Many new parents don't realize that even as infants, your children are going to want toothbrushes, and basically using an adult toothbrush and being careful isn't going to get the job done. That's why there is a whole line of infant toothbrushes that feature short handles so they are extra controllable in the tiny mouth of an infant and super soft bristles that won't cut up your infants cheeks or gums.
Source: http://omgstroller.com/best-baby-toothbrush-reviews/