Aphthous stomatitis (Canker sores, recurrent aphthous stomatitis, RAS)

DESCRIPTION:   This is one of the most common oral diseases. The exact incidence is unknown, but estimates range from 20% to 60% of the population. Lesions appear as painful ulcers ranging in size from less than 1 mm to 2 centimeters. They may be single or multiple. Small lesions (less than 0.5 cm) have been referred to as minor aphthae (Fig. 1) and large lesions (more than 0.5 cm) have been called major aphthae (Fig. 2).
An uncommon presentation of this disease appears as multiple, pinpoint areas of ulceration that seldom exceed 1 mm (Fig. 3). This has been referred to as the herpetiform pattern, an unfortunate terms since herpes virus is not the cause.
Each lesion begins as a red macule, less often a papule but not as a blister. It soon ulcerates and the ulcer becomes covered by a pyogenic membrane producing the characteristic yellow-white center with surrounding erythematous flare. The shape is usually round to oval but may be elongated in natural folds such as the vestibule.

Aphthous stomatitis occurs on freely movable mucosa that does not overlie bone. The lips, cheeks, soft palate, floor of mouth, ventral and lateral tongue are often involved but attached gingival, hard palate and dorsal tongue are seldom affected.
Aphthous lesions affect all age groups from young to old but young adults and females are more affected. Elapsed time between recurrences is extremely variable; some unfortunate patients have almost continuous disease whereas others go from months to years between episodes.

ETIOLOGY:  The cause is unknown. The concept that canker sores are caused by a microbiologic agent has been superceded by theories revolving around an immunopathogenesis. The deposition of antibodies and complement within epithelium and basement membrane during the early stages of the disease suggests a humoral immune response, and the  influx  of  lymphocytes  rather  than  neutrophils  in  early  lesions  points  to  a  cellular immune reaction as well. It is yet to be learned if the immune response is directed against self (autoimmunity) or against an extrinsic antigen such as bacteria or viruses. To further cloud the issue, a variety of other factors have been implicated.
Withdrawal of certain foods such as cheese, tomato products and gluten, as well as sodium lauryl sulfate-containing tooth pastes, has been claimed to help some patients whereas in others, correction of iron, B12 and folate deficiencies have brought about a cure. Improvement of aphthous lesions during the last stages of pregnancy with exacerbation after delivery suggests that gonadal hormones may lay a role. The occurrence of canker sores during menstruation also suggests a hormonal basis. To add a final element of mystery, aphthous stomatitis has been reported to worsen when cigarette smoking is discontinued. There are too many theories for them all to be correct. Aphthous stomatitis may not be a single disease with a single cause but instead a variety of diseases all manifested by painful mouth sores.

TREATMENT:   To reduce pain, patients with few lesions may be treated with topical medications such as Orabase  ® with Benzocaine, Zilactin ®, or Soothe-N-Seal  ®. Anti-inflammatory agents such as topical steroids or Aphthasol  ® have also been shown to be effective. For severe or widespread disease, systemic prednisone such as a Medrol 4 mg Dosepak  ® is helpful. Long-term systemic steroid therapy may be associated with numerous adverse effects, including osteoporosis, asceptic necrosis, cataracts, depression, fluid retention and exacerbation of diabetes.

PROGNOSIS:  Cure is seldom achieved but palliation and long-term remission may be achieved by above mentioned treatment. Without treatment, healing time varies from 4 days for a small lesion to a month or more for major aphthae. Major aphthae may also cause scarring.

DIFFERENTIAL DIAGNOSIS:  Aphthous stomatitis must be differentiated from herpetic stomatitis, the disease with which it is most often confused. Recurrent intraoral herpes occurs almost exclusively on mucosa overlying bone. The hard palate is the most common site. Lesions indistinguishable from aphthous stomatitis have been reported in Behcet's syndrome, Reiter's syndrome, Crohn's disease and celiac disease.

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