Color masking effect of ultra-opaque resin cement with different ceramic systems : (An in-vitro study) /

Abstract

Cement criteria considered as one of the important factors that influence shade on dental restorations. The perceived shade of restoration by the naked eye affected by cement type, thickness, shade and curing method. Aim of study was to test the effectiveness of the Ultra-Opaque luting cement (Vita Adiva IA-Cem) compared to the conventional one (Breeze) on masking the metal Ni-Cr substrate covered with three ceramic materials and evaluating its color stability after thermocycling. A total of 60 disc-shaped specimens were machined out of three types of monolithic CAD/CAM ceramic blocks: IPS e.max CAD, Vita Suprinity, and Katana ultra-translucent zirconia; 20 samples for each material. Shade A2 MT was chosen for the three materials. A total of 60 Ni-Cr metal disc shaped specimens were manufactured using a customized teflon mold with dimension 10mm X 1mmto and lost wax technique be adhesively cemented to ceramic one. CAD/CAM ceramic blocks were milled into cylinders with dimensions 10 mm diameter and 14 mm long (for e.max and vita suprinity) and 11 mm diameter and 14 mm long (For Katana zirconia). The cylinders were then sliced into discs with 1 mm thickness by using diamond sawing machine. The IPS e.max and Vita suprinity samples were crystalized and glazed in one step inside a firing furnace, Katana samples were also sintered and glazed in one step inside a sintering oven as well. For IPS e.max CAD and Vita Suprinity specimens, surface treatment was done using 9% hydrofluoric acid& rinsed for 1 minute under water spray and then silane coupling agent was applied for 1 minute. For Katana specimens, zirconia primer was used to apply one drop on the zirconia specimens before cementation as well. The metal disc specimens were then placed inside another custom made split teflon mold machined with the dimensions of 10mm X 2.1 mm and then the cement was applied on it using mixing tip to be cemented to the ceramic one under standard weight of 1 Kg. A portable Spectrophotometer was used to measure the baseline color of the specimens before cementation, after cementation of ceramic specimens to metal one and after being subjected to thermocycling process. Color masking and color changes results (DE) were obtained using equation DE = [(D L*)2 + (D a*)2 +(D b*)2] ½.