Minor aphthous ulcers typically present as small round or ovoid ulcers of 2–4 mm in diameter, occur in groups of up to 6 at a time, and are found mainly on the non-keratinized mucosa of the lips, cheeks, floor of the mouth, sulci, or ventrum of the tongue. They heal in 7–10 days, and recur at intervals of 1–4 months, usually leaving little or no evidence of scarring. They represent 75–85% of all aphthous ulcers.