The class 1 appliances are divided in four types of arch shape. They are engaged in basal skeletal disharmonies, responsable for horizontal occlusal deficits, as transverse insufficiences, or vertical ones, as open or deep bites, where there aren’t alterations from class 2 and 3 dental classes. TC MODEL Appliance for the Angle skeletal Class III treatment. It corrects the third skeletal classes repositioning the Class I key jaw. It is indicated in Class III dysmorphosis for the mandibular pseudo-prognathic treatment. It is also indicated for inverse and anterior open bites. It is suitable to procure the arches correct functioning in a regular incisive key relationship, through the upper teeth obtained position in an inner sliding plane and, on the contrary, applying a posterior pressure on the inferior arch, to stop the mandibular growth action. It reconditions the anterior segment, controlling dysfunctional muscle forces with a proper labial competence restoration. It is also indicated for a dysfunctional tongue re-education in a correct rest posture and in correct swallowing.