Effect of Accelerated Aging on Color Stability of Nano Hybrid Ceramics Cemented with Three Types of Resin Cements

Objective: The objective of the current study was to evaluate the effect of artificial aging on the color stability of IPS e.max and CERASMART cemented with 2 types of resin cements and a flowable composite. Materials and Methods: Thirty ceramic disks were machined to a uniform thickness of 0.5 mm and divided into two groups, 15 disks each, according to the type of ceramic material. Each group was then subdivided into three subgroups according to the type of cement used (n=5). Each material was polished according to the manufacturer’s instructions using the same polishing technique and then resin cement was placed with controlled thickness of 0.1 mm by means of a Teflon mold using two resin cements (RelyX Ultimate and RelyX Veneer) and a composite resin (Filtek Z350 flowable composite). A laboratory spectrophotometer was used to measure the color differences (∆E) of each specimen immediately after 24 hours of curing and after artificial aging in a weathering device for 300 hours.
Results: According to Two-Way ANOVA test, both ceramic materials and resin cements are significantly affected by artificial aging. Disks cemented with RelyX Ultimate showed lowest ∆E values (4.75) followed by disks cemented with RelyX Veneer(5.03) and the disks cemented with Filtek Z350 flowable composite represent the highest ∆E values (5.29). Moreover, disks made from CERASMART material showed more color change than disks made from IPS e.max (5.33 and 4.72 respectively).
Conclusion: The color changes of resin cement materials in all groups were above the clinically acceptable value (ΔE ≥3.3). Rely X Ultimate showed higher color stability than the other tested materials. Resin cements affect the final color of thin restorations. IPS e.max CAD showed better color stability than CERASMART CAD.