Translucency Comparison of CAD/CAM Materials

Objective: To compare the translucency of eight core and five full-contour CAD/CAM materials using reflectance contrast ratio as a method of measurement.Methods: Seven core materials were tested: a.Lava (3M/ESPE); b.Incoris ZI (Sirona); c.YZ-55 (Vita); d.Cercon (Dentsply); e.Inceram Spinell (Vita); f.Inceram Alumina (Vita); g. Inceram Zirconia (Vita). Five full-contour materials were tested: a.Paradigm C(3m/ESPE); b. Vitamark II (Vita); b.E.max CAD (Ivoclar); c,d.Empress CAD HT and Empress CAD LT(Ivoclar). Reflectance measurements of core and full contour materials were determined on disc specimens 1.5 and 0.5mm thick, respectively. By sectioning the blocks of relevant materials, specimens were produced. Lava, Incoris ZI,YZ-55 and Cercon specimens were sintered , Inceram specimens were glass infused and e.max CAD specimens were fired for crystallization according to manufacturer instructions. All specimens were tested in a spectrophotometer (i5,X-Rite, GretagMacbeth) across the visible spectrum (400-700nm) with CIE standard illuminant D65. Contrast ratios (CR) were calculated from the luminous reflectance of the specimens on a black surface (Yb) to the reflectance on a white surface (Yw), (CR=Yb/Yw). One way analysis of variance(ANOVA),two sample t-test and Satterthwaite-Welch t-test were used.

Results: Mean contrast ratios are shown below:

Core Materials	Lava	Incoris ZI	YZ-55	Cercon	Inceram Spinell	Inceram Alumina	Inceram Zirconia
Contrast Ratio	0.69 (0.024)	0.9 (0.006)	0.71 (0.01)	0.77 (0.017)	0.65 (0.07)	0.77 (0.02)	0.99 (0.16)
Full contour materials	Paradigm C	VitamarkII	E.max CAD	Empress CAD HT	Empress CAD LT
Contrast Ratio	0.69 (0.009)	0.71 (0.02)	0.83 (0.007)	0.69 (0.01)	0.76 (0.014)

Conclusion: ANOVA test revealed differences between both groups of materials. At a =0.05 Anova and t-tests indicate the following ranking of materials according to contrast ratio (from most translucent to most opaque).Core materials: Inceram Spinell> Lava,YZ-55>Cercon,Inceram Alumina>Incoris ZI>Inceram Zirconia. Full contour materials: Paradigm C,VitamarkII,Empress CAD HT> Empress CAD LT>E.max CAD.