Mouth Sores: What They Are and How To Treat Them

Phoenix Dentist Mouth sores (also called mouth ulcers) can be annoying and painful, but are they serious enough to have your dentist treat them?

“Persistent mouth ulcers always are a sign you should call your dentist,” says Dr. Carol Ford from her Phoenix dental office. “They can be harmless, but they can also be a sign of oral disease, and your dentist will know the difference,” she adds.

The American Dental Association notes that the most common cause of mouth sores are

  • Infections from bacteria, viruses or fungus
  • Irritation from a loose orthodontic wire, a denture that doesn’t fit, or a sharp edge from a broken tooth or filling
  • the symptom of a disease or disorder

Because it is difficult for a patient to know which of these is the cause of a recurring mouth sore, it’s best to make an appointment to see your dentist.

There are three common mouth sores you may experience:

Canker Sores

The ADA says that the most common type of sore is a canker sore (or aphthous ulcer). They are painful, greyish bumps with bright red edges. They are not contagious, and they will last a week to 10 days. The cause is unknown, but most dentists think canker sores are caused by an immune imbalance or a bacterial or viral infection.

“Antimicrobial mouthwashes may help relieve the pain, as well as over-the-counter soothing or anesthetic creams or gels,” says Dr. Ford.

Fever Blisters (Cold Sores)

These small, fluid-filled blisters erupt around the edges of the mouth or nose, and sometimes the chin. They are highly contagious and may be painful. When they first erupt, they may itch, and before they heal they will scab over. Fever blisters are caused by the herpes simplex virus and the initial outbreak may feel like the flu or a bad cold. Once the initial infection goes away, the virus remains in the body and causes new outbreaks.

“If the outbreaks are frequent or severe, your dentist can prescribe anti-viral medication and some topical treatments that ease the itching or pain,” says Dr. Ford.


Patches of white fuzzy material indicate a fungal infection called moniliasis or oral thrush. Caused by the overgrowth of the yeast candida albicans, this infection is often found in denture wearers. It can also be passed from a nursing mother to her baby. It is most common among those with weak immune systems, the very young or the elderly. Thrush is also common in people with diabetes or leukemia. People with dry mouth syndrome are also susceptible to candidiasis.

“Thrush can often go away if the underlying problem—like dry mouth—is relieved,” says Dr. Ford. “There are also anti-fungal prescription medications to resolve the yeast overgrowth,” she adds.

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