[Cervical limits and contour forms as a function of material technology]

The objectives of tooth preparation for porcelain crowns are emphasized in this article. The forms of contour described by Gonon, LE Huche, Poggioli and Leibowitch are reviewed in the first part. In the second part, the profile of the cervical limits and their evolution are described, according to the materials used. The importance of the marginal fit, in relation to microleakage and esthetics, is related in the third part.