Can a night guard make TMJ worse?

You started wearing a night guard to protect your teeth and calm your jaw, and now your jaw feels sorer in the morning than it did before. Maybe your teeth also seem to meet a little differently when you take it out. It is a question I hear often in physiotherapy.

Key takeaways

Yes, a night guard can make TMJ symptoms worse for some people. The main risks are a poor fit and a design that lets the bite shift, and in one small study a soft guard raised night-time muscle activity in half of the people who grind (Okeson, 1987). The NIDCR advises stopping any appliance that causes pain and checking in with your dentist (NIDCR, 2026).

• Bite changes such as open bite have been reported after night guard use with any type of guard, and partial-coverage guards need very careful monitoring (Bereznicki et al., 2018).
• In a 2026 trial, soft and hard splints both reduced TMD symptoms over 12 weeks (Park et al., 2026).
• Reviews find small or neutral benefits from splints for TMD, and side effects have been poorly reported (Sorbo et al., 2026; Riley et al., 2020).

Which night guards carry the most risk?

The US National Institute of Dental and Craniofacial Research (NIDCR) groups night guards, splints, stabilization appliances and occlusal splints together as devices that fit over the teeth, protect them and may help with habits such as jaw clenching. According to the NIDCR they do not change the teeth or bite, but it adds a clear warning: if a dentist suggests one, make sure it is not designed to permanently change your bite (NIDCR, 2026).

A stabilization splint is a hard guard that covers all the teeth of one arch. Cleveland Clinic recommends a custom fit from an oral healthcare provider over an over-the-counter guard, since guards you fit yourself likely won't keep your bite in line as well (Cleveland Clinic, 2026).

In a series of cases reported by UK dentists, night guard use was followed by an anterior open bite, where the front teeth no longer meet. The authors concluded that unintended bite changes may be more common than the literature suggests, can happen with any type of appliance, and that partial-coverage appliances require very careful monitoring (Bereznicki et al., 2018).

Anterior repositioning splints hold the lower jaw forward. A review of posterior open bite, where the back teeth stop touching, lists these splints among the treatments where this bite change commonly occurs (Huang et al., 2020).

Is a soft or a hard night guard better for TMJ?

An older study raises a question about soft guards. Ten people with night-time grinding wore a hard and then a soft splint while their jaw muscle activity was recorded. The hard splint significantly reduced muscle activity in eight of them. The soft splint reduced it in only one person and significantly increased it in five (Okeson, 1987). The study is tiny and almost 40 years old.

Newer data is more reassuring for soft guards. A network meta-analysis of 48 randomized trials found that soft stabilization splints lowered pain in muscle-related TMD compared with control, although that evidence was rated very low quality, while hard splints did so with moderate quality evidence (Al-Moraissi et al., 2020). In a 2026 Korean trial with 70 adults, a ready-made soft splint and a custom 3D-printed hard splint both reduced TMD symptoms over 12 weeks, with no significant difference between them. The authors stress this does not prove equivalence (Park et al., 2026).

If your jaw feels worse with a soft guard, ask your dentist whether a hard, fitted splint would suit you better (Okeson, 1987; Al-Moraissi et al., 2020).

Why does my jaw hurt more when I start wearing a night guard?

None of the sources I rely on gives a settling-in period for a new guard. If wearing it hurts, the NIDCR advice is to stop and have it checked rather than wait it out (NIDCR, 2026).

Pain that keeps growing is a different matter. Cleveland Clinic warns that a guard that doesn't fit properly can make the pain worse, and that a guard can make things worse if your bite isn't balanced (Cleveland Clinic, 2026).

A third possibility is a slowly changing bite. A study of 87 people with TMD measured how much the overlap of the front teeth changed after stabilization splint treatment, including cases that developed an anterior open bite, and identified skeletal features that predicted it (Oh et al., 2022). If your jaw also aches mainly on waking, my article on why your jaw hurts when you wake up covers the other common causes.

What does the evidence say about night guards for TMD and bruxism?

A systematic review by Cochrane authors included 37 trials. When all types of TMD were grouped together (13 trials, 1,076 people), there was no evidence that splints reduced pain compared with no or minimal treatment over up to three months, and the certainty of the evidence was very low. The review found no evidence of adverse events, but noted that reporting of side effects was poor (Riley et al., 2020).

