Six-Year Clinical Results of Leucite-Reinforced Glass Ceramic Inlays and Onlays

A leucite-reinforced glass ceramic material (IPS-Empress) which had shown for indirectly fabricated inlays and onlays an encouraging 2-year survival rate of 97.5% in a prospective clinical trial was introduced for clinical use at the University of Zürich. The aim of the present study was to assess the clinical behavior of IPS-Empress inlays and onlays with respect to possible fatigue phenomena reported for ceramic systems over five to seven years. The study sample included 43 patients with 138 inlays and 17 onlays. All restorations were cemented with the adhesive technique which included (1) the etching of the inner surfaces of the glass ceramic material with hydrofluoric acid, followed by a silanization and (2) the use of an enamel etching, a dentin and enamel adhesive in conjunction with a composite cementation material. 155 restorations were evaluated with mirror, probe and bite-wing radiographs using modified United States Public Health Service criteria. Restorations recorded as having an Aor a B-rating were defined as successful. Of the 155 restorations, 7 were judged as failures, which resulted in a failure rate of 4.5% for a mean observation time (± std. dev.) of 5.3 (± 1.4) years. Failures were observed between 12 months and 5.1 years after cementation. The estimated Kaplan-Meier survival rate (± S.E.) was 94.9% (± 1.9%) at 6 years for this study sample. Therefore, the clinical behavior of this inlay and onlay material remains favorable after 6 years of function.