A milk tooth serves a very important function of preserving space for the permanent tooth which takes it’s place. Sometimes an early loss of a milk tooth causes drifting of adjoining milk / permanent teeth and space required for the subsequent permanent tooth reduces / closes completely, causing it to stay impacted inside the bone or erupt in an awkward position. Hence, if a milk tooth sheds or has to be removed before the permanent tooth below is formed and is ready to erupt, a SPACE MAINTAINER appliance is given which holds the space required for the permanent tooth till it is ready to erupt in mouth.