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.  C MODEL Suitable shape for an expanding cranial morphology with wide and rounded dental arches with a low palate, typical of a face roundish contour, in a burly subject. Cranial index: brachycephalic 55-65mm