Short answer
- A mouth guard for bruxism is a removable appliance worn over the teeth. It is also called a night guard, a dental guard, or an occlusal splint.
- Its job is protection, not cure. The guard separates the upper and lower teeth and spreads biting force, so grinding wears the guard instead of the tooth surfaces. It does not cure bruxism and does not reliably stop grinding itself.
- There are three generic types. Stock guards come preformed. Boil-and-bite guards are softened in hot water and molded to the mouth at home. Custom guards are made by a dentist from impressions or scans of your own teeth.
- Fit is the central safety issue. A loose, bulky, uneven, or sore guard can irritate the gums, change how the bite feels, or add to jaw pain. The National Institute of Dental and Craniofacial Research advises stopping use and consulting a dentist or doctor if an intraoral appliance causes pain.
- A dentist-fitted guard involves clinical judgment, not just a mold. A dentist examines the teeth and jaw first, checks that the bite is even on the guard, and reviews the fit over time.
- Evidence for symptom relief is limited. A 2020 systematic review in the British Dental Journal found very low certainty evidence on oral splints for bruxism and jaw disorders. Protection is the honest reason to wear one, not a promise of pain relief.
- See a dentist if grinding has damaged or sensitized your teeth, if you have jaw, face, or ear pain, or if a partner reports grinding in your sleep. Those are the NHS thresholds for seeking dental advice.
Introduction
“Gum shield” is the term commonly used in the United Kingdom for a removable appliance that fits over the teeth. In the United States the same kind of device for teeth grinding is usually called a mouth guard, a night guard, or a dental guard, and dentists may also use the terms occlusal splint or bruxism splint. This article uses mouth guard and night guard as the main terms, because it is written in US English.
A guard for bruxism does one main job. It puts a physical barrier between the upper and lower teeth so that, when you clench or grind, tooth surfaces do not rub and press directly against each other. That barrier can protect enamel, fillings, and crowns from further wear. What a guard does not do is just as important. A guard does not cure bruxism, and it does not reliably stop the jaw muscle activity that causes grinding.
This article explains what bruxism is, how sleep and awake bruxism differ, what a guard can and cannot do, and the three generic types of guard: stock, boil-and-bite, and custom-fitted by a dentist. It also covers night and day guards, why a retainer is not the same thing, how bruxism relates to jaw joint pain, the risks of an ill-fitting guard, how a fitted guard is made and looked after, and the signs that mean a dentist, rather than a new guard, is the next step. It is general information only. It does not diagnose bruxism in any individual reader, and the right guard for a particular mouth can only be chosen after a dentist has examined the teeth, the bite, and the jaw.
If you have a locked jaw, severe jaw or face pain, a broken or loose tooth, or swelling, seek dental care promptly rather than waiting to see whether a guard helps.
What Bruxism Is
Bruxism is repetitive jaw muscle activity that involves clenching or grinding the teeth, or bracing or thrusting the jaw. It is not chewing, and the forces can be considerable.
Sleep bruxism
Sleep bruxism happens during sleep. Mayo Clinic describes it as a sleep-related movement disorder that may be linked with brief disturbances during sleep. Symptoms tend to be worst on waking: a tired or tight jaw, a dull headache starting at the temples, and sore or sensitive teeth in the morning.
Awake bruxism
Awake bruxism is more often clenching than grinding, and it is commonly linked with concentration and with emotions such as anxiety, stress, anger, frustration, or tension. Because it happens while a person is awake, awareness and habit change matter more for this pattern, and a guard, if one is used, is a thinner daytime design rather than a night guard.
Causes and associations
The exact cause is not fully understood. Mayo Clinic describes bruxism as likely due to a mix of physical, mental health, and genetic factors. The NHS lists factors it is often linked to: stress and anxiety, which it calls the most common cause of teeth grinding; sleep problems such as snoring and sleep apnea; medicines taken for sleep problems, depression, or anxiety; smoking; and drinking a lot of alcohol or caffeine. An association is not a diagnosis. Nor is the older idea that a “bad bite” causes grinding well supported: the National Institute of Dental and Craniofacial Research states that research does not support the belief that a bad bite or orthodontic treatment causes temporomandibular disorders.
Signs that grinding may be happening
The NHS lists, as well as grinding and clenching itself, a painful jaw, worn down or broken teeth, increased sensitivity, loss of teeth and fillings, headaches, earache, and disturbed sleep. Mayo Clinic adds teeth that are flattened, fractured, chipped, or loose, worn enamel, tired or tight jaw muscles, pain that feels like an earache although the ear itself is fine, and a jaw that pops, clicks, or locks. None of those signs alone proves bruxism: worn teeth can also reflect acid erosion, and jaw pain and headaches have many causes.
