Gingivitis vs Canker Sore: How to Tell Them Apart

A single sore spot on your gum usually is not the same thing as gingivitis.

Gingivitis affects the gum line around teeth, while a canker sore is a small ulcer on the soft tissue. If the spot is not healing or you are unsure what you are seeing, a dentist should look at it.

Gingivitis affects the gum line, not just one spot

Gingivitis is inflammation of the gums around the teeth. The gums often look red, puffy, or shiny, and they may bleed when you brush or floss.

A sore area from gingivitis usually follows the gum line or sits around several teeth. It is not usually a single round ulcer with a white or yellow center.

• Choose gingivitis if the gums bleed easily, look swollen, or feel tender along the tooth edge.
• Choose a canker sore if there is one distinct ulcer on soft tissue, away from the full gum line.

Most people walking around with gingivitis aren’t told by their providers that they have gingivitis. We say things like “puffy gums” “deep prone depths” “lots of inflammation” “inflamed gums” “bleeding gums “ “easy bleeding” and “bleeding on probing” without explaining that there is a diagnosis of gingivitis or periodontitis.

— r/askdentists

A canker sore is usually one painful ulcer

A canker sore is a small open sore inside the mouth. It often has a white, gray, or yellow center with a red rim, and it can sting when you eat, brush, or touch it.

Canker sores do not usually cause the whole gum margin to look inflamed. They are more likely to show up as one isolated spot on the inside of the lip, cheek, tongue, or sometimes the gum tissue.

Aw man…. I always go through the wax the ortho gives me super quickly because of my regular canker sores. I’ll ask for extra during my next visit

— r/askdentists

A sore on the gums is not always gingivitis

A sore on the gums can come from irritation, a canker sore, a sharp tooth edge, or a cleaning injury. Gingivitis is different because it changes the appearance and behavior of the gums around more than one point.

If the sore is only in one place and the rest of the gums look normal, that pattern leans away from generalized gum inflammation.

What does gingivitis look like in a photo

Gingivitis often looks like a red or darker band along the gum line. The gums may look puffy, bleed with light contact, and sit less snugly around the teeth than usual.

People often miss gingivitis when they look only for pain. The gums can be inflamed before they feel very sore, so bleeding and swelling matter more than pain alone.

They bleed because they are inflamed; you have a level of gum disease called gingivitis. The good news is that with diligent care, this can be reversed. You just need to brush and floss your teeth regularly.

— r/askdentists

A gum ulcer that is not healing needs a check

An ulcer on the gum that lasts longer than about two weeks should be checked by a dentist or doctor. A sore that grows, keeps reopening, or comes with fever, swelling, or trouble swallowing needs faster attention.

A lingering sore is not something to guess at from photos alone. A clinician can tell whether it is a canker sore, an irritation spot, or something else that needs treatment.

The first step is to match the pattern, not the pain

The best clue is whether you have one isolated ulcer or a broader pattern of gum inflammation. One sore spot points more toward a mouth ulcer, while red bleeding gums around teeth point more toward gingivitis.

If the area is painful and you are unsure, stop picking at it, brush gently, and book an exam if it does not improve soon. That is the safest way to sort out gum disease or mouth ulcer when a photo is not enough.

It’s really just a hygiene issue. She’s probably missing those spots repeatedly. You can’t get buildup and gingivitis like that red spot with good hygiene. Make sure she is flossing, and google the bass method of brushing. Brushing should include tooth structure AND the gum line.

— r/askdentists

Common questions

What is the difference between gingivitis and a canker sore?

Gingivitis is gum inflammation along the tooth edge, while a canker sore is a single ulcer on soft tissue. Gingivitis tends to cause bleeding, puffiness, and redness across a gum area, not just one round sore.

How do I tell a sore on the gums from gingivitis?

A sore on the gums is usually one painful spot with a clear center or an obvious irritation point. Gingivitis usually makes the gums around teeth look red, swollen, and easy to bleed.

What does gingivitis look like?

Gingivitis often looks like red, puffy, or shiny gums that bleed with brushing or flossing. The change is usually along the gum line rather than in one isolated ulcer.

Why is there an ulcer on my gum that is not healing?

A gum ulcer that is not healing can be a persistent canker sore, an irritation from a sharp edge, or something that needs an exam. If it lasts more than about two weeks, get it checked by a dentist or doctor.

Start by looking at the shape of the problem. One isolated ulcer points one way, while red bleeding gums around teeth point another.

If you still cannot tell, take a clear photo for yourself, avoid irritating the spot, and book a dental visit if it is not improving or if the soreness is getting worse.