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Aphthous ulcers They are recurrent and superficial, usually involving movable mucosa, i.e. inner surfaces of lips, buccal mucosa, tongue, floor of mouth and soft palate, while sparing mucosa of the hard palate and gingivae. In the minor form, which is more common, ulcers are 2-10 mm in size and multiple with a central necrotic area and a red halo. They heal in about 2 weeks without leaving a scar. In the major form, ulcer is very big, 2-4 cm in size and heals with a scar but is soon followed by another ulcer. Aetiology of aphthous ulcers: Etiology is unknown. It may be an autoimmune process, nutritional deficiency (vitamin B12, folic acid and iron), viral or bacterial infection, food allergies or due to hormonal changes or stress. Aphthous ulcers can be differentiated from viral ulcers by their frequent recurrence, involvement of movable mucosa as on the soft palate or cheek, and the absence of constitutional symptoms like fever, malaise and enlargement of cervical nodes. Treatment: It consists of topical application of steroids and cauterization with 10% silver nitrate. In severe cases, 250mg of tetracycline dissolved in 50 mL of water is given as mouth rinse and then to be swallowed, four times a day. Local pain can be relieved with lignocaine viscous. Ref:- Dhingra; pg num:-218