Biological influence of some crown and bridge restorative materials finished and polished by different techniques.

Fixed restorations should satisfy certain biologic requirements and they must not be injurious to the surrounding living tissues as pulp, periodontal ligament, alveolar bone and gingiva. It is best to terminate preparations above the gingival margin but for retention and esthetics considerations the margins of the fixed restorations could be placed subgingivally. In recent years, the biologic effects of dental restorative materials on the gingiva and periodontal tissues have been better appreciated. A rough surface restoration attracts and retains bacterial plaque and irritates the surrounding soft tissues which is injurious to the living supporting structure of the abutments.