What a Guard Can and Cannot Do
A guard can do three things, all mechanical. First, it separates the teeth, so enamel no longer grinds against enamel and a filling or crown no longer takes the full force of the opposing tooth directly. Mayo Clinic puts it plainly: splints and mouth guards keep the top and bottom teeth separated while sleeping, and this can stop the damage caused by clenching and grinding. Second, it spreads force: a well made guard gives the bite an even surface to meet, so force is shared across many contact points instead of concentrating on one tooth. The British Dental Journal systematic review lists spreading the forces placed on individual teeth among the proposed mechanisms of oral splints, along with protection of the teeth and jaws. Third, it takes the wear itself, and its wear pattern shows a dentist where the load is falling.
A guard cannot cure bruxism. The muscle activity continues, and a person can grind just as actively against a guard as against their own teeth; the difference is what gets damaged. Mayo Clinic notes that dental methods may prevent or correct wear even though they may not stop bruxism itself.
Nor can it be relied on to relieve pain. The 2020 systematic review by Riley and colleagues in the British Dental Journal found the randomized trial evidence on oral splints for temporomandibular disorder and bruxism to be of very low certainty. It did not demonstrate that splints reduced pain in temporomandibular disorders as a group, and there was insufficient evidence to determine whether splints reduce tooth wear in bruxism, because no included trial had measured tooth wear. The reason to wear a guard is therefore protection, rather than a guaranteed effect on pain or grinding frequency, which the trials have not established.
A guard also cannot treat the factors that accompany grinding, or repair damage already done. Stress, poor sleep, snoring, and possible sleep apnea each need their own assessment. Flattened, cracked, or sensitive teeth and damaged restorations need dental assessment and, in some cases, repair. Our guide to grinded teeth repair options and what to expect from a dentist explains that repair side of care, which is separate from prevention with a guard.
The Three Generic Types of Guard
The American Dental Association, through its MouthHealthy patient site, describes three types of mouthguard. Its descriptions were written with sports protection in mind, so the fit lessons carry over but the purpose differs: a bruxism guard is designed for hours of nightly wear and grinding forces, not for a single impact.
| Type | How it is made | Fit characteristics | Main limitations for bruxism |
|---|---|---|---|
| Stock | Preformed, in a standard shape, ready to wear | Often does not fit well, and can be bulky | Can make breathing and talking difficult, may need the mouth held closed to stay in place, rarely gives an even bite |
| Boil-and-bite | Softened in hot water, then adapted to the shape of the teeth as it cools | Usually a better fit than a stock guard | Fit depends on following the molding instructions exactly; it can end up thin where force is greatest, uneven, or loose |
| Custom-fitted | Made by a dentist from impressions or digital scans of the individual mouth | Individually created for fit and comfort | Requires dental appointments and later review; the fit changes if the teeth change |
Stock guards
A stock guard comes preformed: you do not shape it, and it is not shaped for you. The ADA notes that stock guards often do not fit very well, can be bulky, and can make breathing and talking difficult. For bruxism that matters. A guard that will not stay in place during sleep may be displaced or removed unconsciously, or held in place by biting, which adds muscle work instead of reducing load.
Boil-and-bite guards
A boil-and-bite guard starts as a preformed shape in a thermoplastic material. It is softened in hot water, inserted, and allowed to adapt to the shape of the mouth. The ADA notes that this usually offers a better fit than a stock guard, and stresses following the manufacturer’s instructions.
Custom-fitted guards
A custom guard is made for one mouth. The dentist takes impressions or a digital scan, the guard is fabricated to that model, and at a fitting appointment the dentist checks retention, comfort, and how the teeth meet on it, and adjusts it. The ADA describes custom-made guards as individually created for fit and comfort. The NHS makes the same point: a dentist may recommend a mouth guard or mouth splint, worn at night to protect the teeth from damage, made to fit precisely over the upper or lower teeth. Custom fitting also lets the dentist choose which arch the guard covers, typically the upper teeth, how thick it is, and how hard or soft the material is, based on the pattern of grinding, existing restorations, and jaw symptoms. That clinical reasoning, rather than the material alone, is the main difference from a ready-made guard.
Night Guards, Day Guards, and Retainers
A night guard is the most common form of bruxism guard, because sleep is when a person cannot monitor their own clenching. Night designs are built for hours of wear and repeated grinding, so they are generally more substantial than daytime designs, and a night guard is worn only during sleep unless a dentist advises otherwise.
