Cracked, split or damaged night guard?
Updated September 1, 2026 to reflect current guidance on cracked, fractured and damaged night guards, including when repair or replacement may be appropriate.
You take your night guard out in the morning and notice a crack. Or maybe it has split completely in half, developed a sharp edge, lost a piece—or become the latest victim of your dog.
The next question is usually immediate: Can I still wear this tonight, or do I need a new one?
A significantly broken night guard should generally not be worn. If it has split apart, developed sharp or jagged edges, lost a piece, changed shape, or no longer fits securely, stop using it and contact your dentist or guard provider. A faint surface line may be less urgent, but any crack that is spreading or affecting fit deserves evaluation. Do not use household glue or super glue to repair a night guard.
My night guard broke. What should I do?
Start with what the damage actually looks like.
A faint line that does not extend through the material is different from a complete fracture. Check whether the crack is spreading, whether the guard flexes differently, and whether the fit has changed. If you are unsure whether the material is structurally intact, stop wearing it until your dentist or provider can evaluate it.
Once a crack extends through the appliance, the guard may flex, spread, or break further under pressure. Replacement is usually more appropriate than continuing to sleep in it.
A guard that has completely fractured can no longer fit or function as one intact appliance. Do not try to hold the pieces together in your mouth or wear one section by itself.
A sharp edge can irritate or injure the tongue, cheeks or gums. The guard should be evaluated before you continue using it.
Missing material can change the fit and leave additional edges vulnerable to breaking. Loose fragments are another reason not to continue sleeping in the damaged appliance.
A hole is usually a wear problem rather than a sudden fracture. That area no longer provides the same barrier between the opposing teeth. If this keeps happening, the pattern may tell you something about your grinding, clenching or guard construction.
Do not continue wearing a guard that has been chewed, punctured, distorted or broken by a pet—even if you can still force it onto your teeth.
Why did my night guard crack or break?
Night guards are exposed to repeated force, moisture, temperature changes, cleaning and everyday handling. They are durable appliances, but they are not indestructible.
Common reasons for breakage include:
Repeated grinding or clenching
Bruxism can repeatedly load the same areas of an appliance. Over time, that may contribute to thinning, grooves, cracks or eventual fracture.
One area is taking more pressure than the rest
A guard may fail in one location while the rest looks relatively intact. Tooth position, bite contact, dental work and the way the jaw moves can influence where pressure is concentrated.
The material has become significantly worn
A guard that has already thinned or developed deep wear may have less material remaining to withstand additional force.
Heat or accidental damage changed the appliance
Very hot water can distort some thermoplastic dental appliances. Dropping, stepping on, bending or improperly storing a guard can also damage it outside the mouth.
The appliance has simply experienced a lot of use
No dental guard lasts forever. But rather than turning this page into another lifespan guide, we cover expected longevity separately in How Long Do Dental Night Guards Last?
Can I keep wearing a cracked night guard?
It depends on what you mean by “cracked.”
A faint surface line
A superficial line that has not spread through the appliance may not mean the guard has completely fractured. Still, monitor it closely and pay attention to any change in flexibility, comfort or fit.
A true crack through the material
If you can see or feel that the material has separated, the guard flexes at the crack, an edge has lifted, or the fit has changed, discontinue use and have it evaluated.
When in doubt, it is better to have the appliance inspected than to assume a cracked guard is structurally sound because it still fits over your teeth.
DIY repair
Can I glue my broken night guard back together?
We do not recommend repairing a night guard with household glue, super glue, craft adhesive or another DIY bonding product.
There are several problems with attempting a home repair:
- The repaired guard may no longer seat on the teeth the same way.
- An uneven repair can create rough or hard edges.
- The bond can fail again under grinding or clenching forces.
- A household adhesive may not be intended for prolonged use inside the mouth.
A custom guard depends on its shape and fit. Even if the pieces appear to line up on the kitchen counter, that does not mean the repaired appliance will behave the same way on your teeth.
Can a broken night guard be professionally repaired?
Sometimes, but it depends heavily on the appliance and material.
Certain dental acrylic appliances may be repairable by a dental laboratory. Many modern thermoformed night guards, however, are generally replaced after a significant fracture because restoring the original shape, fit and strength may not be practical.
What if I wore a hole through my night guard?
A hole is related to this page, but it represents a somewhat different problem from a sudden crack or fracture.
If your teeth have gradually worn through the same area, the appliance has experienced repeated contact at that location. If this has happened more than once, simply replacing it with the exact same construction may not answer the bigger question.
We recently consolidated our guidance on this into: Why Do I Keep Grinding or Wearing Through My Night Guard?
That guide focuses specifically on recurring holes, deep grooves, concentrated wear, material choice and thickness.
