI)
Time Frame: Baseline
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.
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Recep Tayyip Erdogan University Training and Research Hospital

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
July 27, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 5, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 7, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 28, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 31, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 3, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 3, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 31, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2026/315

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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