Why does my night guard leave a sore or ulcer?

A night guard can irritate your gums, cheek or tongue when one area presses or rubs the same spot. The tissue may look red or raw, or it may develop an open sore. A poor fit, rough edge or movement during sleep may be the reason. 

What you will learn: 

• Night guard sores usually come from repeated pressure, rubbing or a rough or uneven fit. 

• Store-bought and custom guards can both cause irritation if they do not fit properly. 

• Stop wearing a guard that keeps touching a sore until the fit can be checked, and use gentle care while the area heals. 

• A sore that lasts more than two weeks, keeps returning, bleeds, feels numb or gets worse should be examined by a dental provider. 

If your night guard keeps causing sore spots, schedule an appointment with an Aspen Dental provider. Your care team can check the fit and find out what's wearing on your mouth. 

What causes a sore spot from a night guard? 

A night guard may create a sore if it keeps pressing or rubbing the same area. A loose guard may slide, while a tight or bulky guard may pinch the tissue. A rough edge or seam may also scrape your gums, cheek or tongue. 

Repeated contact can leave the tissue red or raw and may lead to an open sore. A dental provider can check the fit and find the part of the guard that is causing the irritation. 

Is a store-bought guard more likely to cause sores? 

Not always. The main concern is how the guard fits, not whether it came from a store or a dental office. 

A boil-and-bite guard is shaped at home, so it may rub if it feels bulky, loose or uneven. A custom guard can also need an adjustment. Stop using any guard that hurts or keeps scraping the same spot, and bring it to your dental provider. Learn what to consider before using a drugstore night guard. 

Is it a canker sore, an ulcer or something else? 

A sore where the guard rubs may be an injury to the lining of your mouth. However, an injury inside the mouth can also bring on a canker sore, so the two problems may look similar. 

MedlinePlus describes a canker sore as a painful open spot with a white or yellow center and red around it. Healing may take one to three weeks. A sore that gets worse or comes with a fever should be checked.¹ 

A dental provider can help tell the difference, especially if the sore keeps returning. You can also learn more about common mouth ulcers.

What can help while the sore heals? 

If the guard keeps touching the sore, stop wearing it until your dental provider checks the fit. If the guard was prescribed for a specific medical reason, ask your dental provider how long it is safe to leave it out. 

Until then, gentle care may help keep the area comfortable. The following steps are also recommended for canker sores.¹ 

• Rinse your mouth gently with salt water. 

• Avoid hot or spicy foods that make the area sting. 

• If you use mouthwash, choose a mild one without alcohol. 

• An over-the-counter numbing rinse or drop may provide brief relief. Follow the label. 

These steps may ease the discomfort, but they will not correct a poor fit. A dental provider may be able to smooth the rough area, adjust the guard or recommend a replacement. 

When should you see your dental provider about a night guard sore? 

The National Institute of Dental and Craniofacial Research advises getting care when a mouth sore or irritation lasts longer than two weeks. It also lists bleeding, numbness and trouble chewing or swallowing as reasons to be examined.² 

These signs do not tell you what is causing the sore, but they do mean that a dental provider should look at it. Get help sooner if the area is quickly getting worse or the swelling is severe. 

Your dental provider can examine both the sore and the guard. The guard may need to be adjusted, smoothed or replaced. Your dental provider can also decide whether the sore needs further testing. 

Don't wait out a night guard sore that keeps coming back. Contact your local dental provider to have the fit checked, get the guard adjusted and get back to sleeping without pain. 

Why does my night guard leave a sore or ulcer? FAQs 

Still have questions about night guard sores? These answers cover a few common concerns. 

Should I wear my night guard while the sore heals? 

If the guard touches the sore or makes it hurt more, leave it out until your dental provider checks the fit. If you were told to wear the guard for a specific medical reason, call your dental provider before taking a longer break. 

Is it normal for a new night guard to cause some soreness at first? 

Mild soreness for the first few nights can be normal as your mouth adjusts to a new guard. This is different from a sore that keeps returning in the same spot or gets worse over time. If the discomfort doesn't ease up after a few nights, or if you notice an open sore, have your dental provider check the fit. 

Could I be allergic to the guard? 

The American Academy of Oral Medicine notes that resins and acrylics are among the dental materials associated with oral contact allergy. Possible signs include redness, swelling, peeling or an ulcer. These changes can have other causes, so a dental provider may need to examine the area and decide whether testing is useful.³ 

Can I file down the guard myself? 

No. Filing or trimming the guard may change its fit or create another rough edge. Let your dental provider make the adjustment. 

Should I switch to a custom guard? 

A custom guard may help if your current guard does not fit well, but it is not a guarantee against sore spots. Your dental provider can check whether your guard should be adjusted or replaced. 

Sources 

¹ National Library of Medicine, MedlinePlus Medical Encyclopedia: “Canker sore.” https://medlineplus.gov/ency/article/000998.htm 

² National Institute of Dental and Craniofacial Research: “Oral Cancer.” https://www.nidcr.nih.gov/health-info/oral-cancer 

³ American Academy of Oral Medicine: “Oral Contact Allergy.” https://www.aaom.com/clinical-practice-statements-oral-contact-allergy