The American Dental Association recommends wiping baby's gums with a clean gauze pad or a wet washcloth after feedings even before the teeth appear to prevent plaque build up and bacteria from harming teeth still under the gumline.
Mild build - up may be eliminated, but keep in mind that, although gum pockets and tartar accumulation under the gumline are common, a proper dental examination by your veterinarian should still be done.