Abstract: The invention relates to a fixed lingual orthodontic appliance which, when installed on the patient, rests on the lingual surface of the teeth and the palatine and inferior alveolar mucous membranes, comprising a base and support element (1) destined to be rested on the oral mucous membrane, substantially horseshoe-conformed, a plurality of elastic connecting elements (2) made by the modelling of a steel wire or similar with predetermined elastic characteristics, fixed at an end to the base and support element (1), and at the other of its ends on a respective bracket (3), the bracket or brackets (3) being made in synthetic resin and in a number which is equal to that of the teeth to be treated, and being conformed in such a way as to exhibit a concave face (7) which will be cemented on the equally concave lingual surface of the tooth, the other, convex, face (8) exposed to the oral cavity being superficially perfectly smooth and having a convexity which is equal to the development of the corresponding surface