In many cases, yes. Without a space maintainer, adjacent teeth may drift into the empty space, reducing room for the permanent tooth, which is usually larger than the primary tooth.
Space Maintainers are recommended when a primary tooth has been recently extracted and adequate space remains for the permanent tooth.
Space Regainers are recommended when a primary tooth was lost some time ago and the space has already narrowed. They help reopen space so the permanent tooth can erupt properly, reducing the risk of crowding and the need for orthodontic treatment in the future.