In Vivo Wear of Glass-ceramic Veneers for Metal-ceramic and Ceramic-ceramic Implant-supported Prostheses

Objectives: (1) To test the hypothesis that there is no difference in the wear of ceramic between two glass-ceramic veneers for metal-ceramic (POM) and ceramic-ceramic (ZP) restorations (IPS InLine POM and ZirPress; Ivoclar Vivadent AG, Schaan, Liechtenstein) used in a clinical study; (2) To test the hypothesis that there is no statistically significant difference in wear of these ceramics between 6 months and 1 year.
Methods: 110 bridges were randomized to receive either a metal-ceramic or a ceramic-ceramic 3-unit implant supported FDP. Implants (OsseoSpeed, Dentsply, Sweden) were placed, custom abutments (Atlantis, Dentsply, Sweden) were fabricated and FDPs cemented. Vinylpolysiloxane impressions (3M Imprint, 3M ESPE) were made at cementation/baseline, 6 months and 1 year. Impressions were poured in stone (Fujirock, GC). Occlusal surfaces of the stone model were scanned for wear using a laserscanner (CS2, Straumann). Statistical analysis was performed using a linear mixed-effects model with a random patient effect. The natural log of the absolute value of wear to meet linear model assumptions was used to analyze the data because the data is highly non-normally distributed.
Results: The mean wear for POM (50.9 ± 32.9) and ZP (127.8 ± 160) after 1 year showed marginally significant interaction between time and material (p=0.083). Across both time points, wear does not differ significantly between POM and ZP (p=0.728). Across both materials there is no significant difference in wear between 6 and 12 months (p=0.514).
Conclusions: Both POM and ZP display typical reported in vivo wear for enamel-enamel antagonists.