Nossair Shereen Ahmed, Aboushelib Moustafa N, Morsi Tarek Salah
Department of Fixed Prosthodontics, Future University, Cairo, Egypt.
Fixed Prosthodontics Department, Ain Shams University, Cairo, Egypt.
J Prosthodont. 2015 Oct;24(7):543-548. doi: 10.1111/jopr.12253. Epub 2015 Jan 5.
To evaluate the fracture mechanics of cemented versus fused CAD-on veneers on customized zirconia implant abutments.
Forty-five identical customized CAD/CAM zirconia implant abutments (0.5 mm thick) were prepared and seated on short titanium implant abutments (Ti base). A second scan was made to fabricate 45 CAD-on veneers (IPS Empress CAD, A2). Fifteen CAD-on veneers were cemented on the zirconia abutments (Panavia F2.0). Another 15 were fused to the zirconia abutments using low-fusing glass, while manually layered veneers served as control (n = 15). The restorations were subjected to artificial aging (3.2 million cycles between 5 and 10 kg in a water bath at 37°C) before being axially loaded to failure. Fractured specimens were examined using scanning electron microscopy to detect fracture origin, location, and size of critical crack. Stress at failure was calculated using fractography principles (alpha = 0.05).
Cemented CAD-on restorations demonstrated significantly higher (F = 72, p < 0.001) fracture load compared to fused CAD-on and manually layered restorations. Fractographic analysis of fractured specimens indicated that cemented CAD-on veneers failed due to radial cracks originating from the veneer/resin interface. Branching of the critical crack was observed in the bulk of the veneer. Fused CAD-on veneers demonstrated cohesive fracture originating at the thickest part of the veneer ceramic, while manually layered veneers failed due to interfacial fracture at the zirconia/veneer interface.
Within the limitations of this study, cemented CAD-on veneers on customized zirconia implant abutments demonstrated higher fracture than fused and manually layered veneers.
评估在定制氧化锆种植体基台上粘结式与熔附式CAD制作的贴面的断裂力学性能。
制备45个相同的定制CAD/CAM氧化锆种植体基台（厚0.5mm），并安装在短钛种植体基台上（钛基底）。进行第二次扫描以制作45个CAD制作的贴面（IPS Empress CAD，A2）。15个CAD制作的贴面粘结在氧化锆基台上（Panavia F2.0）。另外15个使用低熔点玻璃熔附到氧化锆基台上，同时手工分层贴面作为对照（n = 15）。修复体在轴向加载至破坏前进行人工老化（在37°C水浴中在5至10kg之间循环320万次）。使用扫描电子显微镜检查断裂的标本，以检测断裂起源、位置和临界裂纹的大小。使用断口分析原理计算破坏时的应力（α = 0.05）。
与熔附式CAD制作的修复体和手工分层修复体相比，粘结式CAD制作的修复体表现出显著更高（F = 72，p < 0.001）的断裂载荷。对断裂标本的断口分析表明，粘结式CAD制作的贴面因源自贴面/树脂界面的径向裂纹而失效。在贴面主体中观察到临界裂纹的分支。熔附式CAD制作的贴面表现出在贴面陶瓷最厚部分起源的内聚断裂，而手工分层贴面因氧化锆/贴面界面的界面断裂而失效。
在本研究的局限性内，定制氧化锆种植体基台上的粘结式CAD制作的贴面表现出比熔附式和手工分层贴面更高的断裂性能。
