1316 Effect of Glazed Full-Contour Y-TZP on Wear of Glass-Ceramics

Saturday, March 24, 2012: 9:45 a.m. - 11 a.m.
Presentation Type: Poster Session
P. LUANGRUANGRONG1, N.B. COOK2, A.H. SABRAH2, A. HARA3, and M.C. BOTTINO4, 1Restorative Dentistry, Indiana University School of Dentistry, Indianapolis, IN, 2Restorative Dentistry, University of Indiana - Indianapolis, Indianapolis, IN, 3Preventive and Community Dentistry, Indiana University School of Dentistry, Indianapolis, IN, 4School of Dentistry, Indiana University, Indianapolis, IN
The use of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), normally employed as a framework for all-ceramic restorations, have now started to be used without any veneering ceramics in patients with parafunctional activities.

Objective: To evaluate the influence of Y-TZP surface roughness on the wear behavior (volume/height loss) against glass-based ceramics (i.e., IPS Empress CAD and IPS e.max CAD, Ivoclar-Vivadent).

Method: Thirty-two Y-TZP full-contour zirconia (Ardent®) sliders (ϕ=2mm, 1.5mm in height) were milled in a CAD/CAM unit and sintered according to the manufacturer instructions. Sliders were embedded in brass holders using acrylic resin and then randomly allocated into 2 groups according to the surface treatment (n=16): G1-as-machined and G2-glazed (Diazir®). Empress and e.max antagonists were cut into tabs (13×13×2mm) wet-finished and also embedded in brass holders. Two-body pin-on-disc wear test was performed at 1.2Hz for 25,000cycles under a 3-kg load. Non-contact profilometry was used to measure antagonists height (mm) and volume loss (mm3). Qualitative data of the testing surfaces and wear tracks were obtained using SEM. Statistics were performed using one- and two-way ANOVAs (a=0.05).

Result: G1 yielded significantly higher mean roughness values (Ra=0.83mm, Rq=1.09mm) than G2 (Ra=0.53mm, Rq=0.78mm). Regarding antagonist loss, G1 caused significantly less antagonist mean height and volume loss (68.4mm, 7.6mm3) for Empress than G2 (84.9mm, 9.9mm3) while no significant differences were found for e.max. Moreover, Empress significantly showed lower mean height and volume loss than e.max (p<0.0001). SEM data revealed morphological differences on wear characteristics between the two ceramics against Y-TZP.

Conclusion: Within the limitations of this study, e.max wear was not affected by Y-TZP surface roughness. However, Empress wear was greater when opposing glazed Y-TZP. Overall, based on our findings, surface glazing on full-contour Y-TZP did not minimize glass-ceramic antagonist wear when compared with as-machined group.

Study was partially funded by Ivoclar-Vivadent

Keywords: CAD/CAM, Ceramics, Dental materials and Wear