Updated on February 1, 2024
5 min read

Craze Lines in Teeth: Causes and Treatment

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What are Craze Lines in Teeth?

If you’ve noticed small lines running through your front teeth, you may be worried that something is wrong. But what you’re seeing are most likely craze lines, which are harmless imperfections in your enamel.

These vertical lines are sometimes a sign of aging, as enamel tends to become harder and thinner over time. In other cases, they’re caused by habits like teeth grinding and nail-biting.

If you want to reduce or eliminate the appearance of craze lines, you have some options. However, they don’t necessarily affect the function or health of your teeth.

Craze Lines and Dental Health

Craze lines generally aren’t a sign of anything troublesome for your dental health. However, they may indicate habits such as bruxism or nail-biting.

While craze lines won’t affect the overall health of your teeth, these habits can. They can increase the likelihood of tooth fractures and tooth sensitivity.

Do Craze Lines Weaken Teeth?

No, craze lines don’t weaken your teeth. They are harmless cosmetic issues that don’t impact your oral health.

Craze Lines vs. Cracked Teeth

Craze lines are superficial cracks that only affect the enamel. They’re not what people usually mean when they refer to cracks in teeth.

Beneath your enamel, your teeth have two more layers:

  • Dentin, which makes up most of your teeth
  • Pulp, where nerves and blood vessels are

A “true” tooth fracture is a crack in the dentin and possibly the pulp. It may be painful and is at risk of getting worse if not treated as soon as possible. Cracked teeth may require crowns, root canals, or other treatments.

Craze lines, on the other hand, aren’t painful. They generally don’t come with any other symptoms and don’t require treatment. They’re mainly cosmetic issues.

Can Craze Lines Lead to Cracked Teeth?

In general, no. Craze lines mainly affect the outer enamel. If they grow, they’re more likely to spread over the surface of a tooth rather than deeper into it.1

What Do Craze Lines Look Like?

Craze lines look like tiny hairline cracks on your enamel. They appear as shallow, straight vertical lines.

Craze lines can sometimes appear yellow, gray, or brown. In other cases, they’re translucent and barely noticeable (unless you look closely or dry the teeth).

You can easily see craze lines if you flash a light on your teeth at a particular angle. The light will reflect off the surfaces of the hairline cracks.

image 2

What Causes Craze Lines?

Craze lines are often a harmless sign of aging, resulting from a lifetime of wear and tear on your enamel.

Your teeth are exposed to stress throughout the day, every day. Decades of biting, chewing, brushing, and temperature changes will cause your enamel to become more brittle and thinner.

These gradual changes can lead to the formation of craze lines. However, craze lines may be more likely because of certain habits or conditions. These include:

  • Clenching or grinding your teeth and jaw — When you clench your teeth, your lower and upper teeth are forced together, causing pressure that can lead to craze lines.
  • Nail biting and other bad habits — Biting your nails, chewing on objects, or using your teeth to open bottles may contribute to craze lines.
  • Eating frozen foods — Biting into frozen foods or chewing ice cubes instead of sucking the ice can cause craze lines.
  • Uneven bite — An unstable or uneven bite due to misaligned teeth can cause craze lines. Teeth might not meet where they should when your mouth is shut.

These can all repeatedly add to the daily pressure on your teeth. This may cause your enamel to develop more craze lines or develop them faster.

Can You Get Rid of Craze Lines?

While craze lines don’t threaten oral health, they can be a cosmetic issue. If you want to make craze lines less visible, you have several options:

Teeth Whitening

Whitening your teeth is one way to reduce the appearance of craze lines. You may choose to:

These whitening treatments lift any stains within the craze lines that may make them darker. They can also improve the appearance of your teeth overall.

Dental Bonding

Another option is to have your dentist fill the craze lines with composite resin. This is called dental bonding and is a relatively fast procedure.


The most “complete” way to improve teeth with craze lines is also the most expensive. Veneers are shell-like covers that fit over the surface of your teeth.

Veneers can be made of porcelain or composite resin. They offer the benefit of completely transforming the appearance of your teeth, and they can last for years if taken care of. However, they tend to be costly.

Tips for Preventing Craze Lines

Some degree of change to your enamel may be inevitable with age. However, there are some things you can do to lower the likelihood and visibility of craze lines:

  • Brushing the teeth thoroughly but gently to minimize stains in craze lines
  • Stopping bad habits like nail-biting and opening bottles with the teeth
  • Avoiding chewing very cold or frozen foods like ice cubes
  • Using a night guard or mouthguard to protect against teeth grinding
  • Avoiding staining foods or beverages like red wine and coffee, as they can make craze lines more visible
  • Avoiding tobacco products, which can also stain your teeth, to reduce the visibility of craze lines

These things may not guarantee that craze lines never form, but they will do a lot to preserve the health and appearance of your teeth over time.


Craze lines are shallow vertical cracks in the outer layer of your tooth enamel. They may be translucent, though tooth staining can make them darker.

While you may not like how craze lines make your teeth look, they’re usually nothing to be concerned about. They become more likely with age as your enamel weakens. Certain habits, such as nail biting or teeth grinding, can also contribute to them.

Cosmetic treatments like teeth whitening can make craze lines less visible. Talk to a dentist about your options.

Last updated on February 1, 2024
7 Sources Cited
Last updated on February 1, 2024
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.

We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
  1. Yahyazadefar, Mobin, et al. “On the Importance of Aging to the Crack Growth Resistance of Human Enamel.” Acta Biomaterialia, 2016.
  2. Dabuleanu, Mary, and Alexander Suham. “How does one decide whether a crack/craze line on an asymptomatic tooth should be attempted to be removed, either with a restoration or a crown?” Canadian Dental Association, 2014.
  3. Krell, Keith V., and Eric M. Rivera. “A Six Year Evaluation of Cracked Teeth Diagnosed With Reversible Pulpitis: Treatment and Prognosis.” Journal of Endodontics, 2007.
  4. Mariona, Preethi, and Anthony Delphine. “Diagnostic Methods for Cracked Tooth by Two Endodontic Tools.” Drug Invention Today, 2018.
  5. Mutlu, Ozcan, et al. “Bleaching Induced Tooth Sensitivity: Do the Existing Enamel Craze Lines Increase Sensitivity? A Clinical Study.” Odontology, 2014. 
  6. Zidane, Bassam. “Recent Advances in the Diagnosis of Enamel Cracks: A Narrative Review.” Diagnostics (Basel, Switzerland), 2022.
  7. Yu, Mingyue, et al. “Diagnosis of cracked tooth: Clinical status and research progress.” Japanese Dental Science Review, 2022.
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