The effect of repeating firing cycle on the shade of porcelain fused to metal, all-ceramic and zircona restorations

Background Ceramic have a long history in fixed prosthodontics for achieving optimal esthetics and various materials have been used to improve ceramic color. However, there is a lack of information on how color is affected by fabrication procedures. Purpose The purpose of this study was to evaluate the effects of repeating firings cycle on the color of porcelain fused to metal (PFM), Empress II and Zirconium based restoration. Materials and methods Thirty disc-shaped of 10 mm in width and 1.5 mm in thickness divided into three groups (n = 10) shade A3, were fabricated each groups of PFM, Empress and Zirconia respectively. Repeated firings were performed for the specimens and color differences (ΔE) were determined using a spectrophotometer, repeated measures analysis of variance was used to analyze the data (number of firings, color). The Tukey's post-hoc test was used for pair-wise. Comparisons between the groups when analysis of variance test is significant. Results The repeated firing cycles on the ceramic discs has resulted in, Empress II showed the highest decrease in L* value with Empress II followed by zirconia and PFM showed the lowest decreased in L* value. Empress and zirconia both showed the statically significantly highest mean (Δa) values. PFM showed the statistically significantly lowest mean (Δa) Empress showed the statistically significantly highest mean (Δb). There was no statistically significantly lowest mean (Δb) value. Empress showed the statistically significantly highest mean (ΔE). Zirconia showed statistically significantly lower mean (ΔE). PFM showed the statistically significantly lowest mean (ΔE). Conclusion Empress II was highly affected by repeated firing than zirconia-based restoration, and PFM.