Effect of pattern materials and fabrication techniques on the color of a pressed lithium disilicate ceramic: An
Niveen Hazem Zakaria1, Ihab A Hammad2, Yasser M Aly3
1Assistant Lecturer of Fixed Prosthodontics, Department of Conservative Dentistry, Faculty of Dentistry, Alexandria University, Alexandria, Egypt.
Statement Of Problem:
Pattern materials and their fabrication techniques have been reported to affect the marginal accuracy and internal fit of pressed lithium disilicate ceramic restorations. However, information regarding their effect on the color of such restorations is lacking.
Purpose:
The purpose of this in vitro study was to evaluate the color of a pressed lithium disilicate glass-ceramic fabricated from wax or resin patterns by using conventional and milling techniques.
Material And Methods:
Fifty-six Ø14×1.5-mm disk pattern specimens were divided into 4 groups based on the pattern material and fabrication technique: conventional wax pattern group (CW), conventional resin pattern group (CR), milled wax pattern group (MW), and milled resin pattern group (MR). Lithium disilicate specimens were fabricated by using the lost wax technique. The CIELab values were measured with a spectrophotometer (VITA Easyshade Advance). The ΔE00 values were calculated and compared with perceptibility (ΔE00=0.8) and acceptability (ΔE00=1.8) thresholds to interpret the color differences. The 2-way ANOVA and Tukey post hoc tests were used to analyze data (α=.05).
Results:
Two-way ANOVA revealed that ΔE00 was significantly affected by the pattern material (P<.001), fabrication technique (P=.034), and their interaction (P<.001). The ΔE00 of the CW group (0.76 ±0.04) was clinically imperceptible. No significant difference in the ΔE00 values was found between the reference and the MW (1.48 ±0.13) and MR (1.51 ±0.15) groups (P=.926), which were both clinically perceptible and acceptable. The highest ΔE00 was that of the CR group (2.06 ±0.22).
Conclusions:
The color of the pressed lithium disilicate ceramic was influenced by the wax and resin pattern materials fabricated by using conventional or computer-aided design and computer-aided manufacturing (CAD-CAM) techniques. Only the CW pattern group showed color differences below the clinically perceptible threshold (ΔE00=0.8). The CR pattern group showed the highest color differences, which were not clinically acceptable.
