Canker Sores
Canker sores, also known as recurrent aphthous stomatitis (RAS) or recurrent aphthous ulcers (RAU), are one of the most common oral ulcer conditions, affecting up to 66% of the population at some point in their lifetime.[1,2] About 1% of children from higher socioeconomic backgrounds in developed countries are affected by canker sores.[1] RAS usually occurs in an otherwise healthy individual.
The key distinguishing presentation of RAS is that it appears on movable oral mucosa as opposed to keratinized, nonmovable tissue. Slightly more females than males experience RAS.[3] The rate of recurrence of RAS is up to 25%, with a 3-month recurrence rate as high as 50%.[4] Most people develop one to three ulcers at a time and may have a recurrence from immediately after an old ulcer heals to up to twice a year.
Clinical Presentation
Diagnosis of RAS is based on history and clinical appearance of the lesions. Canker sores usually first appear in the mouth as single or multiple small, red, round or ovoid spots with a prodromal symptom of tingling or burning that can occur 1 to 2 days before the appearance of the ulcer. Then an ulcer appears that is clearly defined, shallow, round, or oval with a red halo and a yellowish-gray center. Pain usually dissipates after 3 to 4 days and the lesion turns gray, at which point epithelialization occurs.[1,4] RAS ulcers are extremely painful and may interfere with talking and eating.
There are three classifications of RAS, which are differentiated according to the size of the lesion:[2,4,5]
Minor RAS, the most common type, appears as small ulcers of 5 to 10 mm. Healing occurs in about 7 to 10 days. Minor RAS is frequently seen on the floor of the mouth, inside of the cheek, and on the ventral and lateral board of the tongue. There is no residual scarring.
Major RAS (Sutton's disease) is larger ulcers (>10 mm) that are usually associated with medical comorbidities. Healing is slow, over 10 to 40 days. Major RAS usually appears on the lips, soft palate, and throat and tends to heal with scarring.
Herpetiform ulcers, the uncommon RAS, are <5 mm in size. These painful lesions are initially multiple pinpoint sores and usually occur in older individuals. Healing takes about 7 to 10 days.
Pathophysiology
Despite the high prevalence of RAS, evidence is uncertain regarding the etiology. Genetics may play a role, with an immunologic proclivity in 33% to 42% of cases.[4,6] There is a strong immunologic association with genotypes of interleukin (IL)-1 beta and IL-6 in individuals with RAS. Research has failed to find a pathogenic microorganism. Since there is no microorganism associated with RAS, it is not infectious, contagious, or sexually transmitted.[1,4]
In about 80% of people, RAS initially occurs in childhood or adolescence and gradually decreases in frequency and severity over time, resolving by 40 years of age.[4,7] There are many risk factors associated with the development of RAS (Table 1).[1,4,7–9] When onset occurs in an older individual, the cause is often associated with a systemic condition such as Behçet's syndrome, autoimmune disease (e.g., HIV/AIDS), or a gastrointestinal condition. Oral lesions that are seen in systemic conditions are quite similar in appearance to RAS and are referred to as aphthous-like lesions.[1,7,8] These cases may present as major aphthous ulcers. Certain drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs) and nicorandil (a potassium channel blocker), cause RAS-like lesions.[9,10] Illicit use of cocaine (e.g., smoking crack) may cause aphthous-like lesions on the palate.[11]
Management
The clinician must first properly diagnose a person with RAS by ruling out any associated systemic conditions that present with aphthous-like lesions.[7] If a predisposing factor can be identified, it should be eliminated or reduced.
It is important to remember that RAS is benign and neither contagious nor infectious and will heal spontaneously in 7 to 10 days. There are no definitive guidelines for the treatment of RAS. Therefore, palliative treatment is recommended in patients who cannot tolerate the pain. If the ulcer is present for more than 2 to 3 weeks, the pharmacist should advise the individual to see a dentist.[7]
Treatment, for the most part, is empirical and nonspecific (Table 2).[1,4,8,9] A selection of topical agents has been used for palliation to control the condition (i.e., reduce the healing time) and for an analgesic effect (Table 3).[1,2] For minor RAS, palliative medication may not be necessary. However, if needed, topical agents, OTC analgesics, and prescription corticosteroids to reduce inflammation are probably sufficient for the course of the disease. Topical corticosteroids do not reduce the recurrence of the lesions or result in permanent remission, but if initiated at the time of the prodromal stage, may help abort the attack and reduce pain.[1,4] Oral candidiasis and systemic absorption of the steroid through the ulcerated mucosa are of concern.
A topical paste such as amlexanox 5% (Aphthasol), which reduces healing time, accelerates pain resolution, and prevents recurrences, is recommended if there is only one lesion. A mouth rinse is indicated if there are several lesions in the mouth. Topical pastes, liquids, or gels have lidocaine or benzocaine as the active analgesic ingredient. Kank-A Mouth Pain Liquid contains compound benzoin tincture as an oral mucosal protectant. A specific preparation containing Orabase paste (carboxymethylcellulose) is indicated for intraoral use. This agent is compounded with either benzocaine (OTC) for an analgesic effect or triamcinolone for anti-inflammatory effect. When using this product, the patient is instructed to use a finger cot and to dab rather than rub the product on the lesion to allow it to adhere to the ulcer.[12]
Rinsing with a mouthwash (e.g., chlorhexidine gluconate) or water and salt twice a day for 6 weeks is also helpful. Although a bacterial etiology is not recognized as of yet, oral suspensions of tetracycline or doxycycline may be useful in speeding up healing time.[5] Chlorhexidine mouth rinse is preferred over tetracycline for refractory cases because tetracyclines cause enamel discoloration when taken by children under 8 years of age and by pregnant women. Additionally, there is an increased risk of developing oral candidiasis.[13]
Adjunctive dietary and lifestyle management is important. For example, spicy and hot foods, smoking, alcohol, and citrus fruit drinks should be avoided. Since many patients are deficient in vitamin B12, zinc, or folic acid, a supplement can be recommended; however, this association is still unclear and is not advised as first-line treatment.[2,14] Silver nitrate cautery may result in local necrosis and delayed healing.[5,15]
Major RAS and herpetiform ulcers that do not respond to topical agents will most likely require systemic drugs. Those who have them should be referred to a medical or dental specialist. Systemic immunomodulatory agents including prednisolone, methotrexate, colchicine, dapsone, pentoxifylline, thalidomide, interferon alfa, and tumor necrosis factor (TNF) antagonists have been used in resistant cases of major RAS or aphthous ulcers with systemic involvement.[2,16,17]
US Pharmacist. 2013;38(6):43-48. © 2013 Jobson Publishing
