How to identify canker sores. / How to distinguish canker sores from other types of mouth ulcers.

Identifying canker sores. / How can you tell a canker sore from other types of mouth ulcers?

Dentists distinguish canker sores from other types of mouth ulcers by way of: 1) Taking a history from their patient. 2) Evaluating the symptoms they have experienced. 3) Visual inspection.

The hallmark characteristics of canker sores are their appearance (pictures), location, and the fact that they are recurrent. Typically there is no medical testing (i.e., biopsy or culturing) that is used to diagnose canker sores.

Distinct from the appearance of the lesion itself, the tissues surrounding a canker sore will appear healthy and the patient will have no distinguishing systemic features (such as a fever or malaise).

Where do canker sores form?

Canker sores (typically) only form on the "loose" tissues of the mouth (those areas where the skin is not tightly bound to the underlying bone).

These types of tissues include the skin covering the inside of the lips and cheeks, the floor of the mouth, the tip or underside of the tongue, the soft palate, and the tonsillar areas. Dentists refer to the skin in these areas as the "nonkeratinized" tissues of the mouth.

[ While rare, it is possible for canker sores to form on the topside of the tongue or on keratinized tissues (such as the gum tissue that surrounds a person's teeth). ]

What do canker sore mouth ulcers look like?

A canker sore's earliest stage will be characterized by the formation of a raised, erythematous (reddened) area on the skin in one of the locations described above. Often this elevation will be associated with a burning or tingling sensation.

This initial reddened lesion will subsequently degenerate into an ulcer taking the following classic form:

• A shallow individual ulcer that is round or oval in shape.
• The ulcer will usually be no more than a 1/4 inch in diameter.
• The center of the ulcer will be covered with a loosely attached white or grayish membrane.
• The edges of the ulcer will be regular (not jagged) and surrounded by a reddish halo. The tissue adjacent to the canker sore will be healthy in appearance.
• Canker sores usually are painful. It is common that the presence of a canker sore will interfere with eating or will cause a person to want to limit their oral movements.

Canker sore healing.

• Canker sores can be expected to heal within 4 to 14 days. In most cases this healing is uneventful and results in no residual scarring.
• Any mouth ulcer that has not healed within a 2 week time frame should be evaluated by a dentist.
• Another type of aphthous ulcer (Major aphthae) do characteristically have an extended healing time frame.

Canker sore outbreak frequency.

• Once a person has initially experienced an outbreak of canker sores the probability of recurrence is high, although the rate of recurrence is quite variable. A rate of one outbreak every 1 to 3 months would be considered typical (encompassing 50% of those who get canker sores). 30% of people who suffer from outbreaks of these lesions deal with their presence on a monthly basis.
• It's been estimated that roughly 20% of the general population experiences canker sores.
• A person's first encounter with canker sores will typically take place between the ages of 10 and 20 years and then decrease in frequency and severity as the person ages.
• Canker sores are most prevalent in people 10 to 40 years of age.
• Some studies have suggested that women are more likely to experience canker sores than men (but not all studies have confirmed this fact).
• The potential to experience canker sores appears to be unrelated to race. The occurrence of these lesions does seem to be more common in people who live in North America as opposed to those who live on other continents. There is a greater prevalence for canker sores in non-smokers and people in upper socioeconomic groups.

Can a person have more than one canker sore at a time?

• Outbreaks of multiple canker sores can and do occur (in contrast to the classic single ulcer form). Usually the total number of canker sores that will form at one time will be six or fewer. If multiple canker sores do develop they tend to be widely distributed throughout the person's mouth (as opposed to being clustered together).
• If two canker sores exist in close proximity to each other they may coalesce into a single larger and irregularly shaped mouth ulcer (as opposed to the classic round or oval shaped lesion).
• The number of outbreaks of canker sores a person experiences can vary greatly. Most persons will have only a few episodes a year while, at the other extreme, others will have nearly continuous outbreaks and will never be free of mouth ulcers for an extended period of time.
• Canker sores are smallish shallow mouth ulcers. There is another form of aphthous ulcer that is more severe in nature. These lesions are termed "major aphthae" or "Sutton's ulcers." We describe them in greater detail below.

Are canker sores contagious?

• There is no evidence to suggest that canker sores are contagious.

What are "major aphthous ulcers"?

Major aphthae (also termed "Sutton's Ulcers") are a type of aphthous ulcer characterized by a large deep ulceration. The healing of these lesions is typically slower and more painful than that associated with canker sores. Their presence may cause regional, or even facial, swelling.

Unlike canker sores, major aphthae form on all types of oral mucosa (both keratinized and nonkeratinized tissues). They often approach 1/2 inch (or more) in diameter. Their healing typically takes between 10 and 40 days. In some cases, however, it can take months (even as new ulcers are forming). Healing is often associated with scarring.