Zirconia implant abutments: A review

PURPOSE: The aim of this study was to evaluate in vitro the microgap between different zirconia abutments and their titanium implants. MATERIALS AND METHODS: Four systems were evaluated: Procera zirconia (Nobel Biocare) (Nb), Cercon Balance Anterior (Dentsply Friadent) (Ba), ZirDesign (Astratech) (Zd), and Straumann Cares ceramic (Straumann) (Ca). Five assemblies were assessed for each system. The assemblies were embedded in epoxy, cut along their long axes, and polished. Scanning electron microscopic observations were made along the first 100 microm of the gap on each side at maximal magnification. Images were combined and gap measurements were made 10 microm apart. A two-way analysis of variance was performed on the data. RESULTS: Scanning electron micrographs showed a mean marginal microgap of 0.89 microm (SD 1.67) for all assemblies. Significant differences (P < .001) were observed between mean (+/SD) microgap measurements of the four tested systems: Ba = 0.38 +/0.28 microm; Zd = 0.55 +/0.23 microm; Nb = 1.83 +/3.21 microm; Ca = 0.90 +/0.59 microm. The mean microgap of the first 20 microm of the outer region (1.66 microm) was significantly (P < .001) larger than the mean microgap (0.56 microm) of the inner region (30 to 100 microm). CONCLUSIONS: Within the limitations of this study, the mean microgap observed for all tested systems was less than 2 microm. For each system, the microgap decreased quickly from the outer region to the inner. The mean gap was larger for flat-to-flat connection systems, compared to internal-connection systems with a conical interface. These results demonstrate smaller microgaps compared to those described in the literature for titanium abutments. The precise fit of these abutments could lead to better biologic and biomechanical behavior. An overview of zirconia ceramics: basic properties and clinical applications. Manicone PF, Rossi Iommetti P, Raffaelli L. J Dent. 2007 Nov;35(11):819-26. Epub 2007 Sep 6. Catholic University of Sacred Heart, Institute of Clinical Dentistry, Largo F.Vito 1, 00168 Rome, Italy. Abstract Zirconia (ZrO2) is a ceramic material with adequate mechanical properties for manufacturing of medical devices. Zirconia stabilized with Y2O3 has the best properties for these applications. When a stress occurs on a ZrO2 surface, a crystalline modification opposes the propagation of cracks. Compression resistance of ZrO2 is about 2000 MPa. Orthopedic research led to this material being proposed for the manufacture of hip head prostheses. Prior to this, zirconia biocompatibility had been studied in vivo; no adverse responses were reported following the insertion of ZrO2 samples into bone or muscle. In vitro experimentation showed absence of mutations and good viability of cells cultured on this material. Zirconia cores for fixed partial dentures (FPD) on anterior and posterior teeth and on implants are now available. Clinical evaluation of abutments and periodontal tissue must be performed prior to their use. Zirconia opacity is very useful in adverse clinical situations, for example, for masking of dischromic abutment teeth. Radiopacity can aid evaluation during radiographic controls. Zirconia frameworks are realized by using computer-aided design/manufacturing (CAD/CAM) technology. Cementation of Zr-ceramic restorations can be performed with adhesive luting. Mechanical properties of zirconium oxide FPDs have proved superior to those of other metal-free restorations. Clinical evaluations, which have been ongoing for 3 years, indicate a good success rate for zirconia FPDs. Zirconia implant abutments can also be used to improve the aesthetic outcome of implant-supported rehabilitations. Newly proposed zirconia implants seem to have good biological and mechanical properties; further studies are needed to validate their application. Clinical trials in zirconia: a systematic review. Al-Amleh B, Lyons K, Swain M. J Oral Rehabil. 2010 Aug;37(8):641-52. Epub 2010 Apr 9. Department of Oral Rehabilitation, Faculty of Dentistry, University of Otago, Dunedin, New Zealand. [email protected] Abstract Zirconia is unique in its polymorphic crystalline makeup, reported to be sensitive to manufacturing and handling processes, and there is debate about which processing method is least harmful to the final product. Currently, zirconia restorations are manufactured by either soft or hard-milling processes, with the manufacturer of each claiming advantages over the other. Chipping of the veneering porcelain is reported as a common problem and has been labelled as its main clinical setback. The objective of this systematic review is to report on the clinical success of zirconia-based restorations fabricated by both milling processes, in regard to framework fractures and veneering porcelain chipping. A comprehensive review of the literature was completed for in vivo trials on zirconia restorations in MEDLINE and PubMed between 1950 and 2009. A manual hand search of relevant dental journals was also completed. Seventeen clinical trials involving zirconia-based restorations were found, 13 were conducted on fixed partial dentures, two on single crowns and two on zirconia implant abutments, of which 11 were based on soft-milled zirconia and six on hard-milled zirconia. Chipping of the veneering porcelain was a common occurrence, and framework fracture was only observed in soft-milled zirconia. Based on the limited number of short-term in vivo studies, zirconia appears to be suitable for the fabrication of single crowns, and fixed partial dentures and implant abutments providing strict protocols during the manufacturing and delivery process are adhered to. Further long-term prospective studies are necessary to establish the best manufacturing process for zirconia-based restorations. Recent advances in materials for all-ceramic restorations.