Space maintainers are metal appliances custom fit for your child's mouth. When baby teeth are lost too soon due to trauma or decay, the other teeth around that area will start to move and fill in the space left by the missing tooth. This is called "space loss." If the teeth are not prevented from shifting, there will not be adequate space for the eruption of the permanent tooth. This often leads to the need for extensive orthodontic treatment. The goal of space maintenance is to hold open that space providing a path for the natural eruption of the developing permanent tooth.