Kroneprepareringer og retensjonselementer

Abstract

Crown preparation design754-61.Biological, mechanical, and aesthetic considerations must be made when preparing a tooth for crown therapy. The finish line, occlusal reduction, and general shape of the preparation must be adjusted to the desired crown material, the location of the vital pulp, and the luting cement that is to be used. A knife edge is primarily used for metal based-crowns while a shallow chamfer is used for metal-based crowns and monolayer ceramic crowns and veneers. A deeper chamfer is used for all-ceramic crowns with a high strength ceramic core and for metal ceramic crowns in the areas where the veneering ceramic covers the metal to the finish line. The remaining tooth substance must be used to fully exploit its retentive potential. Usually the teeth are damaged in a way that makes an ideal preparation impossible. The dentist must then make proper adjustments of the preparations to ensure adequate fixation against crown loosening. Steps, groves, boxes, or pins can increase both the retention and resistance form of a preparation. Alternatively, adhesive resin-based cementation can be used with all-ceramic crowns without high-strength cores.The crowns that require the least tooth substance removal, such as metal crowns or resin retained monolayer ceramic crowns, should be used when possible, in order to avoid unnecessary removal of tooth substance or damage to the pulp.