MSciD Graduate Program, School of Dentistry, Meridional Faculty - IMED, Passo Fundo, Rio Grande do Sul State, Brazil.
MSciD and PhD Post-Graduate Program in Oral Science (Prosthodontics Units), Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul State, Brazil.
J Mech Behav Biomed Mater. 2019 Jun;94:144-154. doi: 10.1016/j.jmbbm.2019.03.005. Epub 2019 Mar 9.
To evaluate the fatigue failure load (FFL), number of cycles for failure (CFF) and survival probabilities of lithium-disilicate (LD) monolithic crowns manufactured by two processing techniques (pressing vs. CAD/CAM) adhesively cemented to a dentin-analogue material, considering two surface treatments (conventional vs. simplified). Surface characteristics (topography, roughness and fractal dimensions) were also assessed. Forty (40) monolithic crowns were manufactured considering two specific processing techniques for each ceramic system: LD - CAD/CAM lithium-disilicate (IPS e.max CAD, Ivoclar Vivadent); LD - pressed lithium-disilicate (IPS e.max Press, Ivoclar Vivadent). The crowns were adhesively cemented (Multilink Automix System, Ivoclar Vivadent) onto dentin analogue preparations considering two distinct protocols of surface treatments (conventional - hydrofluoric acid etching + silane application [HF+Sil] or simplified - etching with one-step primer (Monobond Etch&Prime, Ivoclar Vivadent) [EP]). The cemented assembly was stored in distilled water at 37 °C for 3 days and fatigue tests were run (step-stress approach: load ranging from 400 to 2000 N, step-size of 100 N, 15,000 cycles/step, 20 Hz). Fractography, surface topography, roughness, and fractal dimension analyses were performed. LD[EP] group depicted higher FFL, CFF and survival probabilities in comparison to LD groups, regardless of the conditioning method. A tendency of higher Weibull modulus (mechanical reliability) was observed when using [EP] for both LD and LD. SEM and AFM analysis showed very distinct initial surface patterns for the distinct processing techniques considered (LD with higher fractal dimension and lower roughness than LD), and both surface treatments distinctly affected these surface characteristics. All failures were radial cracks originating at the ceramic-cement interface. Pressed lithium-disilicate monolithic crowns showed better fatigue performance in comparison to CAD/CAM milled crowns, especially when they were treated with self-etching ceramic primer. The surface treatment with self-etching primer led to similar fatigue performance when compared to hydrofluoric acid plus silane application for the same processing technique, but it tended to provide higher mechanical reliability.
为了评估两种加工技术（压制与 CAD/CAM）制造的锂硅玻璃（LD）整体冠的疲劳失效载荷（FFL）、失效循环数（CFF）和存活率，并考虑两种表面处理方法（常规处理与简化处理），我们将整体冠用黏结剂黏接到类似牙本质的材料上。同时还评估了表面特性（形貌、粗糙度和分形维数）。对于每个陶瓷系统，都考虑了两种特定的加工技术来制造 40 个整体冠：LD-CAD/CAM 锂硅玻璃（IPS e.max CAD，义获嘉伟瓦登特）和 LD-压制锂硅玻璃（IPS e.max Press，义获嘉伟瓦登特）。根据两种不同的表面处理方案（常规处理-氢氟酸蚀刻+硅烷应用[HF+Sil]或简化处理-一步底漆蚀刻[Monobond Etch&Prime，义获嘉伟瓦登特] [EP]），将 Crowns 黏接到类似牙本质的预备体上。黏合组件在 37°C 的蒸馏水中储存 3 天，然后进行疲劳测试（阶跃应力方法：负载范围为 400 至 2000N，阶跃大小为 100N，每步 15000 次循环，20Hz）。进行了断口形貌、表面形貌、粗糙度和分形维数分析。与 LD 组相比，无论处理方法如何，LD[EP]组的 FFL、CFF 和存活率都更高。当对 LD 和 LD 均使用[EP]时，观察到更高的韦布尔模数（机械可靠性）的趋势。SEM 和 AFM 分析显示，对于所考虑的不同加工技术，初始表面模式非常不同（LD 的分形维数更高，粗糙度更低），两种表面处理方法都明显影响了这些表面特性。所有失效均为起源于陶瓷-黏结剂界面的放射状裂纹。与 CAD/CAM 铣削冠相比，压制的锂硅玻璃整体冠显示出更好的疲劳性能，尤其是当它们用自酸蚀陶瓷底漆处理时。与氢氟酸加硅烷处理相比，用自酸蚀陶瓷底漆处理对于相同的加工技术可导致相似的疲劳性能，但倾向于提供更高的机械可靠性。
