Question: My mom gives me such a hard time about biting my fingernails; she says it’s going to ruin my teeth. My teeth look fine, so what’s the big deal?

Answer: Nail biting, also known as onychophagia, is one of the most common habits among children, teens and young adults.  Nail biting is generally triggered by stress, excitement, boredom, inactivity or can even be a learned behavior from family members. 

According to the Academy of General Dentistry about 30% of children between ages 10 - 18 and about 15% of adults bite or chew their nails.   Nail biting occurs most during puberty.  Boys bite their nails more often than girls after the age of 10 and most people stop biting their nails by age 30.

Fingernails are almost twice as dirty as fingers.  They harbor bacteria and germs even after average hand washing.  Nail biting can transfer pinworms or bacteria buried under the surface of the nail to your mouth.  .

Braces and nail biting don’t mix either. Traditional orthodontic treatment (wires & brackets) is already putting pressure on teeth, nail biting adds unnecessary additional pressure, stressing your teeth and weakening roots.  Not to mention the wires and brackets can become bent or broken.

Perhaps the worst effect of nail biting on teeth is that it can cause teeth to chip, break and wear unnecessarily.  Nails are tough and hard, so when you bite down on them you are causing excess stress to your teeth. Over time this weakens teeth and eventually results in chipping or breaking.  Front teeth are designed for cutting – not chewing and are not strong enough to be in constant use. Nail biting causes nearly constant chewing, wearing teeth down faster than those of a non-nail biter.  This constant stress and pressure contributes to malocclusion of the anterior teeth. 

Nail biting also can cause injury to the gums.  A bitten nail tearing into gum tissue can cause further weakening of the teeth as well as disease. When bitten-off nails are swallowed, stomach problems can develop.

What you can do about it:

  1. Using a bitter tasting polish on your nails may discourage biting.  There are a number of brands available. Ask your dentist to recommend one that her/his patients have had success with.

  2. Keeping nails trimmed, filed and attractive can encourage against biting and chewing.

  3. A special mouth guard may help patients to break the habit.  Some people find it more of a hassle to take the guard out to bite their nails.  Your dentist can make one for you that custom fits over your teeth and is barely noticeable.

  4. If you are considering orthodontic treatment you may want to look into Invisalign.  The clear aligners (besides being nearly undetectable) would make it very difficult to bite your nails while giving you a more beautiful smile. 

  5. A diet rich in foods with calcium and magnesium can help nails repair and grow well.


    According to the Academy of General Dentistry (AGD) nail biting can result in significant additional dental bills over a lifetime.  Now that you know how harmful and costly nail biting can be, it’s time to take action to break your nail biting habit. 


    Dr. Deborah Petronio is the owner of Aurora Dental Care.  If you have any further questions or concerns regarding this or any dental subject, please contact her at 716-652.0190 or