IM0410

research _ dental surfaces I forcesofocclusiondirectlyonthezirconiacorema- terial and the possible effects of direct contact with the zirconia core on the opposing dentition. In both situations two—surface (body) wear will occur re- sultinginlossofbothenamelandrestorativemate- rial. The goal of restorative dentistry is to develop a restorative surface that has the same wear charac- teristics as human enamel. Thespecificaimofthisstudywastocomparethe in vitro wear characteristics of human enamel againstazirconiabasedcorematerialwithtwosur- face finishes and various zirconia and aluminium oxide specific porcelains. The zirconia core material was studied in its as-manufactured state and after undergoing polishing with a proprietary polishing kit and diamond polishing paste. The dental porce- lainsurfacesunderwentvarioussurfacetreatments of which the polishing process was identical to that appliedtothezirconia,allowingadirectcomparison of zirconia and porcelain surfaces. A polished type IV gold surface acted as the control surface for the wearstudy.Laservideography(Mitutoyo/MTIcorp. AuroraIll™)wasthemethodemployedtoassessthe wearthatoccurredontheporcelain,goldandzirco- nia samples as a result of abrasion by human enamel, however, only the enamel wear data will be presented here. _Materials and Methods Discs of YTZP stabilised zirconia core material 13.0mmindiameterand2.00mminthickness(Figs. 1 & 2) were supplied by the manufacturer (Procera; Nobel Biocare, Kloten, Zurich, Switzerland). For the purposes of the article the term “zirconia” will equate to “YTZP stabilised zirconia core material”. Discs of type IV gold of the same dimensions were fabricatedbytheexaminertoserveasacontrolsur- face—“G”intheresultstablesandgraphs.Thezirco- nia samples were divided into two groups: _Theasmanufacturedgroup—“Za”intheresultsta- blesandgraphswiththesurfacefinishasdelivered from the manufacturer (Procera; Nobel Biocare, Kloten, Zurich, Switzerland). _The polished group—“Z” in the results tables and graphs—the test surface of the zirconia samples underwent polishing with a proprietary polishing system (Dialite ceramic polishing system, Bras- seler™)anddiamondpolishingpaste(Ultradent™). Discsofdentalporcelains20mmindiameterand 3–5mm in thickness were supplied by the various manufacturers outlined below (Fig. 3). The dental porcelains underwent three separate surface treat- ments, specifically: _Application of an external glaze (powder glaze). _Autoglazing (self glaze procedure). _Mechanicalpolishing(samemethodusedwiththe zirconia core material). The dental porcelains evaluated in the study were: _CZR Cerabien—Zirconia specific porcelain (Nori- take™)—“C” in results tables and graphs. I 15implants4_2010 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9