<prompt> The sign of smooth surface caries in children younger than 3 years of age can be categorized asMild ECCVery mild ECCModerate ECCSevere ECC  <response>: Definition Though the literature does not provide a universally accepted definition for early childhood caries ECC, American Academy of Pediatric Dentistry AAPD defines it as the presence of one or more decayed non-cavitated or cavitated lesions, missing due to caries or filled tooth surfaces in any primary tooth in a child 71 months of age or younger.In children younger than 3 years of age, any sign of smooth surface caries is indicative of severe early childhood caries 7-ECC. From ages 3 through 5, one or more cavitated, missing due to caries or filled smooth surfaces in primary maxillary an teeth or decayed, missing, or filled score of 4 age 3, 5 age 4, or 6 age 5 surfaces constitutes S-ECC. Reference: Pediatric Dentistry Principles and Practice SECOND EDITION, MS Muthu; pdf no 595 