Optical Properties Of Computer Aided Design And Computer Aided Manufactured Materials For Veneer Restorations

Objective:To investigate the translucency parameters（TP）and the color parameters of computer aided design and computer aided manufacturing（CAD/CAM）materials for veneer restorations in order to guide clinical practice.Materials and methods:Eleven groups of CAD/CAM materials（A2 shade）were included in this study:IPS e.max CAD（HT and LT）,IPS Empress CAD（HT and LT）,Lava^TMUltimate（HT and LT）,VITA SUPRINITY（HT and T）,VITA ENAMIC（HT and T）,VITABLOCS Mark II.,and were named as Group A,B,C,D,E,F,G,H,I,J,K.Each material was designed and milled to disk-shaped specimens（10.0mm×8.0mm×0.7mm）（n=6）used by CAM instrument.The specimens were polished with silicon carbide paper and the thickness of specimens were adjusted into 0.60±0.03mm.Some specimens were sintered and glazed according to the manufacture’s direction.The color parameters of specimens were individually measured with the Crystaleye colorimeter against black and white ceramic tiles background to obtain the TP values.The color parameters of the specimens against the composite resin background were also measured to calculate the color differences（ΔE values）between them and the A2shade tab.Results:The translucency parameters of the 11 sets of materials in this experiment ranged from 35.93 to 53.24,the HT and LT specimens of the same material have a large difference in translucency.One-way ANOVA showed that the translucency parameters of the 11 groups of materials were statistically significant（F=253.69,P<0.05）.Under the composite resin background of A2 shade,the color difference between the middle of the specimens and the A2 shade ranged from 1.78 to 4.12,and both are within the clinically acceptable range（△E<5.5）.And among them,VITA SUPRINITY（HT and T）,VITA ENAMIC（HT and T）、VITABLOCS Mark II and IPS e.max CAD LT are within the clinically imperceptible range（△E<2.6）.Conclusions:The microstructure of CAD/CAM materials and the types of material translucency influenced the optical properties.The CAD/CAM materials in this experiment have achieved color matching with the A2 shade tab.And the color differences were smaller between VITA SUPRINITY（HT and T）,VITA ENAMIC（HT and T）,VITABLOCS Mark II,IPS e.max CAD LT and A2 shade tab in this study.