PURPOSE The purpose of this systematic review was to identify and summarize clinical studies related to the fracture of zirconia abutments in implant treatments. MATERIAL AND METHODS Medline, Embase, and Cochrane library searches were performed and complemented by manual searches from database inception to February 11, 2018, for title and abstract analysis. RESULTS Initially, 645 articles were obtained through database searches. Fifty-three articles were selected for full-text analysis, and 15 studies met the inclusion criteria. The selected studies were analyzed regarding fracture rate, abutment-implant connection, time point of fracture, location of critical crack, causes, managements, and preventive measures with respect to zirconia abutment fracture. CONCLUSIONS Lower fracture rates were reported for internal connection with metal component (2-piece) zirconia abutments compared with external and internal full-zirconia connection (one-piece) zirconia abutments. Overpreparation and overload should be avoided in case of zirconia abutments.
Purpose: Patient-administered and professionally administered periimplant maintenance have been recommended to ensure long-term periimplant tissue health. In this narrative review, the effectiveness of patient and professionally administered interventions and the current level of evidence that periimplant maintenance therapy is effective in preventing the occurrence of periimplant disease were examined. Materials and Methods: A systematic literature search was performed in Ovid MEDLINE, EMBASE, Cochrane Library, and Web of Science, for evidence-based articles in support of the above topics. Results: Twenty-six clinical trials were included and stratified into categories based on topics. Conclusions: The following conclusions were reached: (a) mechanical plaque removal is the foundation of successful periimplant therapy; (b) patient- and professionally administered plaque control has been shown to reduce periimplant inflammation, although complete resolution of inflammation is not always evident; (c) the use of adjunctive chemical agents in maintaining periimplant health still remains to be determined; and (d) regular periimplant maintenance plays a significant role in maintaining periimplant soft and hard tissue health.