For grinding during sleep, a Cochrane review found insufficient evidence that splints treat sleep bruxism itself, while leaving open a possible benefit for tooth wear (Macedo et al., 2007). The NHS says night-time guards protect your teeth from damage (NHS, 2026).

A 2026 overview of 21 systematic reviews by an international team of TMD researchers concluded that most report small beneficial or neutral effects from splint therapy (Sorbo et al., 2026). The NIDCR also says there is not a lot of evidence on whether appliances improve TMD pain. It recommends conservative treatments and avoiding treatments that permanently change the jaw joints, teeth or bite, and it notes that occlusal treatments, which permanently modify the teeth and bite, lack evidence and may make the problem worse (NIDCR, 2026).

As a physiotherapist, I see a guard as one reasonable tool that helps some people, ideally alongside other self-care, and one that deserves regular follow-up.

Signs your night guard no longer fits

Book a check with your dentist if you notice any of these:

• The guard causes pain or makes your existing jaw pain worse (NIDCR, 2026).
• Your front teeth no longer touch when you bite down, although they used to (Bereznicki et al., 2018).
• Your back teeth stop meeting properly after wearing a repositioning splint (Huang et al., 2020).
• You wear a partial-coverage guard and have not had it checked for a long time (Bereznicki et al., 2018).
• You bought a guard that you fitted yourself and your jaw has felt worse since (Cleveland Clinic, 2026).

Try it: the morning bite check

I show this check in physiotherapy to people who wear a guard and are unsure whether something has changed. It does not replace a dental exam.

1. Take your guard out in the morning and give your jaw a few minutes without it.
2. Sit upright, let your tongue rest lightly on the roof of your mouth and close slowly until your teeth just touch.
3. Notice where you feel the first contact. Check whether your back teeth meet evenly on both sides and whether your front teeth touch.
4. For one week, write down each morning how your bite feels and rate your jaw pain from 0 to 10.
5. If your teeth meet differently on several mornings, or your pain score keeps climbing, take your notes to your dentist.

What helps if your guard is causing problems?

In the moment

If the guard is causing pain, follow the NIDCR advice and stop wearing it until your dentist has checked it (NIDCR, 2026). Meanwhile, the NHS suggests you eat soft food such as pasta, omelettes and soup, hold an ice pack or heat pack wrapped in a tea towel to your jaw, whichever feels better, and gently massage the painful muscles (NHS, 2023).

Long term

Apart from when you eat, your teeth should be apart, and the NHS advises against chewing gum or biting your nails (NHS, 2023). The NIDCR lists gentle jaw exercises alongside soft foods and heat or cold as first steps (NIDCR, 2026). You will find routines on our TMJ exercises page, and our night guard alternative page explains what you can do beyond an appliance. If you are not sure whether you grind at all, start with our page on teeth grinding.

How JawBuddy helps

JawBuddy is a digital companion for guided jaw exercises and self-management. JawBuddy Therapy also includes a daily tooth contact check.

It does not replace emergency care or an individual diagnosis from a qualified healthcare professional.

When should you see a doctor?

Call emergency services now

Call emergency services (911 in the US, 999 in the UK) if you have chest pain that spreads to your arms, neck or jaw, or chest pain that feels tight or squeezing (NHS, heart attack, 2026).

Get an urgent appointment

Contact your doctor urgently, or NHS 111 in the UK, if any of these apply (NHS, 2023):

• You cannot eat or drink.
• You have pain around your jaw, ear or at the side of your head.
• You have difficulty opening your mouth fully, or your jaw is locking.
• You have frequent, severe headaches.
• You have pain or tenderness at the side of your head or on your scalp.
• You have vision problems, such as double vision or loss of vision in one or both eyes.

For a guard that hurts or a bite that feels different, your dentist is the right first stop, even if nothing is painful. The NHS also advises seeing a dentist if you grind and have pain in your jaw, face or ear (NHS, 2026).

Your guard should make things easier

A night guard has to fit you, and follow-ups exist for that reason. Try the bite check tomorrow morning.

TMJ symptoms often settle with time and conservative care, as our article on how long TMJ lasts explains, and our TMJ disorder guide covers causes and treatment.