Does a broken night guard mean my grinding is getting worse?
Not necessarily.
A guard can break because of accumulated wear, accidental damage, heat, concentrated bite contact, material characteristics or repeated grinding and clenching.
One broken appliance therefore does not prove that your bruxism has suddenly become more severe.
What deserves more attention is a pattern: multiple guards cracking, thinning or developing holes in a relatively short period, especially when damage appears in similar locations.
In that situation, save the damaged appliance and show it to your dentist or guard provider. The wear pattern can be useful when discussing whether the fit, material, thickness or design should change.
Yes, this happens a lot
What if my dog chewed or ate my night guard?
Dogs seem to have an unfortunate talent for finding dental appliances.
If the guard has been chewed, punctured, cracked, distorted or has pieces missing, do not put it back in your mouth. Damage can change the shape and fit even if part of the appliance still looks usable.
If you believe your pet swallowed part or all of the guard, contact your veterinarian for advice. The appropriate next step depends on the size of the animal, the amount swallowed and whether the appliance contained any other components.
Tonight's practical question
My night guard broke. Can I sleep without it tonight?
For most people using a night guard to protect against routine grinding or clenching, a damaged appliance should not be made “safer” by gluing it together or wearing a fractured piece simply because you do not want to miss a night.
If the guard is significantly broken, sharp, unstable or no longer fits correctly, contact your dentist or provider about replacement rather than continuing to use the damaged appliance.
We cannot determine from an article what the consequences of going without a particular appliance would be for an individual. If your dentist prescribed the guard for a specific dental or medical reason, or you have extensive dental restorations that require protection, follow your dentist's individualized guidance.
When should I replace a broken night guard?
This page deals with obvious structural damage. A guard that is split, missing pieces, sharply fractured, significantly distorted or worn completely through in an important contact area usually needs professional evaluation for replacement.
But we deliberately do not want this page competing with our full replacement guide.
If your guard is intact and you're trying to decide whether normal wear, age, discoloration or fit changes mean it's time for a new one, go to: When Should You Replace Your Night Guard?
And if your question is simply how many months or years a guard should typically last, see: How Long Do Dental Night Guards Last?
Need a replacement night guard?
If your damaged guard needs replacing, Sentinel Mouthguards offers custom-fit options in different materials and thicknesses. Compare the options to find one that suits your needs, and follow your dentist's guidance if they have recommended a particular type of appliance.
Already a Sentinel customer? Contact us before placing a replacement order. We can check whether your impression or digital scan is on file and whether your damaged guard may qualify for warranty coverage. Let us know about any dental work or changes to your teeth since your last order.
What about cracks, wear and microplastics?
If a guard is heavily worn or physically breaking apart, its condition alone is a reason to have it evaluated—you do not need to diagnose microscopic particle release by looking at it.
If your concern is specifically about current research on particle release from dental polymers, we cover that separately in: Do Night Guards Release Microplastics? What Current Research Actually Shows
Keeping that science on its own page lets this article stay focused on the question you came here with: what to do about a guard that is physically damaged right now.
Frequently asked questions
What should I do if my night guard cracked?
Inspect the crack closely. If it extends through the material, causes the guard to flex, creates an edge, or changes the fit, discontinue use and contact your dentist or guard provider. A faint superficial line may be less urgent, but it should still be monitored.
How do I fix a broken night guard?
Do not attempt to repair it with household adhesives. Depending on the material and type of appliance, a dental professional may determine that repair is possible, but many significantly fractured thermoformed night guards are replaced rather than repaired.
Can I use super glue on my night guard?
No. A household glue can alter fit, create rough surfaces and introduce a material that was not selected for prolonged intraoral use. Ask the dentist, laboratory or manufacturer that made the guard about the appropriate replacement or repair process.
What if my night guard broke in half?
Do not continue wearing it. A guard that has completely fractured can no longer function as one intact appliance and should be evaluated for replacement.
Is it dangerous to wear a broken night guard?
Significant damage can create sharp edges, loose material, a poor fit or reduced coverage. For that reason, a substantially fractured guard should not simply be worn as though nothing changed.
Why did my night guard break so quickly?
Repeated grinding or clenching, concentrated bite contact, prior thinning, heat distortion, accidental damage and appliance construction can all contribute. If guards repeatedly fail quickly, have the pattern evaluated rather than assuming every break has the same cause.
My dog ate my night guard. Can I reorder from the same impression?
That depends on the company that made your guard and whether your impression or digital scan is still available. If the guard came from Sentinel Mouthguards, contact us and we can check whether your impression or digital file is still on record.
Dental reference
This article is for educational purposes only and is not intended to diagnose a dental condition or replace individualized advice from your dentist or healthcare professional.