Transmittance of Visible and Blue Light Throught CAD/CAM Materials

Objectives: CAD/CAM materials provide an interesting option for temporary or definitive restorations in dentistry. Milled from monocoloured blocks, the translucency of the materials plays an important role for an esthetically acceptable result.The aim of this study was to compare the transmittance of light in the visible and blue spectrum through CAD/CAM polymer and zirconia materials to a CAD/CAM glass-ceramic material of the same color.
Methods: Polymers - Ambarino High-Class (AM), Telio-CAD (TC), Zenotec PMMA (ZT), Cercon base PMMA (CB), CAD Temp (CT), Artbloc Temp (AT), Polycon ae (PS), New Outline CAD (NC), Quattro Disc Eco PMMA (GQ), Lava Ultimate (LU), Paradigm MZ 100 (PA) and - Zirconia ceramics - Bruxzir (BX), Cercon (CE), Lava Frame (LF), Lava Plus (LP), Prettau (PT), Zenostar (ZS) were tested using a feldspathic glass-ceramic Vita Mark II (MK) as control group. A spectrophotometer measured the overall light transmittance for each material which was calculated as the integration (t_c (l) dl [10^-5]) of all t_c values for the wavelengths of visible light (l:400-700nm) and blue light spectrum (l:360-540nm). Data were analyzed using Kolmogorov-Smirnov test and one-way ANOVA, followed by Scheffe post hoc test.
Results: Zirconia presented significant lowest transmittance of visible as well as for blue light in comparison to all polymers and the control group. The polymers ZT, GQ and NC showed a higher transmittance of visible light than the control group. For blue light, all polymers showed lower transmittance than the control group.
Conclusions: CAD/CAM materials showed visible different translucencies for blue and visible light. This means clinicians should not conclude from the translucency of a material to its permeability for blue light. This influences considerations regarding light curing and clinicians should be aware about the amount of blue light passing through a restoration.