Introduction
Children often develop habits such as nail biting or lip biting without even realising they are doing it. These behaviours may occur when a child is bored, stressed, anxious, tired, or simply seeking comfort.
Occasional nail or lip biting is usually not a cause for concern. However, when a habit becomes frequent, forceful, or continues for a long time, it may begin to affect the teeth, gums, lips, or bite.
In this guide, we’ll explore why children may develop these habits, how persistent nail or lip biting can affect oral health, practical ways to help your child break the habit, and when it may be time to see a pediatric dentist.
What are Harmful Oral Habits?
Harmful oral habits are repeated behaviours involving the mouth, teeth, or jaw that may affect oral health or dental development when they occur frequently, with significant force, or over a prolonged period. They are also sometimes referred to as deleterious oral habits.
Common oral habits in children include:
- Nail biting
- Lip biting or lip sucking
- Thumb or finger sucking
- Tongue thrusting
- Mouth breathing
These habits are not necessarily harmful when they occur occasionally. The potential for dental or oral changes depends on factors such as how often the habit occurs, how long it continues, and the amount of force involved.
Key Takeway: A habit is more likely to cause problems when it is frequent, forceful, and long-lasting—not simply because the habit occurs.
Nail Biting in Children
Nail biting, medically known as Onychophagia, is a common repetitive habit in children that may continue into the teenage years and beyond.
How common is it?
Nail biting is a common childhood habit, although reported prevalence varies between studies and age groups. It is seen across different stages of childhood and may persist in some individuals.
Why children bite their nails
Common reasons may include:
- Stress or tension: Nail biting may act as a self-soothing behaviour during stressful situations.
- Boredom: Some children bite their nails when they are idle or have little to do.
- Habit or automatic behaviour: The child may bite their nails without consciously noticing it, particularly during activities such as watching television, reading, or doing homework.
- Emotional triggers: Changes in routine, frustration, tiredness, or other situations that increase tension may make the habit more noticeable.
The habit does not necessarily indicate that a child is anxious or experiencing an emotional problem. For many children, nail biting is simply a repetitive behaviour that becomes established over time.
Lip Biting and Lip Sucking Habits
Lip biting involves repeatedly biting or trapping the lip between the teeth, while lip sucking involves drawing the lip between the upper and lower front teeth. Lip sucking is considered a non-nutritive oral habit, similar to other sucking habits. Both the habits can become repetitive, unconscious habits, particularly in young children.
When these behaviours are frequent or prolonged, they may contribute to changes in tooth position or bite in some children.
Why it happens
- Comfort or self-soothing: Some children develop lip biting or sucking as a way of seeking comfort or relieving tension.
- Habit: The behaviour may become automatic and occur without the child realising it.
- An existing bite or tooth-positioning issue: In some children, a lip habit may develop alongside an existing bite or tooth-positioning issue.
- Stress or tiredness: The habit may become more noticeable during periods of stress, boredom, or fatigue.
Signs to watch for
Parents may notice:
- Redness, dryness, or chapping around the lips
- Repeated irritation or soreness of the lip
- A visible line or bite mark where the lip is repeatedly trapped between the teeth
- Swelling or thickening of the affected area
- The child repeatedly placing the lower lip between the upper and lower front teeth
Effects of Harmful Oral Habits on Teeth
While nail biting and lip biting affect the mouth in different ways, both may influence the teeth, gums, or bite when the habit is frequent, forceful, or prolonged.
Effects of nail biting
- Tooth wear or minor tooth damagefrom repeated biting forces
- Gradual wearing of tooth enamel
- Gum irritation or minor cuts from sharp nail edges
- May introduce bacteria from under the nails into the mouth
- May damage braces, brackets, or wires in children undergoing orthodontic treatment
Effects of lip biting and lip sucking:
- Increased pressure on the upper front teeth, which may influence their position
- Pressure on the lower front teeth, which may influence their position
- May contribute to changes in the bite, such as an open bite or increased overjet, in some children
- Lip irritation, including redness, dryness, soreness, or chapping
Important note: The potential effects of an oral habit depend on factors such as how often it occurs, how long it continues, the amount of force involved, and the child's stage of dental development. Persistent habits that begin to affect the teeth or bite may benefit from evaluation by a pediatric dentist.
