Dentin-Resin Cement Micro-tensile Bond Strength to a Dental CAD/CAM Material

Objectives: With the advent of new CAD/CAM materials the development of resin cements that bond to dentin as well to the milled materials becomes particularly important for the longevity of inlays, onlays, and crowns. The objective of this study was to evaluate the dentin-resin cement micro-tensile bond strength (uTBS) of four resin cements: RelyX Unicem 2 (3M ESPE) [Uni2], Panavia V5 (Kuraray)[Pan5], RelyX Ultimate Adhesive Resin Cement (3M ESPE) [RelU] and Multilink (Ivoclar) [MultiL] to composite resin CAD/CAM blocks (Katana Avencia, Kuraray).
Methods: Non-carious, non-restored human third molars were mounted in dental stone by their notched roots. The occlusal surface was reduced to expose superficial to middle dentin using a 55 carbide bur under copious air-water spray using an electric hand-piece at 200,000 rpm in a custom-made cutting device (CNC Specimen Former: University of Iowa). The tested resin cement systems were applied according to manufacturer’s instructions with their respective bonding system to the dentin surface. The bonded tooth was then stored benchtop for 10 minutes before placing in neutral artificial saliva at 37C. Each tooth was sectioned to obtain four 1 mm x 1 mm specimens using a water-cooled, low-speed Isomet 1000 diamond saw. A crosshead speed of 1 mm/min in a testing machine (Zwick/Roell Z2.5, Zwick GmbH & Co., Ulm, Germany) was used to obtain baseline uTBS at 24 hours post bonding.
Results: The Multilink group did not survive specimen preparation. Therefore, no results were obtained for that group. The means and standard deviation (MPa) for each group were (n=25): RelyX Unicem2: 6.9(1.1), RelyXUltimate: 6.7(1.6), PanaviaV5: 7.2 (0.9). One-way ANOVA followed by Tukey’s test did not show any significant difference among the groups (p=0.36).
Conclusions: The newly FDA approved Katana Avencia block for milled restorations shows acceptable microtensile bond strength values to PanaviaV5, RelyX Unicem2, and RelyX Ultimate evaluated in this study.