[Resistance and retention as critical factors in silver amalgam restoration of endodontic posterior teeth. A clinical focus].

The root canal therapy does not make sense if it is not going to be restored properly. Even though we must keep in mind all the steps necessary to build up any vital tooth, we should emphasize the retention and resistency due to the fragility of endodontically treated teeth and to the destruction of these teeth. Even though the use o silver amalgam has been often questioned, we still consider amalgam as a proper material of a good half worm life to build up endodontically treated posterior teeth. Resistency and retention were considered as the essential factors to achieve the integrity of final restorations. We have analyzed the remaining tooth structure, periodontal support, biomechanics properties of the most used restorative materials and the variations of the forces. The different opinions on the concepts and technics have been reviewed and the final practical conclusions discussed.