Why is Nail Biting Harmful to Children's Teeth?

Nail biting can damage children's teeth. We'll tell you about the consequences of this habit in children's mouths in the following article.

Written and verified by the dentist Vanesa Evangelina Buffa.

Last update: 04 July, 2024

Did you know that when children have the habit of compulsive nail biting, they can damage their teeth? In addition to hurting their fingers, children with this habit known as “onychophagia” suffer consequences in their oral health.

Putting their fingers in their mouths and nibbling their nails is usually an unconscious action. Many children do it to channel an emotional conflict, to calm anxiety, out of boredom, or as a behavior that’s imitated. Although this habit may seem harmless, it can damage the mouth. Keep reading and find out why this habit is harmful to your child’s teeth.

Onychophagia in children

Onychophagia is the name given to the habit of nail biting. It’s a compulsive and unconscious behavior in which the person puts their hands in their mouth and nibbles the end of their fingers.

Although it’s a habit that occurs at any time of life, an article in the Scientific Journal of Dentistry UNITEPC points out that it’s common in children, adolescents, and young people. The same text indicates that it’s usually a temporary habit and its status as pathological behavior depends on the frequency, intensity, and duration.

The origin of onychophagia has been related to stress, anxiety, or nervousness. In situations that produce anxiety in children, the gesture and the action of putting their nails in their mouth would serve as a stress reliever and pleasure mechanism.

In fact, a study published in the Iranian Journal of Medical Sciences links nail biting to moments of boredom or to having to solve a difficult problem.

The consequences of nail-biting in children

In addition to the obvious damage that children suffer to their nails and the skin surrounding them, onychophagia causes consequences at the oral level. Both teeth and other oral structures are susceptible.

To understand the damage that nail biting can cause to children’s teeth, it’s important to consider that hands are always in contact with foreign substances and pathogens. With these extremities, little ones relate to the world around them and, in many moments, they get dirty and contaminated.

Viruses, bacteria, parasites, and other dirt that remain on the hands enter the mouth during the act of biting the nails. At the same time, there’s also a mechanical action on the tooth surfaces that can wear away the enamel and even inflame the gums. Let’s take a closer look at some of the consequences of onychophagia on the oral health of children.

Wearing down tooth enamel

When children bite their nails repeatedly and constantly, they exert excessive pressure on their teeth. This friction of the nails against the teeth wears away the tooth enamel, which is the outermost protective dental tissue.

Over time, premature and continuous loss of enamel causes sensitivity and increases the risk of cavities. The central incisors are the most affected teeth, due to their position and exposure to the habit.

Increased risk of cavities

Cavities are one of the most frequent diseases of the mouth. Their development is usually associated with poor oral hygiene that causes excessive bacterial colonization, responsible for the fermentation of dietary carbohydrates. This metabolism produces acids that demineralize the hard tissues of the tooth.

According to a study that analyzed the prevalence of cavities in children with onychophagia, nail biting increases the risk of children developing this disease in their teeth for different reasons.

• Enamel wear: As we’ve already mentioned, the absence of this protective layer increases the susceptibility of the teeth to demineralization.
• The transfer of bacteria that accumulate on the nails to the mouth: The increase of germs in the mouth alters the normal flora, favoring the growth of cariogenic bacteria.
• The permanence of nail fragments between the teeth: Their removal is difficult despite brushing or flossing, which favors the accumulation of bacteria in the area.

Occlusion problems

The habit of nail biting involves the application of constant and repetitive forces on children’s teeth. This pressure can alter the growth of the jaws and the alignment of the teeth, causing bite and malocclusion problems.

According to an article published by the Indian Journal of Dental Research, crowding and incisor rotations are the problems most associated with this habit.

Damage to the gums

Onychophagia not only affects children’s teeth, but the gums are also at risk. Fingernails can injure, cut, and cause wounds to the gingival tissues. This causes inflammation of the area, discomfort, and even infections due to the entry of bacteria present on the hands.

Some mouth sores can be related to trauma to the mucosa and its colonization by microorganisms. These are painful but self-limited ulcerations that resolve within a week.

Bad breath

Bad breath in children is usually due to the presence of bacteria in the mouth and inadequate oral hygiene. As mentioned, nail biting favors the entry of germs into the mouth, which increases the bad odor.

Risk of infections

When children bite their nails, the germs present enter their mouths, increasing the risk of infections. But infections aren’t only caused by bacteria, it’s also possible for viruses and fungi to enter the mouth. Cold sores or warts, for example, can be contracted by direct contact with the virus.

In fact, a case-control study that looked at risk factors for common human papillomavirus (HPV) infections in children found that onychophagia is the main predisposing factor for the development of common warts on the face, hands, and oral cavity.

Temporomandibular disorders

The temporomandibular joint suffers from the effects of onychophagia. The constant mechanical stress caused by chewing can alter its function. This causes pain when chewing and abnormal jaw movements.

Solutions to stop nail biting and take care of children’s teeth

You can explain to your child the risks and consequences of nail biting and the need to stop this habit. Talk to them about the importance of keeping their mouth healthy and how onychophagia damages their teeth.

You can also help your child identify situations or emotions that lead to nail biting. Does your child bite when they are stressed, bored, or nervous? Try to find out what triggers this behavior.

Other times, seeking professional help may be appropriate. A child psychologist can address the habit and treat anxiety, depression, or stress that may be the background of onychophagia.

Until your child manages to eradicate the habit, keeping nails short and hands clean is a measure that will reduce the negative effects on the mouth. It’s also a good idea to make an appointment with your pediatric dentist to check for oral damage and address it.

More than just a bad habit, it’s a health risk

Nail biting is more than just a bad habit. It poses a real risk to children’s oral health, affecting not only the appearance of their teeth, but also their overall well-being. Addressing this behavior early and promoting good oral health from an early age is essential in order to ensure proper dental development and prevent future problems.

Finally, remember that each child is unique, and eliminating nail biting may require different approaches. Your guidance, patience, and perseverance will help your child overcome onychophagia and take care of their smile.