Shade Accurate Composite Modified for Long Preview During Veneer Try-In

Objectives: To compare the effect of various light levels on working times of Accolade PV Cement (PVC) and its system's resin-based Try-In Composite (TIC) with and without presence of a light cure adhesive and to determine shear bond strengths of Prelude/PVC to enamel, dentin and porcelain with and without prior use of the TIC. Methods: Working times were determined using ISO 4049 “Sensitivity to ambient light, Class 2 materials” test. Shear bond strengths were determined using ISO/TS 11405 “A.3.2 Watanabe test” except that shear force was applied by a universal tester (Instron 4411) just five minutes after cement layer polymerization initiation (Demetron Optilux 501). 10 molars for dentin (D), 10 anterior teeth for enamel (E), and 10 Empress porcelain blocks (P) were each assigned to two subgroups (n=5) for bonding with Prelude/AVC after no contact (NOC) or five minutes contact (FMC) by TIC to the surface. Results: Signs of polymerization indicating the end of the working time were evident in 120 seconds or less at 10 klux for PVC and combinations of TIC and two adhesives, Prelude and BondStar E, however, no polymerization was evident even at 480 seconds for TIC under the same conditions. A working time of 240 seconds for TIC alone was found even at 25 klux. Shear bond strengths at five minutes age were: D-NOC = 16.68 ± 1.95 MPa; D-FMC = 19.35 ± 2.77 MPa; E-NOC = 14.58 ± 0.95 MPa; E-FMC = 16.85 ± 0.71 MPa; P-NOC = 19.62 ± 2.84; P-FMC = 17.07 ± 2.32 MPa. Conclusion: Accolade Try-In Composite has sufficient ambient light working time for shade preview. Preview time is greatly reduced in the presence of LC adhesives. Application of Accolade Try-In prior to adhesive does not significantly affect bond strengths to enamel, dentin, or porcelain.