[Morphological changes in the periodontium from the use of different designs of metal ceramic dentures]

Morphological changes in the periodontium during the use of cermet crowns of different design were studied in experimental animals. The status of the periodontium was found to depend on the level of crown fixation with respect to gingival edge. Histological findings had show that position of a cermet crown at the level of the gingival edge does not involve appreciable changes in the periodontium, though preparation of abutment teeth with the formation of a step be considered as preferable. A subgingival position of cermet crowns leads to development of an inflammatory reaction in the periodontium, the severity of this reaction being related to a great measure to the method of the tooth preparation. If a step is formed during preparation of a tooth, the inflammatory changes are less pronounced than when there is no step formed. In the latter case the pathological changes were seen in the periodontium. The authors come to a conclusion that cermet crowns should be fixed at the level of the gingival edge. When making cermet crowns, abutment teeth should be prepared with the formation of a pericervical step.