Masking Ability of Zirconia with and without Veneering Porcelain

Abstract

While zirconium oxide coping material alone has a degree of masking ability, the resulting color of a restoration can be further modified with the veneering porcelain.

The influence of colored zirconia on the optical properties of all-ceramic restorations

“…When veneering ceramics were layered above TZP cores, TP for all shades decreased to values from 1 to 3 exhibiting minimal translucency. TZP particles are slightly bigger than wavelength of visible light and also have different refractive indexes than the matrix, giving maximal scattering effect and opacity, which explains the lack of translucency in other words, the masking effect of TZP 13,17) . In addition Choi et al reported that the resulting color of restoration can be modified with the veneering porcelain, which is also in agreement with our conclusion 13) .…”

“…If we were to indicate the cause of color difference between the core colors, it would be the lack of the shade base layer which affected L* and a* for A1 and L* and b* for A4. When properly veneered, colored TZP frameworks are said to produce clinically acceptable color match and have the capacity to mask a dark background such as a dark tooth or core buildup material 13,31) . Our results are consistent with studies reporting that the veneering ceramic is what modifies the final color of ACR 9,13) .…”

“…The addition of veneering ceramic on TZP cores to improve esthetics diminishes their advantage over ACR made of only feldspathic porcelain in terms of tooth reduction 11) . Its opaque nature and masking ability have demonstrated that TZP restorations require less tooth reduction than traditional feldspathic porcelain to sufficiently mask undesirable tooth colors [11][12][13] . The optical properties of ceramic restorations could be influenced by thickness, surface texture, brands, batches, and number of firings of the porcelain, in addition to properties of the luting agent and abutment 9,[11][12][13][14][15][16][17][18][19][20][21] .…”

“…Its opaque nature and masking ability have demonstrated that TZP restorations require less tooth reduction than traditional feldspathic porcelain to sufficiently mask undesirable tooth colors [11][12][13] . The optical properties of ceramic restorations could be influenced by thickness, surface texture, brands, batches, and number of firings of the porcelain, in addition to properties of the luting agent and abutment 9,[11][12][13][14][15][16][17][18][19][20][21] . Light transmittance and reflectance have important roles in the aesthetics of restorations and translucency is a property that is dependent on light scattering and absorbing characteristics as it contributes to the lifelike and natural appearance to ceramic restorations 22,23) .…”

“…However, the above mentioned studies on the optical properties of ceramics leads to the question of whether or not the use of different TZP core colors would cause perceptible color differences on the final TZP restoration after veneering ceramics compared to when non-colored TZP are used. There have been few or some reports on the masking ability of TZP and the correlation between the thickness ratio of ceramic core and veneer on the final restoration color 13,[26][27][28] , however not much information has been published on optical aspects of ACR using colored TZP.…”