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. Ø S MODEL Suitable shape to a squared-like cranial morphology, which characterizes a face with pronounced traits, frontal drift and prominent mandibular corners, square chin with squared shaped dental arches Cranial index: mesocefalo 45-65mm