Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos, São Paulo, Brazil.
Graduate Program in Dentistry, Federal University of Pelotas (UFPel), Pelotas, Rio Grande do Sul, Brazil.
J Prosthodont. 2024 Apr;33(4):389-395. doi: 10.1111/jopr.13705. Epub 2023 Jun 5.
This study evaluated the fatigue failure load (FFL) and the number of cycles for fatigue failure (CFF) of traditional (porcelain layer up) and reversed (zirconia layer up) designs of porcelain-veneered zirconia samples prepared with heat-pressing or file-splitting techniques.
Zirconia discs were prepared and veneered with heat-pressed or machined feldspathic ceramic. The bilayer discs were bonded onto a dentin-analog according to the bilayer technique and sample design: traditional heat-pressing (T-HP), reversed heat-pressing (R-HP), traditional file-splitting with fusion ceramic (T-FC), reversed file-splitting with fusion ceramic R-FC), traditional file-splitting with resin cement (T-RC), and reversed file-splitting with resin cement (R-RC). The fatigue tests were performed using the stepwise approach at 20 Hz, 10,000 cycles/step, step-size of 200 N starting at 600 N, and proceeding until failure detection or up to 2600 N if enduring. The failure modes (from radial and/or cone cracks) were analyzed in a stereomicroscope.
The reversed design decreased the FFL and CFF of bilayers prepared with heat-pressing and file-splitting with fusion ceramic. The T-HP and T-FC reached the highest results, which were statistically similar between them. The bilayers prepared by the file-splitting with resin cement (T-RC and R-RC) were similar to the R-FC and R-HP groups regarding FFL and CFF. Almost all reverse layering samples failed by radial cracks.
The reverse layering design did not improve the fatigue behavior of porcelain veneered zirconia samples. The three bilayer techniques behaved similarly when used in the reversed design.
本研究评估了传统（瓷层在上）和反转（氧化锆层在上）设计的热压或分切技术制备的烤瓷氧化锆样本的疲劳失效负荷（FFL）和疲劳失效循环数（CFF）。
制备氧化锆圆盘并用热压或机械加工的长石质陶瓷贴面。双层圆盘根据双层技术和样本设计粘结到牙本质模拟体上：传统热压（T-HP）、反转热压（R-HP）、传统熔附陶瓷分切（T-FC）、反转熔附陶瓷分切（R-FC）、传统树脂粘结剂分切（T-RC）和反转树脂粘结剂分切（R-RC）。疲劳试验采用逐步法在 20Hz、10000 次/步、600N 起始、200N 步长的条件下进行，直至失效检测或达到 2600N 为止，如果能耐受的话。在立体显微镜下分析失效模式（来自放射状和/或锥形裂纹）。
反转设计降低了热压和熔附陶瓷分切制备的双层的 FFL 和 CFF。T-HP 和 T-FC 达到了最高的结果，它们之间在统计学上是相似的。用树脂粘结剂分切制备的双层（T-RC 和 R-RC）在 FFL 和 CFF 方面与 R-FC 和 R-HP 组相似。几乎所有反转分层样本都因放射状裂纹而失效。
反转分层设计并没有改善烤瓷氧化锆样本的疲劳性能。当在反转设计中使用时，三种双层技术表现相似。
