To answer correctly the question of what is a canker sore means investigating an individual's oral health condition as well as his or her immune system. Medically referred to as an aphthous ulcer, a canker sore is a painful mouth ulcer affecting the inner cheek, inside the lower lip, roof of the mouth or upper throat area.

An emerging canker sore is normally preceded by a burning, tingling sensation that eventually develops into a bump felt by the tongue. When first seen, the ulcer is just a red spot but quickly breaks open to become a mouth ulcer. The grayish area surrounded by a red circle is created from fibrin layers, an important blood-clotting protein. Sometimes during a canker sore episode, a person may experience swelled lymph nodes that are also sore to the touch, in addition to low-grade fever and extreme sensitivity to hot, spicy or abrasive foods.

Lesion diameter determines how canker sores are classified. For example, canker sores deemed as “minor" ulcerations are tiny, less then 0.4 inches in size, and represent the most common of all canker sores. They are characterized by a grayish-yellow interior that is surrounded by a pale red halo. Ulcers that are particularly white in color cause severe pain and may produce lip swelling if the ulcer is near the mouth. Minor ulcerations can last up to two weeks and eventually disappear without treatment.

Aphthous ulcers that are larger than ten millimeters in diameter are diagnosed as "major" ulcerations. Taking more than several weeks to heal, these ulcers frequently affect young adults and may cause scarring on the cheeks, tongue or lips.

The most severe kind of canker sore is the herpetiform ulceration. Women seem to be affected by this type of lesion more than men, especially women in their 20s. Lesions are small but form large clusters that are difficult to treat although, unlike major ulcerations, herpetiform ulcerations usually do not cause scarring.

Sores occur when the mucus membrane breaks open due to inflammation that doctors suspect may emerge when the immune system is compromised by infection or trauma. However, other reasons for the development of canker sores are also included in the list of suspect agents, such as:

• Eating too much fried or spicy foods
• Experiencing chronic stress and fatigue from overwork or other life issues
• Food allergies (especially cow's milk)
• Extreme or sudden weight loss
• Viral infections
• Deficiencies in folic acid, vitamin B12, zinc and iron
• Suffering from Crohn's disease
• Brushing hard enough to produce scrapes on the gums and other oral tissues
• Accidentally biting the inside of the mouth

How Sodium Lauryl Sulfate Contributes to Canker Sores

Commonly known as "SLS", the surfactant sodium lauryl sulfate is derived from palm oils and is added to many hygiene and cleaning products such as laundry soap primarily as a foaming agent. Excellent for removing stains, oil and grease from a variety of surfaces, SLS is also an ingredient of many toothpaste brands because of its ability to produce a visible aeration while a person is brushing. Marketing experts think that this "foaming" action makes consumers think the product is really working the way it should.

However, several clinical trials involving SLS have linked the subsequent development of canker sores in people who brush regularly with toothpaste containing sodium lauryl sulfate. Scientists think this is because SLS denatures the layer of mucosal mucin protecting the oral epithelium, exposing it to abrasive agents or allergens that facilitate the evolution of cankers sores. According to reviews of the literature regarding the correlation between SLS and mouth lesions, people using oral products containing SLS experience an increased amount of epithelial desquamation leading to significantly more incidences of canker sores.

Dr. Katz Discusses SLS in Toothpaste and Canker Sores

Are There Any Toothpastes Without Sodium Lauryl Sulfate?

The majority of major brand toothpastes do contain SLS, although the manufacturers claim that SLS does not harm the mouth and actually helps clean teeth. However, with many substantiated tests published in various academic journals supporting the association between sodium lauryl sulfate and canker sores, consumers should be wary of this claim by corporations sponsoring toothpastes and mouthwashes made with SLS.

Fortunately, Dr.Katz's line of TheraBreath products that include toothpastes, mouthwashes and gargles do not contain sodium lauryl sulfate. Nor do any of his products contain alcohol, benzalkonium chloride or saccharin, all of which are ineffective, non-essential and potentially harmful ingredients found in many over the counter oral hygiene products.

In addition to reducing the appearance of canker sores, TheraBreath toothpaste and oral rinse contain an exclusive ingredient developed by Dr. Katz called OXYD-8, a stabilized form of chlorine dioxide that eliminates oral bacteria responsible for halitosis, periodontal disease and dry mouth syndrome. While researchers do not think that bacteria contributes to canker sore development, many people suffering from chronic mouth lesions may also have dry mouth and/or bad breath.

What is a Canker Sore when it Fails to Heal?

If a canker sore does not disappear after several weeks and persists without change, doctors may perform certain tests to determine whether it is indeed a canker sore. Although canker sores are not cancerous, they do resemble a type of mouth ulcer called squamous cell carcinoma, which can be distinguished from ordinary mouth lesions using a biopsy procedure. Additionally, returning canker sores could be produced by drug allergies, a skin disorder called erythema multiforme that occurs due to allergic infections and bullous lichen planus, a somewhat rare disease affecting the tongue, skin and mouth.

Relieving the Pain of Canker Sores

Canker sores are painful, disrupting normal everyday activities like eating, drinking and talking. While waiting for the lesion to heal, people suffering from them may apply analgesic gels to the sore that temporarily alleviates the pain. Taking extra vitamin C, B and/or zinc may also expedite the healing process, especially if a lack of these nutrients played a role in creating the canker sore. Covering the lesion with a baking soda paste and then placing a piece of ice over the sore will help lessen pain as well.