When the cavities are very deep and the tooth needs a baby root canal ( aka Pulpotomy) where the nerve needs to be removed from the crown portion of the tooth and a medicament is placed in the tooth. In such scenarios it is necessary to cap the tooth to increase the life of the tooth. It is important to use the baby tooth as a natural space maintainer, if is possible, to keep the space for the permanent tooth developing underneath. That’s why is very important to have healthy baby teeth.