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Aphthous ulcerations, or RAS (Recurrent aphthous stomatitis) also known as RAS-like ulcerations, are not solely a local condition but rather have an underlying systemic cause. Therefore, they should be recognised as a distinct medical condition. It is important to consider and differentiate them from other conditions, such as autoinflammatory syndromes (e.g. PFAPA syndrome, Behçet’s syndrome, Crohn’s disease) and immunodeficiency states (e.g. nutritional defects, immune defects, neutrophil defects) in order to establish the correct diagnosis. However, when ulceration is present without any associated systemic disease, the term RAS (Recurrent Aphthous Stomatitis) can be used.

The prevalence of RAS varies among different populations. In the United States, the prevalence was reported to be 0.89% in adults and 1.64% in children during the period of 1988-1994. In other countries such as Iran (2005), Jordan (2008), India (2010-2012), and China (2013-2017), the reported prevalence was 25.2%, 70%, 21.7%, and 27.17%, respectively. RAS tends to occur more frequently between the ages of 10 and 19, with its frequency decreasing as individuals age.

Diagnosing RAS primarily relies on clinical examination, and biopsies of ulcers should only be performed when there is uncertainty or suspicion of an oral disease causing ulcers or malignancy. Microscopically, the characteristics of RAS are nonspecific. The pre-ulcerative lesion exhibits subepithelial inflammatory mononuclear cells with abundant mast cells, connective tissue edema, and neutrophils along the margins. Epithelial damage typically starts in the basal layer and progresses through the superficial layers, leading to ulceration and surface exudation.

RAS commonly occur in the second decade of life, between 20 and 30 years of age. RAS are characterised by their painful nature, slow healing, and potential for scarring. Typically, these oral lesions are larger than 1 cm in diameter. 

RAS can be classified into three types: minor, major (also known as periadenitis mucosa necrotica recurrent), and herpetiformis. The minor type is the most common, with ulcers usually smaller than 5 mm in diameter, round or oval in shape, and accompanied by a grey-white pseudomembrane and erythematous halo. They are typically found on non keratinized surfaces of the oral cavity, particularly the labial buccal mucosa and floor of the mouth, but rarely on the gingiva, palate, or dorsum of the tongue. Minor RASs heal within 10-14 days without scarring. 

Major RASs, on the other hand, are larger, exceeding 1 cm in diameter, and primarily occur on the lips, soft palate, and fauces. These ulcers persist for up to 6 weeks and often heal with scarring. Major RASs are typically observed after puberty and may persist for 20 years or more. 

Herpetiform ulcers, affecting 1%-10% of RAS patients, are characterised by small, painful, multiple ulcers that recur frequently and are widespread. At any given time, a patient may have up to 100 ulcers, each measuring 2-3 mm in diameter. 

Despite the name, herpetiform ulcers are not associated with herpes viruses. RAS can lead to swallowing difficulties, nutritional deficits, and reduced quality of life. Symptoms are often more severe in immunocompromised individuals. 

The main focus of therapeutic options is to alleviate painful symptoms. Dental surgeons typically inform patients that ulcers will likely heal within two weeks. In more complex cases, treatment may involve the use of topical corticosteroids, which is also the approach used for other diseases with unknown causes, such as pemphigus, pemphigoid, and oral lichen planus. However, the evidence for the efficacy of topical corticosteroids in RAS is limited, and even less evidence exists for systemic interventions. The recommended treatment protocol combines a topical corticosteroid, a topical anaesthetic, and a buccal antiseptic. This combination may include triamcinolone (0.1% paste, up to four times daily), topical lidocaine (2% viscous solution, maximum 8 doses/day), and oropharyngeal chlorhexidine (0.12%, 15 ml mouthwash twice daily) as an adjuvant. Patients should also be advised to avoid trigger foods, as well as acidic foods and drinks.