Dalla-Nora F, Da Rosa L S, Pereira G K R, Valandro L F, Rippe M P
MSciD and PhD Post-Graduate Program in Oral Science [Prosthodontics Units], Faculty of Dentistry, Federal University of Santa Maria [UFSM], Avenue Roraima 1000, Building 26F, room 2383, Zip Code: 97105-900, Santa Maria, Rio Grande do Sul State, Brazil.
J Mech Behav Biomed Mater. 2024 Feb;150:106312. doi: 10.1016/j.jmbbm.2023.106312. Epub 2023 Dec 11.
This study aimed to compare the fatigue performance of a lithium disilicate ceramic cemented on different substrates (human dentin and glass fiber-reinforced epoxy resin - GFRER), treated with different types of conditioning (CTR - without surface conditioning; HF5 - 5% hydrofluoric acid; HF10 - 10% hydrofluoric acid; H3PO4 - phosphoric acid 37%; SAND - sandblasting with aluminum oxide). The occlusal surface of human molars (DENT group) (n = 15) was ground for dentin exposure and the root portion was cut, then the dentin slice (2.0 mm thick) was conditioned with 37% phosphoric acid and a dual-curing dental adhesive was applied. The GFRER in a round-rod format was cut into discs (Ø = 10 mm, 2.0 mm thick). Lithium disilicate glass ceramic blocks (IPS e.max CAD, Ivoclar, Schaan, Liechtenstein) were shaped into a cylinder format and cut, resulting in 90 discs (Ø = 10 mm, 1.5 mm thick). The substrate materials of each group were etched according to the groups and the ceramic was etched with 5% hydrofluoric acid for 30 s. A silane coupling agent was applied over the cementation surface in ceramic and GFRER surfaces and a dual cement was used for cementation (ceramic/GFRER or dentin). The disc/disc sets were submitted to thermocycling (25,000 cycles + storage for 6 months), and then tested in step-wise accelerated cyclic fatigue test. The failure pattern and topography were analyzed and the roughness and contact angle were measured before and after surface treatment. The DENT group presented the lowest load to failure values and number of cycles to failure in fatigue (637.33 N; 118.333), showing no statistical similarity with any of the other tested groups (p < 0.05). The topographic analysis showed that all proposed surface treatments modified the substrate surface when compared to the CTR group. All of the fractographical inspections demonstrated failure by radial crack. Considering the roughness analysis, the post-etched DENT group showed similar roughness to all groups of GFRER materials with their surface treated, except for SAND, which showed greater roughness and statistically different from the other groups. The DENT group (49.5) showed statistically different post-conditioning contact angle values from the HF10 group (96.5) and similar to the other groups. The glass fiber-reinforced epoxy resin was not able to simulate the results presented by the human dentin substrate when cemented to lithium disilicate regarding fatigue failure load and number of cycles for failure, regardless of the surface treatment. Lithium disilicate cemented on dentin analogue overestimates the load values for fatigue failure.
本研究旨在比较不同基底（人牙本质和玻璃纤维增强环氧树脂-GFRER）上的锂硅玻璃陶瓷的疲劳性能，并对不同的处理方式（CTR-无表面处理；HF5-5%氢氟酸；HF10-10%氢氟酸；H3PO4-37%磷酸；SAND-氧化铝喷砂）进行比较。对人类磨牙的咬合面（DENT 组）（n=15）进行研磨以暴露牙本质，并切割牙根部分，然后用 37%磷酸处理牙本质片（2.0mm 厚），并应用双固化牙科粘合剂。将 GFRER 切成圆盘（Ø=10mm，2.0mm 厚）。将锂硅玻璃陶瓷块（IPS e.max CAD，Ivoclar，沙安，列支敦士登）制成圆柱形并切割，得到 90 个圆盘（Ø=10mm，1.5mm 厚）。根据组别对各组基底材料进行酸蚀，并用 5%氢氟酸对陶瓷进行酸蚀 30 秒。在陶瓷和 GFRER 表面涂覆硅烷偶联剂，并使用双水泥进行粘结（陶瓷/GFRER 或牙本质）。将圆盘/圆盘组进行热循环（25000 次循环+储存 6 个月），然后进行逐步加速循环疲劳试验。分析失效模式和形貌，测量表面处理前后的粗糙度和接触角。DENT 组的失效载荷和疲劳失效循环次数最低（637.33N；118.333），与其他测试组均无统计学相似性（p<0.05）。形貌分析表明，与 CTR 组相比，所有建议的表面处理均改变了基底表面。所有的断口分析均显示为径向裂纹失效。考虑到粗糙度分析，经酸蚀处理后的 DENT 组与经过表面处理的所有 GFRER 材料组的粗糙度相似，除了 SAND 组，其粗糙度较大，与其他组有统计学差异。DENT 组（49.5）的后处理接触角值与 HF10 组（96.5）有统计学差异，与其他组相似。玻璃纤维增强环氧树脂在与锂硅玻璃陶瓷粘结时，无论表面处理如何，都无法模拟人牙本质基底的疲劳失效载荷和失效循环次数。在牙本质模拟物上粘结的锂硅玻璃陶瓷高估了疲劳失效的载荷值。
