Sawangsri Kedith, Makowka Steven, Bencharit Sompop, Kim Hyeongil
Division of Restorative and Prosthetic Dentistry, College of Dentistry, The Ohio State University, Columbus, Ohio, USA.
Material testing facility, School of Dental Medicine, University at Buffalo, State University of New York, Buffalo, New York, USA.
J Prosthodont. 2024 Sep 27. doi: 10.1111/jopr.13956.
A newly introduced sintering protocol promises to offer higher translucency while not significantly compromising the flexural strength of the material. However, the effect of the novel sintering protocol has not been thoroughly validated. The purpose of this study was to measure and compare the effect of two sintering protocols on the translucency and flexural strength of two multilayered zirconia materials.
Two types of multilayered zirconia materials (ZirCAD Prime and Prime esthetic) were selected. Presintered disk specimens were obtained from Translucent, Gradient, and Dentin layers (n = 20). The disks were allocated to 2 groups: standard sintering protocol (peak temperature 1500°C) and high translucency sintering protocol (peak temperature 1600°C). After the sintering process, 10 specimens from each group were randomly selected. The optical values (L, a, b) were measured and used to assess translucency using the relative translucency parameter (RTP) and translucency differences (ΔRTP). Then, all 20 specimens were tested for biaxial flexural strength. The outcomes were analyzed. The analysis of variance is used to analyze any significant effects on translucency and flexural strength. Then, any significant difference in the translucency and flexural strength between all pairs of materials was analyzed using Bonferroni-corrected Student's t-test (α = 0.05).
The high translucency sintering protocol significantly decreased biaxial strength in the Prime translucent and dentine layer, Prime esthetic translucent, and gradient layer. RTP was significantly reduced in the Prime gradient and Prime esthetic gradient layer when sintered with a high translucency protocol. The lowest ΔRTP was observed in the Prime dentine layer, while the highest ΔRTP was observed in the Prime esthetic dentin layer.
High translucency protocol significantly lowers the biaxial flexural strength of both multilayered materials, but the alteration in translucency is within clinically acceptable thresholds (TAT = 2.62).
一种新引入的烧结方案有望在不显著降低材料抗弯强度的情况下提供更高的透明度。然而，这种新型烧结方案的效果尚未得到充分验证。本研究的目的是测量并比较两种烧结方案对两种多层氧化锆材料的透明度和抗弯强度的影响。
选择两种类型的多层氧化锆材料（ZirCAD Prime和Prime esthetic）。从半透明层、渐变层和牙本质层获取预烧结圆盘试件（n = 20）。将圆盘分为两组：标准烧结方案（峰值温度1500°C）和高透明度烧结方案（峰值温度1600°C）。烧结过程完成后，从每组中随机选取10个试件。测量光学值（L、a、b），并使用相对透明度参数（RTP）和透明度差异（ΔRTP）来评估透明度。然后，对所有20个试件进行双轴抗弯强度测试。对结果进行分析。采用方差分析来分析对透明度和抗弯强度的任何显著影响。然后，使用Bonferroni校正的学生t检验（α = 0.05）分析所有材料对之间透明度和抗弯强度的任何显著差异。
高透明度烧结方案显著降低了Prime半透明和牙本质层、Prime esthetic半透明层和渐变层的双轴强度。当采用高透明度方案烧结时，Prime渐变层和Prime esthetic渐变层的RTP显著降低。在Prime牙本质层观察到最低的ΔRTP，而在Prime esthetic牙本质层观察到最高的ΔRTP。
高透明度方案显著降低了两种多层材料的双轴抗弯强度，但透明度的改变在临床可接受阈值范围内（TAT = 2.62）。