A day guard addresses awake clenching. Because the wearer needs to speak and work, day designs are usually thinner and less obtrusive, with a trade-off in durability.
A retainer is not a guard. A retainer holds teeth in position after orthodontic treatment, and an aligner is made to move teeth. Neither is designed to absorb grinding forces, and neither has the thickness or bite design a guard needs. Grinding on a retainer can wear or crack it, after which it may no longer hold the teeth as intended. The ADA advises people with a retainer or other removable appliance to talk to their dentist or orthodontist about the right protection. Some people need a combined appliance or separate devices, a call only the treating dentist or orthodontist can make.
Bruxism, Jaw Joint Pain, and TMJ
Readers often search for a “TMJ guard” as though it were a separate product. It is not a separate category. TMJ is the name of the joint itself, the temporomandibular joint, one on each side of the jaw in front of the ears. The disorders are called temporomandibular disorders, or TMDs: the National Institute of Dental and Craniofacial Research describes them as a group of more than 30 conditions causing pain and dysfunction in the jaw joint and its muscles.
Where jaw symptoms are linked with clenching and grinding, a dentist may include an intraoral appliance in a broader, conservative plan. NIDCR describes these appliances as devices that fit over the teeth, protect the teeth, and may help with habit reversal such as jaw clenching; they are also known as nightguards, splints, stabilization appliances, occlusal splints, and bruxism splints. NIDCR is equally clear about the limits: there is not a lot of evidence on whether they improve TMD pain, the appliance should not be designed to permanently change the bite, and if it causes pain you should stop using it and consult your dentist or doctor.
NIDCR also recommends simple, reversible steps first for jaw discomfort: soft foods, heat or cold with gentle jaw exercises, over-the-counter pain relief where appropriate, and reducing jaw clenching, gum chewing, and nail biting. Persistent jaw locking, severe pain, or a clear change in how the teeth fit together needs clinical assessment in its own right. Our fuller guide to TMJ symptoms, causes, and treatment, and how much symptoms vary sets out that wider picture, and it is the better starting point if jaw pain, rather than tooth wear, is your main problem.
Fit, Comfort, and Safety: The Risks of an Ill-fitting Guard
Most problems attributed to guards are problems of fit, hygiene, or review, rather than problems with the idea of a guard itself.
Pain is a stop signal, not a settling-in period. NIDCR advises that if an intraoral appliance causes pain, you should stop using it and consult your dentist or doctor. New tooth or jaw pain, or pain worse on waking than before the guard, should not be pushed through for weeks on the assumption that the mouth will adapt.
The bite should not change. A guard should not be designed to permanently change your bite. A lasting change in how the teeth meet after the guard is removed in the morning, or a feeling that one tooth now hits first, is a reason for review, not self adjustment.
Gums can be irritated by edges and by trapped plaque. A guard sits close to the gumline for hours. A rough edge can rub the gum, and an uncleaned guard worn over unbrushed teeth can hold plaque against the teeth and gums overnight. Soreness after starting a guard has two explanations that need separating: a fit problem, and gum disease developing independently. If gums swell, do not simply stop wearing the guard and ignore it. Clean the guard as directed, brush at the gumline, and ask a dentist to review the fit and the gums. Our guide to how to reduce gum swelling, what helps and what to avoid explains the gum side, and our guide to the signs of gum disease explains which gum changes need assessment in their own right.
Teeth and restorations can be loaded unevenly. A guard that contacts heavily on one tooth and barely on others concentrates force rather than spreading it, which can leave a tooth sore and risks damage to the tooth or a restoration on it. The value of the appliance is the evenness of its contacts, and evenness cannot be judged reliably by feel alone at home.
A loose guard is not a safe guard. A guard that moves, tips, or falls out during sleep is not providing the protection it was worn for, and dental work or a new crown can make a previously good fit inaccurate. Children and teens need closer review still, because, as the ADA notes, their mouths are still growing and changing, so a guard that fit last year should not be assumed to fit now.
Do not modify a guard yourself. Trimming an edge or reshaping a guard in hot water at home can remove exactly the material that was spreading force. Adjustments belong with the dentist, who can check the bite afterward.
Sleep Apnea Is a Different Problem With a Different Appliance
Because sleep bruxism is linked with snoring and sleep apnea in NHS guidance, the two are often confused, and the appliances are sometimes confused with them. They are not interchangeable. A bruxism guard protects teeth. It does not hold the jaw forward and is not designed to keep an airway open. An oral appliance for sleep apnea is a different device, prescribed and monitored in a medical and dental pathway. Our explainer on sleep apnea oral appliance therapy describes that separate category of care.
