Does Nail Biting Damage Your Teeth? What Has Actually Been Measured
Health · 3 min read · Published 2026-10-08
By Igor Gazivoda · Founder, Stop Biting
Less is measured than articles claim: one study on root resorption, one disputed on malocclusion, one on jaw signs. What is established and what is not.
Does nail biting damage your teeth?
Possibly, but the evidence is thinner than most articles about nail biting imply. A main clinical review lists gingival injury, increased incisor wear, malocclusion, apical root resorption and rotation of the incisors as dental complications (Lee & Lipner, 2022), but that is a list the review asserts, and only one item on it traces to a measurement we could find. Below is what has been measured, what is disputed, and what is repeated without support.
What has been measured?
Root resorption, in orthodontic patients. In a Swedish study, 21 severe nail biters undergoing fixed orthodontic treatment had a significantly higher apical root resorption index than 21 matched patients without the habit, and the difference was already present before treatment started (Odenrick & Brattström, 1985). Everyone compared was an orthodontic patient, and the direction of the association is not established.
Jaw signs and symptoms. In 240 adolescents, nail biting was significantly associated with self-reported signs and symptoms of temporomandibular disorder (p = 0.001), alongside lip and object biting and tooth grinding, which the study does not separate (Motghare et al., 2015). It was cross-sectional, used a screening questionnaire and reported no effect size.
What is disputed?
Malocclusion, meaning a bite that does not meet properly. The most recent primary study we found to test it directly assessed 503 Japanese preschoolers by examination, took habits from a parental questionnaire, and found nail biting significantly and negatively related to malocclusion. Its authors concluded it "may not necessarily be a deleterious habit for the occlusion" (Otsugu et al., 2023). We are not claiming nail biting protects teeth; it is one cross-sectional study of primary dentition. But anyone stating flatly that nail biting causes malocclusion is contradicted by the only recent study that measured it.
What is repeated without support?
Incisor wear, chipped teeth and gum disease are widely repeated. We could not find a study that measured incisor wear in nail biters, and the review's own references for the dental items are another review and a quality-of-life study with no dental data. The general claim that nail biting causes gum disease traces, as far as we can follow it, to a single case report in which a bitten-off nail fragment lodged under the gum and produced a local periodontal infection; the tooth alongside was already non-vital, and the authors call such impactions "relatively rare" (Ellison et al., 2014). A case report shows something can happen, not how often.
What should I do about it?
If you have braces, jaw pain, clicking, or a tooth that has changed, tell a dentist; they can examine what a general article cannot. Whether or not biting is harming your teeth, a habit that runs hundreds of times a day is worth interrupting, and the first step is noticing it.
Related reading: nail biting with braces, jaw pain and TMJ, nail biting and teeth grinding, and the wider health risks. For the method, see how to stop nail biting.
Sources:
- Lee DK, Lipner SR. Update on Diagnosis and Management of Onychophagia and Onychotillomania. Int J Environ Res Public Health. 2022;19(6):3392.
- Odenrick L, Brattström V. Nailbiting: frequency and association with root resorption during orthodontic treatment. Br J Orthod. 1985;12(2):78–81.
- Otsugu M, Sasaki Y, Mikasa Y, et al. Incompetent lip seal and nail biting as risk factors for malocclusion in Japanese preschool children aged 3–6 years. BMC Pediatr. 2023;23(1):532.
- Motghare V, Kumar J, Kamate S, et al. Association Between Harmful Oral Habits and Sign and Symptoms of Temporomandibular Joint Disorders Among Adolescents. J Clin Diagn Res. 2015;9(8):ZC45–48.
- Ellison R, Rahman S, Barker D, Larmour C. Onychophagia and subgingival foreign body embedment: a case report. Br Dent J. 2014;216(9):519–520.
A note on medical advice
This article is for general information only and is not medical advice. Nail biting and related body-focused repetitive behaviours (BFRBs) can have medical and psychological dimensions that deserve individual attention. For diagnosis or treatment — of BFRBs, infections, or any condition discussed here — consult a qualified professional: a GP or dermatologist for physical symptoms, or a therapist experienced with BFRBs for the habit itself. The TLC Foundation for Body-Focused Repetitive Behaviors (bfrb.org) maintains a directory of BFRB-informed clinicians.