A gap (cleft) affecting one of the alveolar ridges, which are the protuberances in the mouth that contain the sockets (alveoli) of the teeth. An alveolar cleft can affect all structures of the alveolar ridge, including the gingiva, other mucosa, periosteum, alveolar bone, and teeth. Alveolar cleft occurs in response to divergence from normal development during frontonasal prominence growth, contact, and fusion. The most common alveolar portion of the cleft is located between the lateral incisor and the canine. [from
HPO]