When a baby tooth is lost prematurely, it is important to still hold that space so the permanent tooth will still have room to come in. Without holding the space, the teeth will begin to shift and fill in the empty hole. When the permanent teeth do not have room to come in, they will either be blocked out and stay below the gum line, or they will erupt too high and at odd angles. Baby teeth lost too soon almost always guarantees a child will need braces in the near future. Space maintainers are a simple appliance to prevent these problems.