Translucency of Full-contour Zirconia Ceramics

Objectives: The aim of this study was to determine the direct and absolute light transmission coefficients for high-translucency full-contour zirconia (FCZ)" ceramics
Methods: Ten discs ranging in thickness from 0.3 to 0.9 mm thickness by 6 mm diameter were fabricated according to manufacturer’s instructions for each of seven high-translucency full-contour zirconia (FCZ) ceramics
Direct light transmission coefficient was determined using a Varian Cary 5000 Spectrophotometer in the wavelength range 400-800 nm (Varian Instruments, Walnut Creek, CA. USA.) Absolute transmission coefficient was determined using a Ocean Optics USB 4000 spectrophotometer (Ocean Optics Inc., Dunedin, FL, USA) coupled to a Thor Labs Integrating Sphere (Thorlabs Inc. Newton, New Jersey, USA). Light transmission coefficients were obtained from the relationship: I/I_o= t_c^x where I/I_o is the light transmission and x is the sample thickness. Materials used in the study were, Prettau Anterior T0(T0), Prettau Anterior T1 (T1), Prettau Anterior T2(T2), Prettau Anterior T3 (T3), Prettau Anterior T4 (T4), Prettau Anterior BL1(BL1) and Prettau Anterior BL2 (BL2) (Zirkonzahn, Bruneck, Italy).
Results: Direct transmission coefficient for light of wavelength 525 nm, ranged from 0.28(0.03)% for BL2 to 0.44 (0.06)% for T0. Transmission coefficient for T0 was significantly higher than BL1 and BL2 but not significantly different from other materials.(p<0.05) Absolute transmission values ranged from 16.2% for AB1 to 21.72( 0.42) for Anterior T1. T1 and T3 showed the highest absolute transmission values. P<0.05) Absolute light transmission values were significantly lower for AB1 and AB2 than all other materials
Conclusions: The anterior zirconia ceramics investigated showed differences in both direct and absolute light transmission coefficients. Direct and absolute transmission values for FCZ ceramics are comparable to values reported for some conventional dental porcelains.