After biting the inside of your cheek: caring for the traumatic ulcer and why it keeps happening

When you bite the inside of your cheek during a meal or while talking, the spot swells and turns white and raw with a stinging sore, a traumatic ulcer. In Korea, the National Health Information Portal names trauma as one of the causes of non-infectious stomatitis, and Seoul National University Hospital's medical information explains that biting the cheek can cause oral mucosal disease. It usually heals on its own once the cause is gone, but if the same spot is bitten repeatedly or the sore lasts long, the state of the teeth and prostheses should be checked.

Published 2026-11-08 · Updated 2026-11-08 · DentalStatics editorial team

Key facts

Classification of stomatitis	Trauma is one of the causes of non-infectious stomatitis (source: KDCA National Health Information Portal)
Prevention rules	Do not chew while talking; use wax on sharp parts of orthodontic or dental appliances (source: Seoul National University Hospital)
Relation to aphthae	Injuries to the cheek and tongue are aggravating factors of aphthous stomatitis (source: Seoul National University Hospital)
Signs of clenching	Tooth marks on the cheek lining or tongue are checked in the simple jaw joint exam (source: KDCA National Health Information Portal)
Long-lasting ulcer	An ulcer that does not heal in about 3 weeks is a subject for biopsy (source: National Cancer Information Center, National Cancer Center)

Why does the cheek turn white and raw when bitten?

The lining on the inside of the cheek is thin and soft, so once it is bitten hard by the teeth the surface peels and swells. After a day or two a white or yellowish film covers the wound, a look commonly seen as a wound heals.

The swollen spot juts further between the upper and lower teeth, so it is easy to bite the same spot again. When this repeats, the wound gets bigger and takes longer to heal, so for the first few days after biting it is good to chew less on that side and to cut food small and eat slowly.

A wound from cheek biting can also be a trigger of aphthous stomatitis. Seoul National University Hospital's medical information names injuries to the cheek and tongue, and mucosal damage from brushing or eating, as aggravating factors and local causes of aphthous stomatitis.

Why do I keep biting my cheek?

Biting once or twice is common, but if the same spot keeps getting bitten you should look for the cause. If the cause is left as it is, the wound repeats with no time to heal, so have the dentist check whether any of the items below apply.

The habit of clenching the teeth is also a habit that the National Health Information Portal names as a behavioral contributing factor to TMD. If you are putting enough force to leave marks on the inside of the cheek, also check whether you have jaw pain or morning jaw stiffness.

A tooth that is chipped or worn to a point
A prosthesis with a rough edge or a height that does not match
Wires or brackets of an orthodontic appliance
A wisdom tooth that grew tilted toward the cheek
A habit of clenching the teeth in the daytime or of biting the inside of the cheek
The habit of chewing food while talking

How do I care for a wound from cheek biting?

Most heal on their own once the cause is gone. While the wound is there, avoid foods that irritate it, such as spicy and salty foods and hard, sharp snacks, and after meals rinse the mouth with water so no food is left.

For preventing stomatitis, Seoul National University Hospital's medical information advises not chewing while talking and using wax on sharp parts of orthodontic or dental appliances. If an orthodontic appliance keeps scratching the cheek, cover it with wax and ask for an adjustment at the next orthodontic visit. If the pain is severe, you can get a medicine that protects the wound prescribed at the dentist.

Until the wound heals, cut back on the habit of touching it with your tongue or fingers, which can slow recovery. Keeping the mouth clean is the basis, so even if it hurts, keep brushing with a soft toothbrush.

Are white lines or marks on the inside of the cheek from biting too?

A fine white line or tooth-shaped marks along the height where the teeth touch the inside of the cheek may be related to a clenching habit. The National Health Information Portal explains that tooth marks imprinted on the cheek lining or tongue are checked in the simple jaw joint exam.

However, if white lines spread in a net-like pattern or the area is red, raw and stinging, it may be oral lichen planus. Seoul National University Hospital's medical information explains that lichen planus appears as white lines in a net-like pattern, or as lining that is red, thinned and raw. A white patch that does not rub off must also be told apart from leukoplakia, which the National Cancer Information Center explains can be a precancerous lesion, so have a white lesion that you do not remember biting checked at the dentist.

What should I do if a bite wound does not heal?

According to the National Cancer Information Center of the National Cancer Center, ordinary inflammation heals in 2 to 3 weeks, so an ulcer still there after about 3 weeks is hard to regard as simple inflammation and becomes a subject for biopsy. Even for a wound you clearly remember biting, get an exam if it goes past this period.

A wound also lasts long when the same spot is bitten continually and has no time to heal. If an ulcer remains even after a sharp tooth is smoothed or an ill-fitting prosthesis is fixed, a biopsy is considered to rule out other causes.

Common myths and facts

Myth: White lines inside the cheek are all bite marks and not worth worrying about.

Seoul National University Hospital's medical information explains that oral lichen planus can appear as net-like white lines, and the National Cancer Information Center describes a white lesion that cannot be wiped off as leukoplakia, which can be a precancerous lesion.

Myth: A bite wound will eventually heal no matter how long it lasts.

By the National Cancer Information Center's guidance, an ulcer that has not healed in about 3 weeks is a subject for biopsy. Even if you think the cause is trauma, it needs to be checked once the period is exceeded.

Frequently asked questions

Can I put mouth sore ointment on a cheek bite wound?

A traumatic wound mostly heals on its own once the cause is gone. If the pain is severe, the dentist can prescribe a medicine that protects the wound. Some ointments do not suit infectious stomatitis, so if the wound looks different from your usual mouth sore, get an exam first.

I keep biting the same spot. Do I need to have my teeth smoothed?

If the same spot is bitten repeatedly, have the dentist check whether a sharp tooth tip or the edge of a prosthesis is the cause. If the cause is clear, it is sometimes solved by treatment such as smoothing the surface or adjusting the prosthesis. If the cheek began to be bitten after a new prosthesis was made, be sure to say so.

I seem to bite my cheek in my sleep. Why?

If the inside of the cheek is raw in the morning or tooth marks are left deeply, you may have clenched your teeth during sleep. If grinding or clenching is suspected, the dentist checks tooth wear and the state of the jaw muscles together and, if needed, discusses a device to wear at night. If the marks inside the cheek deepen every morning, taking a photo and showing it at the visit is also an option.

My cheek got sore from my orthodontic appliance. What should I do?

Seoul National University Hospital's medical information advises using wax on sharp parts of orthodontic or dental appliances. Wounds form easily right after an appliance is first attached or adjusted, so cover it with wax, and if a wire end keeps poking, contact the orthodontist for an adjustment.

By when should I get care if a bite wound doesn't heal?

Even for a bite wound, get care if it has not healed by about 3 weeks. That is the very point at which the National Cancer Information Center recommends a biopsy. Even before that, get an exam early if the wound keeps growing, feels firm, or appeared with no memory of biting.

References

Korean version →