Mayo Clinic notes that if a dentist suspects bruxism is likely caused by major sleep problems, the recommendation may be to see a sleep medicine specialist, who can carry out a sleep study that can also check for teeth grinding during sleep. Loud snoring, witnessed pauses in breathing, and marked daytime sleepiness are reasons to raise sleep with a doctor directly.
Does Chewing Gum Help With Clenching?
No, not as a treatment, and for people with jaw symptoms it can make things worse. Chewing gum is jaw muscle work, repeated for as long as the gum is chewed, and a jaw already overworked by clenching is unlikely to be trained to relax by adding more work. The NHS says not to chew gum or eat hard foods if you have tooth or jaw pain. NIDCR lists reducing gum chewing alongside reducing jaw clenching and nail biting in its self management advice for jaw disorders. Gum may feel like a distraction in the moment, but it protects no tooth surfaces and does not address the habit.
Getting a Guard Fitted: What to Expect
A fitted guard begins with an examination, not with a mold. Based on the approach described by Mayo Clinic, a dentist evaluating bruxism checks for tenderness in the jaw muscles and joints, stiffness or pain when the jaw moves, and dental changes such as flattened, broken, or missing teeth and damage to the inside of the cheeks. X-rays may be needed. The dentist will also ask about dental health, medicines, daily routines, and sleep habits, because those answers influence both the likely cause and the design.
Once a guard is decided on, the usual steps are impressions or a digital scan, fabrication from that record, and a fitting appointment at which the dentist checks that the guard seats fully, stays in place, feels tolerable, and presents an even bite, and adjusts it until it does. Ask before you leave how long to wear it, how to clean it, what early discomfort is expected and what is not, and when the fit will be reviewed. Bring the guard to later appointments so it can be checked against any change in your teeth. If anything beyond a guard is proposed, particularly anything that would permanently change the teeth or the bite, NIDCR advice is to ask about simpler treatments first, ask for benefits and risks in detail, and consider a second opinion.
Looking After a Guard
Care is simple. The ADA gives the following care pattern for mouthguards, and it applies equally to a bruxism guard.
- Rinse the guard before and after each use, or brush it with a toothbrush and toothpaste.
- Clean it regularly in cool, soapy water, then rinse thoroughly. Use cool water, not hot.
- Store it in a sturdy container with vents, so it can dry and bacteria are less likely to grow.
- Never leave it in the sun or in hot water. Heat can distort the shape, and a distorted guard is an ill-fitting guard.
- Bring it to regular dental checkups for evaluation, and check it yourself for wear and for fit.
Replace a guard, on dental advice, when it is cracked, worn through, distorted, or no longer fits, and have the fit rechecked after dental work on a covered tooth. The ADA advises replacing immediately if a guard is worn, damaged, or ill-fitting. Brush before wearing it, so plaque is not sealed against the teeth overnight.
When to See a Dentist
The NHS gives a clear set of thresholds. See a dentist if you grind your teeth and have tooth damage or sensitive teeth; if you grind your teeth and have pain in your jaw, face, or ear; if your partner says you are grinding your teeth in your sleep; or if you are worried about your child grinding their teeth. See a doctor as well if you need help with some of the causes of grinding, such as stress, anxiety, smoking, or drinking too much. Mayo Clinic similarly advises seeing a dentist or another healthcare professional if you have symptoms that could be caused by grinding or clenching.
Seek care more promptly if you have a jaw that locks or will not open or close fully, severe or worsening jaw or face pain, a broken, cracked, or loose tooth, swelling of the gum, face, or jaw, a guard that has started to cause pain, or a clear change in how your teeth fit together, which NIDCR notes can be a sign of a temporomandibular disorder.
Frequently Asked Questions
What is a gum shield for bruxism?
A removable appliance that fits over the upper or lower teeth to protect them from grinding and clenching. In the United States it is usually called a mouth guard, a night guard, or a dental guard.
Does a mouth guard stop teeth grinding?
No. A guard separates the teeth and spreads force, so grinding damages the guard rather than the tooth surfaces, but the jaw muscle activity usually continues. Mayo Clinic notes that splints and mouth guards can prevent or correct wear even though they may not stop bruxism.
Is a dentist-fitted guard different from a ready-made guard?
Yes, in fit and in the clinical work around it. A dentist examines the teeth, bite, and jaw first, chooses the arch, thickness, and material for the pattern of grinding, checks that the bite on the guard is even, and reviews it later. A stock guard comes preformed and often fits poorly. A boil-and-bite guard usually fits better, but no one checks the bite on it afterward.
How strong is the evidence that guards help?
