INFLUENCE OF LUTING RESIN CEMENT POLYMERIZATION MODE AND VENEER THICKNESS ON THE COLOR STABILITY OF FELDSPATHIC CAD/CAM VENEERS

Abstract

Introduction: The color stability of the resin-based cement employed for the cementation procedure may be as important for the long-term clinical success of the restoration as the mechanical properties of the veneer. Objectives: The aim of this study was to evaluate the effect of different polymerization modes of resin cements and ceramic thicknesses on the color stability of feldspathic CAD/CAM veneers. Materials and Methods: Sixty-four sound human maxillary central incisor teeth were divided according to ceramic veneer thickness used into two main groups (n = 32); Group I; 0. 5 mm ceramic thickness and Group II; 1 mm ceramic thickness, each group was then subdivided according to the type of resin cement received (Light cure LC or Dual cure DC) into four sub groups of 16 specimens each: Group I A:(0.5 + LC); Group I B:(0.5 + DC); Group II A:(1 + LC); Group II B (1 +DC) . Sixty four Ceramic discs were prepared; for group I, 32 discs of diameter 7 mm and height 0.5mm while for group II, 32 discs of diameter 7mm and height 1mm. The shade was measured using digital spectrophotometer at 3 different time intervals. Results: Ceramic thickness alone revealed statistically significant effect on the ∆E values of all groups (p ≤ 0.05), irrespective of the type of the resin cement. The highest mean ∆E values were recorded in group I A and the lowest ∆E values were recorded in group II B .There was statistically significant difference in ∆E 2 between groups IA and IB. Conclusions: All studied cements showed ∆E within clinically acceptable range in both dual cure and light cure resin cements. Increasing ceramic thickness can serve to mask the underlying color change.