Clinical efficacy of methods for bonding to zirconia: a\ua0systematic review

Statement of problem: The polycrystalline nature of zirconia hinders its ability to bond to tooth structure. Consequently, durable bonding to zirconia has been challenging. In vitro studies have evaluated various methods of bonding to zirconia, but clinical data are sparse. Purpose: The purpose of this systematic review was to critically appraise clinical studies investigating the survival rate of resin-bonded zirconia fixed partial dentures (FPDs), inlay-retained zirconia FPDs, and zirconia veneers. Material and methods: Searches were performed in MEDLINE, EMBASE, PubMed, Web of Science, Scopus, Cochrane Library, and Google Scholar. Clinical studies of over 12 months duration involving bonded zirconia restorations between 1990 and July 2018 were reviewed. All suitable studies were assessed for quality by using a “Questionnaire for selecting articles on Dental Prostheses”. Results: Eight studies were ultimately included. Three studies examined posterior inlay-retained FPDs with estimated survival rates of 12.1% at 10 years, 95.8% at 5 years, and 100% at 20 months. Five studies reviewed anterior, resin-bonded FPDs, all of which had a 3- to 10-year survival rate of 100%. Debonds occurred in all studies, but the prostheses could usually be rebonded. Conclusions: With correctly designed buccal and lingual coverage retainers and minimal if any veneering porcelain, zirconia-based, posterior, inlay-retained FPDs seem to have a high clinical survival rate. The role of bonding efficacy in this survival rate is unknown. Anterior, cantilevered, resin-bonded zirconia FPDs seem to have a high clinical survival rate. While these prostheses can debond, fracture of the entire prosthesis is unlikely, so they may be rebonded. To bond zirconia, the use of airborne-particle abrasion with 50-μm alumina (AlO) at 0.1 to 0.25 MPa in combination with a phosphate monomer-containing adhesive resin is recommended until further studies become available. Rubber dam isolation is also recommended during zirconia bonding