Expansion screw for orthodontics, comprising at least one stem (1) with at least a threaded portion (10) extending along the longitudinal extension of the stem (1), at least one receiving body (3) adapted for receiving said threaded portion (10) and provided with a complementarily threaded hole allowing said threaded portion (10) to be screwed therein, guide means (2) allowing said at least one receiving body (3) to be moved, actuation means (11, 12) for actuating said stem (1). The hole (31) of said at least one receiving body (3) has a longitudinal extension substantially corresponding to that of the threaded portion (10) of said at least one stem (1). The receiving body (3) is a technopolymer receiving body and the stem (1) is embedded in the technopolymer of the receiving body when the expansion screw (100) is made.