Prevention & Habit-Breaking Tips
With patience and the right approach, parents can in many cases help children break these habits, especially when they start early and use consistent strategies without making the child feel criticised or ashamed.
Everyday strategies
- Identify the trigger: Notice when the habit happens most—boredom, stress, tiredness, or screen time.
- Keep hands and mouth occupied: Offer a stress ball, fidget toy, or activity during trigger moments.
- Maintain short, neat nails: Trimmed nails may make nail biting less appealing.
- Address underlying stress: If stress appears to trigger the habit, gentle conversation or reassurance may help more than repeated correction.
- Praise progress: Positive reinforcement is generally more helpful than scolding or negative attention.
If the habit persists
- Child-safe bitter-tasting nail polish: May help discourage some children from biting their nails.
- Lip balm: Can soothe and protect irritated lips, particularly when dryness or chapping encourages further biting.
- Habit-breaking appliances: In persistent cases, a pediatric dentist or orthodontist may recommend an appliance, such as a lip bumper, when appropriate.
- Professional guidance: If the habit is persistent or is affecting the teeth or bite, a pediatric dentist can assess the child and recommend appropriate treatment.
Key Takeway: Understanding and addressing the trigger behind a habit can be more helpful than repeatedly telling a child to stop.
When Should You Visit a Pediatric Dentist?
Most mild, occasional habits don't need immediate intervention. However, it's worth scheduling a dental visit if you notice:
- The habit continuing regularly despite efforts to help your child stop
- Any of the tooth or bite changes described above
- Persistent gum irritation, redness, or bleeding
- Ongoing lip swelling, chapping, or a visible bite mark on the lip
- Difficulty stopping the habit despite repeated efforts at home
A pediatric dentist can assess whether the habit is affecting the teeth, gums, or developing bite and recommend age-appropriate steps to prevent further problems.
Conclusion
Nail biting and lip biting are common childhood habits, and in many cases, they improve with time, patience, and gentle guidance. The key is recognising when a habit becomes frequent or persistent and starts to affect your child's teeth, gums, lips, or bite.
Early awareness and supportive habit-breaking strategies can help protect your child's oral health as their permanent teeth develop. If the habit persists or you notice changes in the teeth or bite, a pediatric dentist can provide appropriate guidance.
Disclaimer: This blog is for educational purposes and does not replace professional dental consultation.
Frequently Asked Questions (FAQs)
References
- 1.Ghanizadeh, A. (2011). Nail biting; etiology, consequences and management. Iranian Journal of Medical Sciences, 36(2), 73–79.
- 2. Gyra, G. G., Kumar, V. S., & Janakiram, C. (2025). Prevalence of oral deleterious habits among children: A systematic review and meta-analysis. Journal of Oral Biology and Craniofacial Research, 15(6), 1539–1562.
- 3. Kawale, Y. U., Parakh, H., Thosar, N. R., & Chandra, A. (2024). Managing the lower lip-sucking habit with a lip bumper appliance: A pediatric case study. Cureus, 16(7), e65575.
- 4. Katib, H. S., Aljashash, A. A., Albishri, A. F., Alfaifi, A. H., Alduhyaman, S. F., Alotaibi, M. M., Otayf, T. S., Bashikh, R. A., Almadani, J. A., Thabet, A. M., & Alaman, K. A. (2024). Influence of oral habits on pediatric malocclusion: Etiology and preventive approaches. Cureus, 16(11), e72995.
- 5. Otsugu, M., Sasaki, Y., Mikasa, Y., Kadono, M., Sasaki, H., Kato, T., & Nakano, K. (2023). Incompetent lip seal and nail biting as risk factors for malocclusion in Japanese preschool children aged 3–6 years. BMC Pediatrics, 23, 532.
Authored By
BDS, PGCE (Endodontics)
A dentist and dental health educator committed to comprehensive oral care, with a focus on patient education and early intervention. She helps patients understand dental conditions clearly and make informed decisions for timely and appropriate treatment, aiming to maintain long-term oral health and natural teeth preservation.