Department of Prosthetic Dentistry, Dental School, LMU Munich, Goethestraße 70, 80336, Munich, Germany.
Department of Reconstructive Dentistry and Gerodontology, University of Bern, Freiburgstrasse 7, 3007, Bern, Switzerland.
Clin Oral Investig. 2022 Nov;26(11):6617-6628. doi: 10.1007/s00784-022-04616-5. Epub 2022 Jul 15.
The aim of this study is to investigate the influence of the material and corresponding sintering protocol, layer thickness, and aging on the two-body wear (2BW) and fracture load (FL) of 4Y-TZP crowns.
Multi-layer 4Y-TZP crowns in three thicknesses (0.5 mm/1.0 mm/1.5 mm) were sintered by high-speed (Zolid RS) or conventional (Zolid Gen-X) sintering. 2BW of ceramic and enamel antagonist after aging (1,200,000 mechanical-, 6000 thermal-cycles) was determined by 3D-scanning before and after aging and subsequent matching to determine volume and height loss (6 subgroups, n = 16/subgroup). FL was examined initially and after aging (12 subgroups, n = 16/subgroup). Fractographic analyses were performed using light-microscope imaging. Global univariate analysis of variance, one-way ANOVA, linear regression, Spearman's correlation, Kolgomorov-Smirnov, Mann-Whitney U, and t test were computed (alpha = 0.05). Weibull moduli were determined. Fracture types were analyzed using Ciba Geigy table.
Material/sintering protocol did not influence 2BW (crowns: p = 0.908, antagonists: p = 0.059). High-speed sintered Zolid RS presented similar (p = 0.325-0.633) or reduced (p < 0.001-0.047) FL as Zolid Gen-X. Both 4Y-TZPs showed an increased FL with an increasing thickness (0.5(797.3-1429 N) < 1.0(2087-2634 N) < 1.5(2683-3715 N)mm; p < 0.001). For most groups, aging negatively impacted FL (p < 0.001-0.002). Five 0.5 mm specimens fractured, four showed cracks during and after aging.
High-speed sintered crowns with a minimum thickness of 1.0 mm showed sufficient mechanical properties to withstand masticatory forces, even after a simulated aging period of 5 years.
Despite the manufacturer indicating a thickness of 0.5 mm to be suitable for single crowns, a minimum thickness of 1.0 mm should be used to ensure long-term satisfactory results.
本研究旨在探讨材料及相应的烧结方案、层厚和时效对 4Y-TZP 牙冠的三体磨耗（2BW）和断裂载荷（FL）的影响。
采用高速（Zolid RS）或常规（Zolid Gen-X）烧结法对三种厚度（0.5mm/1.0mm/1.5mm）的多层 4Y-TZP 牙冠进行烧结。在时效（120 万次机械循环、6000 次热循环）前后通过 3D 扫描来确定陶瓷和釉质对牙面的 2BW，并进行后续匹配以确定体积和高度损失（6 个亚组，每组 16 个）。初始和时效后（12 个亚组，每组 16 个）分别对 FL 进行检测。使用光学显微镜成像进行断口分析。采用单变量方差分析、单因素方差分析、线性回归、Spearman 相关分析、Kolgomorov-Smirnov 检验、Mann-Whitney U 检验和 t 检验（α=0.05）。确定韦布尔模数。使用 Ciba Geigy 表分析断裂类型。
材料/烧结方案未影响 2BW（牙冠：p=0.908，牙面：p=0.059）。高速烧结的 Zolid RS 与 Zolid Gen-X 具有相似的（p=0.325-0.633）或降低的（p<0.001-0.047）FL。两种 4Y-TZP 均表现出随厚度增加而增加的 FL（0.5mm（797.3-1429N）<1.0mm（2087-2634N）<1.5mm（2683-3715N）；p<0.001）。对于大多数组，时效对 FL 有负面影响（p<0.001-0.002）。5 个 0.5mm 试件发生断裂，4 个在时效过程中和之后出现裂纹。
厚度至少为 1.0mm 的高速烧结牙冠具有足够的机械性能，可承受咀嚼力，即使在模拟 5 年老化期后也是如此。
尽管制造商表明 0.5mm 厚度适用于单冠，但为确保长期满意的效果，应使用最小厚度为 1.0mm。
