Commonly termed canker sores, aphthous ulcers, or aphthous stomatitis, have been the focus of study and research for many years, although the exact etiology of the lesions has yet to be identified. Categorized as an idiopathic disease, aphthous ulcers are frequently misdiagnosed, treated incorrectly, or simply ignored.

Recurrent aphthous ulcer (RAU), or recurrent aphthous stomatitis (RAS), represents a chronic inflammatory disease characterized by painful oral ulcers recurring with varying frequency. Examples of aphthous ulcers are shown in the images below.

Recurrent aphthae in floor of mouth, showing ovoid ulcer with inflammatory halo.

Typical aphthous ulcer in a common site, showing inflammatory halo surrounding a yellowish, round ulcer.

Children with recurrent aphthous ulcers (canker sores) may reduce their oral food and fluid intake because of the associated pain and subsequently become dehydrated; therefore, aggressive therapy for the lesions can be important.

Recurrent aphthous ulcers (canker sores) may initially appear as erythematous, indurated papules that erode to form sharply circumscribed necrotic ulcers with a gray, fibrinous exudate and an erythematous halo. The 3 categories of recurrent aphthous ulcers (canker sores) are as follows:

• Minor aphthous ulcers (80-85% of recurrent aphthous ulcers [canker sores]) are 1-10 mm in diameter and heal spontaneously in 7-10 days.
• Major aphthous ulcers (also called Sutton disease) constitute 10-15% of recurrent aphthous ulcers (canker sores). These lesions are greater than 10 mm in diameter, take 10-30 days or more to heal, and may leave scars.
• Herpetiform ulcers (5-10% of recurrent aphthous ulcers [canker sores]) are multiple, clustered, 1-mm to 3-mm lesions that may coalesce into plaques. These usually heal in 7-10 days.

Treatment

Few patients are unresponsive to the local or systemic therapies described above; however, several other invasive and specialized treatments are available for patients with persistent or severe lesions.

• Laser therapy is perhaps one of the most intriguing treatments. Studies have shown that laser therapy of most aphthae immediately relieves pain, speeds healing, and reduces recurrences. ^{[54, 55, 56, 57]} Limitations include impracticality of the treatment. Lasers are expensive, and specialized training is required to operate them. Patients who have severe disease or frequent recurrences may benefit from referral to a laser treatment center or specialist.
• Controversy continues to surround the application of silver nitrate. This therapy promotes changing the lesion to a burn. Some studies revealed decreased severity of pain; ^[58] however, none have demonstrated shortened healing time. Additional and large studies are needed before this therapy can be recommended on a routine basis.
• One of the more controversial therapies involves removing biopsy specimens from lesions as a therapeutic modality. When biopsy is performed, the lesion is changed from an immune-mediated lesion to a traumatic lesion. Some believe that these traumatic lesions are less painful and heal faster than typical aphthous ulcers. Limited data support this practice, and it cannot be recommended.

Written by Michael C Plewa, MD