EFFECT OF HEATED COMPOSITE CEMENT AND WEAR WITH DIFFERENT OPPOSING SURFACES ON COLOR OF CAD/CAM CERAMIC OCCLUSAL VENEERS

Statement of problem: improvement and maintain color stability of ceramic restorations is necessary factor for long success of esthetic fixed Prosthodontic restorations. Posterior occlusal ceramic and hybrid ceramic veneers are widely used as a clinical restorative treatment to improve appearance and restore the lost enamel. The abrasiveness limitation of different ceramics materials and its effect on color stability of both enamel and different opposing occlusal restorative materials are very important when selecting as an esthetic restorative material. In addition, recently, composite resin has been used as luting cement for indirect aesthetic restorations. The flow of the pre-heating composite as luting agent improves the adaptation and facilitate the placement of the restoration. Therefore, the effect of heat on color stability of composite as luting agent and its reflection on the color of occlusal ceramic veneers restorations are needed
Objectives: this study was to investigate the effect of heating of flowable composite as luting agent and the wear of occlusal veneer ceramic restoration with different opposing(enamel, e. max and v. enamic) on the color of e. max and vita enamic CAD/CAM posterior occlusal veneers ceramic restorations.
Materials and Methods: 20 extracted human upper premolars were prepared for occlusal veneers were scanned and CAD-CAM restorations were milled using e max and vita enamic CAD/CAM blocks with the same milling parameters. CAD/CAM posterior ceramic occlusal veneers restorations were cemented using flowable composite material before and after heating. Wear of occlusal veneers using chewing simulator (ROBOTA) with different opposing: human enamel, e. max and v. enamic CAD/CAM discs was used. The effect of wear and flowable composite heating on color stability were measured and the data were tabulated and analyzed statistically.
Results: Total effect of heating of composite cement; regardless to occlusal veneers restorations material groups or mechanical wear, it was found that composite resin cement heating affected color stability significantly (p=0.00095 < 0.05) as indicated three way ANOVA test where (non-heated composite cement (ΔE) mean value = 5.94 > heated composite cement (ΔE) mean value = 4.53). Total effect of mechanical wear; irrespective of occlusal veneer material groups or composite resin cement heating, it was found that mechanical wear affected color stability non-significantly (p=0.5776> 0.05) as indicated three way ANOVA test where ( After aging (ΔE) mean value = 5.38 ≥ before aging (ΔE) mean value = 5.09)
Conclusions: selection of the occlusal veneers materials should consider wear properties because the occlusal wear rate varies according to the materials of the occlusal veneers restoration and opposing surfaces as well as the applied load. Moreover, for best aesthetic results, clinicians must be taken in considerations the color, translucency of ceramics and the effects of the luting agent on optical properties.