[Loading and strength of single- and multi-unit fixed dental prostheses. 1. Retention and resistance]

The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and metal-ceramic single-unit fixed dental prosthesis is determined by the configuration's convergence angle, the height, the volume, the interocclusal space, the cervical outline design, the additional preparations, the quality of the (build-up) restoration, and the surface roughness. A silicate ceramic single-unit fixed dental prosthesis is attached through adhesion using a composite cement, but the retention and resistance of an oxide ceramic single-unit fixed dental prosthesis is dependent on the abutment tooth configuration. Most types of multi-unit fixed dental prosthesis have the following additional retention and resistance determining factors: the position in the occlusal system, the number of abutment teeth and their mutual configurations, and the length of (cantilever) pontics. A resin-bonded fixed partial denture's retention and resistance are determined by its bonding as well as its enamel surface coverage and its resistance preparations.