1, abnormal attachment or short deformity of lingual frenulum is the most common congenital malformation except alveolar ridge. The baby's lingual frenulum is too short and deformed. Because the frenulum often rubs the lower incisors when the tongue is extended forward, bedsore ulcers may occur. The incisors of deciduous teeth have erupted after 6-9 months due to the infant's dysplasia, and the lingual frenulum is still attached to the alveolar ridge on the lingual side of the mandible, which restricts the movement of the tip of the tongue so that it cannot extend out of the mouth, or forms a groove when the tip of the tongue extends forward, and the tip of the tongue cannot roll up and contact the upper teeth, resulting in the lingual frenulum being too short.

2. For edentulous patients, the attachment of lingual frenulum or maxilloglossal muscle is close to the crest of alveolar ridge, which often hinders the placement and retention of denture.