[Class II--vertical dimension]

The vertical dimension and its implication in the etiology of the class II are described. This dimension is analysed at the level of the cranial base, the maxillary and mandibular bones and alveolar processes. Then, the facial architecture as a whole is considered and particularly the key position of the upper molar. The dorsal and low position of these teeth in the hyperdivergent cases is fundamentally different from the one they occupy in the hypodivergent cases. The therapeutic approach is completely different in both cases and is illustrated by means of three deep overbite and three open bite cases.