Space maintainers and regainers are orthodontic appliances designed to preserve or recover space following premature tooth loss. Space maintainers prevent adjacent teeth from drifting, while regainers incorporate active components such as springs or screws to reclaim lost space. These appliances may be fabricated as fixed or removable devices, depending on clinical requirements. They are commonly used in pediatric and Phase 1 orthodontic cases to support proper eruption and alignment of permanent teeth.