Gamal Nouran, Nouh Ingy, Eldemellawy Mohamed, El-Etreby Amr
Department of Fixed Prosthodontics, Faculty of Dentistry, MSA University, Cairo, Egypt.
Department of Fixed Prosthodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
BMC Oral Health. 2025 Jul 11;25(1):1146. doi: 10.1186/s12903-025-06518-w.
Ceramists often deviate from the standard crystallization temperatures and holding times recommended by manufacturers, but the effects of these variations remain unclear. The aim of this in-vitro study was to evaluate the effect of different crystallization temperatures and holding times on the color reproduction, translucency and biaxial flexural strength (BFS) of novel lithium disilicate glass ceramic (Amber Mill). In addition, microstructural changes resulting from these altered firing conditions were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).
Fifty-six Amber Mill ceramic discs (n = 56) of 12 mm diameter and 1 mm thickness in shade A2 were prepared and divided into two main groups according to the final crystallization temperature (n = 28); Group (CT1): the manufacturer recommended crystallization temperature 825 °C and Group (CT2): the suggested crystallization temperature 800 °C. Each group was further subdivided into four subgroups according to the holding time (n = 7); subgroup (H1): 15 min (as recommended by the manufacturer) and other suggested holding times, subgroup (H2): 20 min, subgroup (H3): 25 min and subgroup (H4): 30 min. Color reproduction and translucency were measured using a spectrophotometer. Color differences (ΔE) and relative translucency parameter (RTP) values were calculated. BFS was measured using Piston-on-three ball test. Crystalline structure and microstructural features present in the material were described using XRD and SEM. Two-way ANOVA followed by Tukey's post hoc test at significance level of p < 0.05 was perfomed.
Decreasing crystallization temperature decreased color change and decreased translucency of Amber Mill with no influence on flexural strength. Increasing holding time led to decrease in color change with no effect on translucency and flexural strength of Amber Mill.
The Crystallization temperature suggested in this study showed superior results in terms of color change when compared to the manufacturer's recommendations, with reduced translucency and no significant impact on the flexural strength of Amber Mill. Suggested holding times decreased color change without affecting either translucency or flexural strength of Amber Mill.
陶艺家常常偏离制造商推荐的标准晶化温度和保温时间，但其影响尚不清楚。本体外研究旨在评估不同晶化温度和保温时间对新型二硅酸锂玻璃陶瓷（琥珀磨盘）颜色再现、半透明度和双轴弯曲强度（BFS）的影响。此外，使用X射线衍射（XRD）和扫描电子显微镜（SEM）分析这些改变的烧制条件导致的微观结构变化。
制备56个直径12mm、厚度1mm、色号为A2的琥珀磨盘陶瓷圆盘（n = 56），并根据最终晶化温度分为两个主要组（n = 28）；组（CT1）：制造商推荐的晶化温度825°C，组（CT2）：建议的晶化温度800°C。每组再根据保温时间分为四个亚组（n = 7）；亚组（H1）：15分钟（如制造商推荐）和其他建议的保温时间，亚组（H2）：20分钟，亚组（H3）：25分钟，亚组（H4）：30分钟。使用分光光度计测量颜色再现和半透明度。计算颜色差异（ΔE）和相对半透明度参数（RTP）值。使用三球顶活塞试验测量BFS。使用XRD和SEM描述材料中存在的晶体结构和微观结构特征。进行双向方差分析，随后进行Tukey事后检验，显著性水平为p < 0.05。
降低晶化温度可减少琥珀磨盘的颜色变化并降低半透明度，而对弯曲强度无影响。增加保温时间可减少颜色变化，对琥珀磨盘的半透明度和弯曲强度无影响。
与制造商的建议相比，本研究中建议的晶化温度在颜色变化方面显示出更好的结果，半透明度降低，对琥珀磨盘的弯曲强度无显著影响。建议的保温时间减少了颜色变化，而不影响琥珀磨盘的半透明度或弯曲强度。
