Buccal:

relating to the cheek, especially the membranes lining the inside of the cheek. 
The cheek-facing side of a postcanine tooth. 

adjective, Latin bucca = cheek. 

Pertaining to, adjacent to, or in the direction of the cheek 
Lying within the mouth; "a buccal gland". 
Toward the inside of the cheek; "the buccal aspect of the gum".