It's difficult to answer without knowing more. Are you referring to a porcelain veneer, a composite filling or a composite veneer?Usually all of the above procedures can match the teeth if a good type of composite or porcelain is chosen, one that matches in both color (shade) and the amount of translucency. If the bonding or veneer is too thin, then that might be reason you see the underlying tooth. Thus, if the dentist did it over, he could drill more of the tooth in his preparation for the bonding, and then the resulting porcelain or composite will be thicker and more apt to cover the part of the underlying tooth you are seeing.I'm sure there is a solution. If your dentist doesn't have one that satisfies you, then get an opinion from another cosmetic dentist.