Weaker than most people expect. Riley and colleagues, in a 2020 systematic review in the British Dental Journal, found the trial evidence on oral splints for temporomandibular disorders and bruxism to be of very low certainty, with no demonstration that splints reduced pain, and insufficient evidence on whether splints reduce tooth wear, because no included trial measured it.
Can I wear a guard during the day?
Sometimes, but normally a different design. Daytime clenching is usually addressed with a thinner, less obtrusive guard, plus awareness and habit strategies. A thick night guard worn all day can interfere with speech. Ask a dentist which design, if any, suits your pattern.
Can I use my retainer or aligner as a night guard?
Not safely by assumption. A retainer holds teeth in position and an aligner moves them; neither is built to take grinding forces or to present the even biting surface a guard provides, and grinding can wear or crack a retainer so it no longer does its own job. Ask your dentist or orthodontist first.
Why do my gums feel sore since I started wearing a guard?
Common reasons are an edge that rubs the gum, a fit that presses unevenly, or plaque held against the teeth because the guard or the teeth were not cleaned before wear. Gum disease developing independently is another possibility. Clean the guard daily, brush before wearing it, and ask a dentist to review the fit and the gums.
Is a bruxism guard the same as a sleep apnea appliance?
No. A bruxism guard protects tooth surfaces. It does not position the jaw to help keep an airway open, and it is not monitored as a sleep apnea treatment. Because grinding is linked with snoring and sleep apnea, a dentist who suspects a major sleep problem may recommend a sleep medicine specialist and a sleep study.
How do I clean a guard, and when should it be replaced?
Rinse it before and after each use or brush it with a toothbrush and toothpaste, clean it regularly in cool soapy water, and store it dry in a sturdy vented container out of the sun and away from hot water and pets, following ADA care guidance. Have it reviewed or replaced when it is cracked, worn thin, distorted, loose, or no longer fits.
When should I stop wearing a guard and call a dentist?
Stop and call if the guard causes pain. That is NIDCR explicit advice for intraoral appliances. Also call if a tooth becomes painful or feels as though it has moved, if your bite feels different in a way that lasts after the guard is removed, if the guard cracks or stops staying in place, if your jaw locks, or if you develop swelling.
Sources & references
- National Health Service. "Teeth grinding (bruxism)." Describes links with stress and anxiety, sleep problems including snoring and sleep apnea, certain medicines, smoking, and alcohol and caffeine; symptoms including painful jaw, worn or broken teeth, sensitivity, headaches, earache, and disturbed sleep; advice to avoid chewing gum and hard foods when there is tooth or jaw pain; when to see a dentist and when to see a doctor; and that a dentist may recommend a mouth guard or mouth splint worn at night, made to fit precisely over the upper or lower teeth.
- American Dental Association, MouthHealthy. "Mouthguards." Describes the three types of mouthguard, custom-made, boil-and-bite, and stock, their fit characteristics, that mouthguards typically cover the upper teeth, advice on retainers and braces, and care and replacement guidance including rinsing, cleaning in cool soapy water, vented storage, avoiding sun and hot water, and replacing a guard that is worn, damaged, or ill-fitting.
- National Institute of Dental and Craniofacial Research. "Temporomandibular Disorders (TMD)." Describes TMDs as a group of more than 30 conditions, symptoms including a change in how the teeth fit together, conservative first steps including soft foods, heat or cold with exercises, and reducing jaw clenching, gum chewing, and nail biting, and intraoral appliances, also called nightguards, splints, and bruxism splints, which fit over the teeth and protect them, should not permanently change the bite, have limited evidence for improving TMD pain, and should be stopped, with advice sought, if they cause pain.
- Mayo Clinic. "Bruxism (teeth grinding)." Describes awake and sleep bruxism, sleep bruxism as a sleep-related movement disorder, symptoms including flattened, fractured, chipped, or loose teeth, worn enamel, temple headaches, and tired or locked jaw muscles, causes as a mix of physical, mental health, and genetic factors, dental evaluation for bruxism, referral to a sleep medicine specialist where major sleep problems are suspected, and splints and mouth guards that keep the teeth separated while sleeping and may prevent or correct wear though they may not stop bruxism.
- Riley P, Glenny AM, Worthington HV, et al. "Oral splints for temporomandibular disorder or bruxism: a systematic review." British Dental Journal 2020; 228: 191 to 197. A systematic review of randomized trials that found very low certainty evidence, no demonstration that splints reduced pain in temporomandibular disorders as a group, and insufficient evidence to determine whether splints reduce tooth wear in bruxism because no included trial measured tooth wear.
