[Changes in the posterior vertical dimension of the face. Etiopathogenic factors, architectural criteria and therapeutic aspects].

The ramus of the mandible appears with the cephalic hominisation phenomenous during phylogenesis and determines the vertical posterior height of the face. Among the three skeletal units that form it, the condylar one is responsible of this height and of the level of the posterior part of the occlusal plane. So, all congenital, constitutional or acquired diseases concerning this unit, give a change of the vertical posterior height of the face. The excess troubles ar essentially represented by the condylar hyperplasia, usually unilateral and treated by condylectomy. The vertical posterior insufficiency may be unilateral or bilateral. The former looks like a mandibular asymmetry whereas the latter looks like an anterior vertical excess with or without a Class II malocclusion. If the condyle is absent or T.M.J. destroyed like in ankylosis, the authors use the costo-chondral graft to repair it. But in condylar hypoplasia, they use a vertical osteotomy of the ramus for lengthening the ramus. The three-dimensional architectural analysis is very useful for studying the vertical posterior height of the face and his changes.