What Is a Canker Sore?
"Stomatitis" is the inflammation of the oral mucous membranes. In aphthous stomatitis, the inflammation of oral mucous membranes is recurring and painful. The lesions present as painful large or small ulcers ranging from 1 mm (small canker or aphthous sore) to 2 cms (large canker or aphthous sore). The uncommon clinical feature of this oral condition is not only the ulcerations are pinpointed and varied, but also they are rather reddish like a macule and less like a papule. They do not appear like blisters, but the ulcers have a characteristic erythematous reddish flare with a yellowish-white central covering (called the "pyogenic membrane"). These single or multiple variated ulcers are usually round to oval in shape, and in the region like the oral vestibule, the lesions often appear elongated or stretched.
What Are the Causes of Aphthous Stomatitis?
Not only are canker sores quite common in many patients, but also they represent the most frequently occurring oral lesions in almost 20-60% of the general population. Though all age groups are affected alike, its prevalence is more in the female and young adult populations. If the canker sores are recurrent in nature (as they usually are) and if left untreated, it takes the shape of a continuous pathologic entity or disease process for many years and eventually causes severe pain and large ulcerated bases in the oral cavity.
Canker sores can also be a sign of some serious underlying systemic disease or syndrome, as in the case of Crohn's disease (inflammatory bowel disease), Behcet's syndrome, systemic lupus erythematosus, or inflammatory reactive forms of arthritis. In certain malabsorption syndrome, vitamin deficiencies (vitamin B6, B12), and hematinic iron and folate deficiencies, canker sores or aphthous ulcers are commonly found. Also, in patients with poor or compromised oral hygiene and in smokers alike, the microbiome of the oral cavity that constitutes the oral epithelial defense is severely impacted. Hence in these cases as well, canker sores are a common finding.
What Is the Pathogenesis of Aphthous Stomatitis?
Though idiopathic and related to not a single or any specific cause (multifactorial origin), canker sores tend to be noninfectious and localized in the oral mucous membranes. They can be triggered not just by stress and lifestyle disease but can be a result of local irritations, sensitivity, allergies, trauma, excess toxin exposure (like nitrate exposure), or even hormonal fluctuations (like in menstrual cycles).
The pathogenesis of canker sores lies in the T cell-mediated immunity that is dysfunctional because the oral epithelium at the site of ulceration is destroyed or destructed partially because of neutrophils, mast cells, and cell mediators that are responsible for maintaining oral epithelium integrity (like interferon-alpha, TNF (tumor necrosis factor) alpha, interleukins or IL 1, 2 and 5). This destruction or partial destruction when the epithelial immunity of the oral mucosa is breached creates the pseudomembranous manifestation acquired in aphthous ulcerations.
The common misconception the dental surgeon needs to avoid while often diagnosing aphthous ulcers or canker sores is from herpetic ulcers. When several large aphthous ulcers or canker sores form a large irregularly-shaped ulcer with a huge common or central base, it is referred to as a herpetiform pattern ulcer which is a subtype of aphthous stomatitis but is not caused by the herpes virus. Herpetiform ulcerations are less prevalent compared to minor and major aphthous ulcers and heal in a few week's time eventually.
Site of Pathology:
The following sites of the oral cavity are the most affected by aphthous ulcerations:
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Marginal or unattached gingiva of the teeth.
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Non keratinized oral mucosa or labial and buccal surfaces over the teeth.
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Ventral surface of the tongue.
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The lateral surface of the tongue.
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Tonsillar fauces.
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Soft palate.
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The floor of the mouth.
What Are the Clinical Manifestations of Aphthous Stomatitis?
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On local dental examination or routine dental checkup, the ulcers appear round or oval with a pseudomembranous appearance with a gray exudate.
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The erythematous halo is characteristic of these lesions on the non keratinized part of the oral mucous membranes.
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The patient may complain of a burning sensation in the mouth (prior to the onset of ulceration) or pain and discomfort while swallowing and chewing food.
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Fever or febrility is an uncommon feature of patients having canker sores. The patient will be afebrile, reporting only mild or moderate local irritation in the ulcerated area.
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Similarly, rashes, headaches, and lymphadenopathy are also uncommon.
How Are Aphthous Stomatitis Diagnosed?
The patient's medical history should be taken regarding the past occurrence of ulcerations, periodic fever, or dehydration, as this would be suggestive in the differential diagnosis with other conditions like herpangina or Behcet's syndrome.
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In case of hematinic or specific vitamin deficiencies, if neutropenia (abnormal reduction of the neutrophils - the main type of white blood cells in the body) is observed in the complete blood count, then the diagnosis would be aphthous ulcerations due to cyclic neutropenia.
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In less than 5% of the cases with aphthous ulceration, underlying celiac disease or gluten-enteropathy is often possible. In such cases, a transglutaminase assay has to be performed to confirm the underlying disease.
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The dental surgeon should also carefully observe if the recurrent or herpetiform ulceration has involved the hard palate or the dorsal surface of the tongue or any keratinized part of oral mucosa would indicate an underlying HIV infection that needs to be confirmed by HIV test.
How Are Aphthous Stomatitis Managed?
Minor aphthous ulcers are self-healing within 1 to 2 weeks, but recurrently minor and major aphthous ulcers may take months to heal, often with the pronounced impact of scarring on the oral mucosal tissues.
The first line of treatment in small ulcerations is to always prescribe a topical anti-inflammatory and antiseptic gel for application to the affected area that contains an anesthetic component (Benzocaine or lidocaine), antiseptic component (Triamcinolone or Dexamethasone), anti-inflammatory component (chlorhexidine gluconate, hydrogen peroxide).
Withdrawal of certain foods like gluten and tomato and discontinuing toothpaste with sodium lauryl sulfate has also proved effective in some cases. In severe cases, systemic administration of Prednisone or local steroid injection with Triamcinolone can be effective in preventing severity and recurrence. Similarly, for long-term therapeutic purposes, laser therapy and dietary vitamin supplementation will reduce the recurrence rates of canker sores.
Conclusion:
To conclude, good oral hygiene, regular dental checkups for diagnosing oral ulcerations are effective in the prevention of aphthous ulcers or canker sores. Often they indicate a systemic component that needs to be diagnosed by the physician and cross-checked for differential diagnosis by the dental surgeon to appropriately treat the inflammatory ulceration in the oral mucous membranes.
