Acrylic veneers are commonly used in RPD's, (especially telescopic retained dentures) because of several advantages. Particularly the flexibility of the resin is needed to withstand the inevitable minor deformation of the metallic framework. In the recent years different bonding systems (i.e. Rocatec, Espe and Silicoater, Heraeus Kulzer) have been introduced to enhance the durability of the metal-resin interface and to improve shear bond and flexure strength of the entire system. Since there is only little information about the clinical durability of resin veneered telescopic crowns, it was therefore the aim of this in-vivo study to analyze three acrylic systems in a prospective randomized clinical trial. The veneer materials Dentacolor, Artglass(Heraeus Kulzer) and Sinfony (Espe), using the silanization methods recommended by the manufacturer (Siloc: Heraeus Kulzer; Rocatec: Espe), were chosen randomly to veneer a total of 323 telescopic crowns in 95 patients. The patients were subjected to a continuous recall-program. The veneers were evaluated; examination criteria were complete or partial loss of veneers (1/3;, 2/3; complete loss veneer) and a change in color compared to neighboring teeth. Statistical analysis was performed using the survival-analysis by Kaplan-Meyer. The following table shows the results of the different materials after 18 month. Material Loss veneers 1/3 2/3 Complete loss Discoloration of veneer Dentalcolor/Siloc n=120 5% * 1 % 7 %* 2 % Artglas /Siloc n=97 14 %* 0 % 28 %* 4 % Sinfony/Rocatec n=106 9 %* 0 % 0 %* 9 % Keywords: dental materials, microbiology, composite, amalgam