Mobile orthodontic device of a functional type comprises a pair of posterior lateral bites (2) in the form of metal plates connected together by means of a metal wire (4). The posterior bites (2) are designed to be set freely floating between the upper dental arch and the lower dental arch. The device also comprise a pair of vestibular shields (3), made, for example, of synthetic material, associated, respectively, to the two posterior lateral bites (2). The device is without palatal plate, so that the metal wire (4) constitutes the only connection between the posterior lateral bites (2). The device can comprise an anterior bite (6) in the form of a metal plate connected to the two vestibular shields (3) through a second metal wire (5). There may moreover be present one or more lateral expansion springs (7), designed to act on the molars, and one or more anterior expansion springs (8), which act on the incisors.