Space Maintainers help “hold space” for permanent teeth. Your child may need one if he or she loses a baby tooth prematurely, before the permanent tooth is ready to erupt. If a primary tooth is lost too early, adult teeth can erupt into the empty space instead of where they should be. When more adult teeth are ready to come into the mouth, there may not be enough room for them because of the lost space. To prevent this from happening, the dentist may recommend a space maintainer to hold open the space left by the missing tooth.