Rizkallah Nadine I, Abdelfatah Ghada, Wahsh Marwa M, Abdel Sadek Hoda M
Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
Faculty of Dentistry, Ain Shams University, Organization of African Unity St, El-Qobba Bridge, El Weili, Cairo, Egypt.
BMC Oral Health. 2025 May 5;25(1):685. doi: 10.1186/s12903-025-06011-4.
The repeated firings can enhance shade matching, translucency, and strength; however, they may also lead to color shifts. Previous research suggests that multiple firings enhance these properties to a certain extent; however, the impact of staining techniques remains underexplored. The aim of this study is to investigate the effect of staining techniques and multiple firings on the translucency, color and biaxial flexural strength of advanced lithium disilicate ALD containing Virgilite crystals.
Sixty-three discs of ALD (CEREC Tessera) were divided into 3 groups based on staining techniques (n = 21); group CO (glaze only), group SC (single-step characterization), and group DC (double-step characterization). The discs were then subjected to either 2, 4, or 6 firing cycles, resulting in 9 groups (n = 7): COII, COIV, COVI, SCII, SCVI, DCII, DCIV, and DCVI. Relative translucency parameter (RTP), color change (ΔE), and biaxial flexural strength were measured, then discs were analyzed using SEM. Data were statistically analyzed using ANOVA, Bonferroni correction, and Spearman's correlation (α = 0.05).
Repeated firing and staining techniques significantly affected translucency, color change, and biaxial flexural strength (p < 0.001). Translucency increased with firings, highest in CO and lowest in DC. ΔE increased with firings, highest for DC and lowest in CO. The biaxial flexural strength of the CO group remained stable across firing cycles, with no significant changes. The SC group, initially the weakest, showed a significant increase, reaching its peak after six cycles. The DC group had high strength in the fourth cycle, with a significant difference observed between the second and fourth cycles. By the sixth cycle, all groups showed comparable strength with no significant differences.
Within the limitation of this study, firing cycles and staining techniques impact the properties of ALD. More firing cycles enhance translucency but increase color change. Repeated firing, particularly with the double-step characterization technique, significantly improved biaxial flexural strength up to the fourth cycle, demonstrating its superior performance over the single-step characterization technique.
多次烧制可增强色泽匹配度、半透明度和强度；然而，它们也可能导致颜色变化。先前的研究表明，多次烧制在一定程度上可增强这些特性；然而，染色技术的影响仍未得到充分探索。本研究的目的是调查染色技术和多次烧制对含维里石晶体的先进二硅酸锂（ALD）的半透明度、颜色和双轴弯曲强度的影响。
将63个ALD（CEREC Tessera）圆盘根据染色技术分为3组（n = 21）；CO组（仅釉料）、SC组（单步表征）和DC组（双步表征）。然后将圆盘进行2、4或6次烧制循环，得到9组（n = 7）：COII、COIV、COVI、SCII、SCVI、DCII、DCIV和DCVI。测量相对半透明度参数（RTP）、颜色变化（ΔE）和双轴弯曲强度，然后使用扫描电子显微镜对圆盘进行分析。数据采用方差分析、Bonferroni校正和Spearman相关性进行统计分析（α = 0.05）。
多次烧制和染色技术显著影响半透明度、颜色变化和双轴弯曲强度（p < 0.001）。半透明度随烧制次数增加，在CO组中最高，在DC组中最低。ΔE随烧制次数增加，在DC组中最高，在CO组中最低。CO组的双轴弯曲强度在烧制循环中保持稳定，无显著变化。SC组最初最弱，显示出显著增加，在六个循环后达到峰值。DC组在第四个循环中强度较高，在第二个和第四个循环之间观察到显著差异。到第六个循环时，所有组的强度相当，无显著差异。
在本研究的局限性内，烧制循环和染色技术会影响ALD的性能。更多的烧制循环可增强半透明度但增加颜色变化。多次烧制，特别是采用双步表征技术，在第四个循环之前显著提高了双轴弯曲强度，表明其性能优于单步表征技术。
