Color Stability and Marginal Adaptation of Ceramic Veneers Cemented using Different Composite Resins

Abstract

The present study was designed to evaluate the effect of different resin composite materials used as cement. The materials used was adhesive resin cement, Flowable composite and pre-heated composite and their effect on the color stability and marginal adaptation of lithium di-silicate veneers before and after thermocycling. Upper right central incisor acrylic tooth was embedded up to 2mm below the CEJ to simulate the natural biologic width. Standardized preparations 0.5 mm guided by a 3-wheel diamond depth cutter for labial surface For and 2 mm incisal reduction from the cervical line as butt joint preparation. For color stability and marginal adaptation testing, a total of 21 replicated upper central die (n=21) will be randomly assigned into three groups of 7 dies each (n=7) according to the type of cement used into Group I, II & III. Each abutment was scanned with the Primescan. Twenty-one laminate veneers were designed on the scanned abutments, using CEREC SW 3D software (V5.2.1). and milled with MCXL. Emax veneers manufactured by MCXL machine fitted well to the epoxy die without any adjustments to the inner surface of the veneers by the dental technicians. For the resin cement group, the adhesive resin cement shade A1 was applied on the fitting surfaces of the ceramic laminate veneers. The veneer was seated on the abutment tooth following its path of insertion and sustained with special loading device (1kg). For the flowable composite group, the cementing procedure steps were followed using shade A1filtek z350 xt flowable composite.In the pre-heated composite resin groups, the composite syringe filtek z350 xt shade A1was placed in a composite heater and pre-heated at 60Oc for 3 mins. After the heating period, the same cementing procedure were followed. After cementation, the aging of resin-based materials has been simulated in vitro by thermocycling. The three subgroups were placed in the thermocycling device for 5000 cycles to simulate aging process. Color stability of all laminate veneers was evaluated using spectrophotometer after cementation and after thermocycling. Vertical marginal gap of all laminate veneers was evaluated using digital microscope before, after cementation and after thermocycling. Shots of the margins were taken for each veneer using digital microscope cervical, incisal and proximal. One-Way ANOVA followed by Tukey’s post-hoc test were also used to compare ΔE mean and marginal gap values between cement type groups. Paired sample t-test was used to compare marginal gap mean values before and after cementation, as well as after cementation and after thermocycling within each cement type group.