Replacement of deciduous teeth with permanent teeth is a physiological process, and as a consequence of early tooth loss in deciduous or mixed dentition, loss of space may occur. There is no doubt that the loss of space after the premature extraction of deciduous molars occurs, however, the width of the lost space and the need for their clinical use are still a topic that is up for discussion. This period is an indication for the designing and installation of space maintainers. The goal of therapy in such situations is to maintain the position of the deciduous dentition in the arch until the eruption of permanent teeth takes place and those teeth take their natural and correct positions. Depending on the method of fixation, space keepers can be fixed, cemented and mobile. These devices are divided by the way they function into active (enable the increase of space by their action) and passive. Space maintainers are a bit neglected, and they represent a very important clinical treatment whose use can bring a lot of benefits, both prophylactic and therapeutic. The development of biomaterials and digitalization in dental practice can direct us to modify and improve this therapeutic method.