State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Changle Xi Road 145, Xi'an, 710032, Shaanxi, China.
School of Science, Xi'an University of Posts and Telecommunications, Xi'an, 710121, China.
BMC Oral Health. 2024 Sep 28;24(1):1148. doi: 10.1186/s12903-024-04933-z.
The leftover material from the heat-pressing of IPS e.max Press ceramic is often discarded, despite some laboratories exploring its potential for reuse. However, there is a lack of data on the performance of IPS e.max Press ceramic when combined with the button portions. This study investigated the impact of repeated heat-pressing on the crystal structure and flexural strength of lithium disilicate glass-ceramic (LDGC).
Specimens (N = 30, n = 10 per group) were categorized based on the number of heat-pressing cycles: G0 (control group, no heat-pressing), G1 (one cycle of heat-pressing), and G2 (two cycles of heat-pressing). The crystal structure of LDGC bars was characterized using X-ray diffraction (XRD). Flexural strength was tested, and microstructures were analyzed via scanning electron microscopy (SEM) and the ImageJ processing program. Data were analyzed using one-way analysis of variance (ANOVA), and multiple pairwise comparisons of means were performed with Tukey's post-hoc test.
G2 exhibited significantly lower flexural strength and crystallinity, as well as larger crystal size, compared to G1 and G0 (p < 0.05). Flexural strength values decreased significantly with an increased number of heat-pressing cycles.
The mechanical properties of LDGC significantly degraded after repeated heat pressing. Therefore, it is not clinically advisable to repeatedly press the lithium disilicate ingot together with the leftover material.
IPS e.max Press 陶瓷热压剩余材料通常被丢弃，尽管一些实验室正在探索其再利用的可能性。然而，关于将剩余材料与按钮部分结合使用的 IPS e.max Press 陶瓷性能的数据却很少。本研究调查了重复热压对二硅酸锂玻璃陶瓷（LDGC）晶体结构和弯曲强度的影响。
根据热压循环次数将样品（N = 30，每组 n = 10）分为三组：G0（对照组，未热压）、G1（热压一次）和 G2（热压两次）。使用 X 射线衍射（XRD）对 LDGC 棒的晶体结构进行了表征。测试了弯曲强度，并通过扫描电子显微镜（SEM）和 ImageJ 处理程序分析了微观结构。使用单因素方差分析（ANOVA）对数据进行分析，并使用 Tukey 事后检验进行了多重均值两两比较。
与 G1 和 G0 相比，G2 的弯曲强度和结晶度显著降低，晶体尺寸也更大（p < 0.05）。随着热压循环次数的增加，弯曲强度值显著降低。
重复热压后，LDGC 的力学性能明显下降。因此，临床上不建议将锂二硅氧烷锭与剩余材料反复压制在一起。
