Zamzam Hadiel, Olivares Antonio, Fok Alex
Prosthodontic Department, National Research Center, Dokki, 12622, Cairo, Egypt.
Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, 16-212 Moos Health Science Tower, 515 Delaware Street S.E., Minneapolis, MN, 55455, USA.
J Mech Behav Biomed Mater. 2021 Mar;115:104290. doi: 10.1016/j.jmbbm.2020.104290. Epub 2021 Jan 6.
The aim of this in vitro study was to analyze the failure of occlusal veneers made of three different restorative CAD/CAM materials under lateral static loading.
Sixty standardized semi-anatomical occlusal veneers were fabricated on natural lower molars from three different CAD/CAM materials: hybrid ceramic (Vita Enamic), lithium disilicate (IPS e. max CAD) and translucent zirconia (Bruxzir). The specimens were mechanically loaded by a custom-made device attached to a universal testing machine (MTS 858 Mini Bionix II, MN, USA). Static lateral loading was applied on the buccal cusp of the occlusal veneer until failure. Failure loads were recorded, and the types of failure noted for each group. 3D finite element (FE) models simulating the actual test set-up were further employed to evaluate the stresses within the tooth-restoration complex to help interpret the experimental results.
Occlusal veneers made from zirconia recorded a significantly higher mean failure load (843.1 ± 141.5 N) than specimens of the other two materials (p < 0.05). There was no statistically significant difference between the lithium disilicate (493.21 ± 102.24 N) and the hybrid ceramic (499.6 ± 123.1 N) groups (p = 0.863). 74% of the hybrid ceramic and 84% of the lithium disilicate specimens showed veneer fracture, whereas 78% of the zirconia veneers showed debonding. Comparison of the FE-predicted stresses with the different failure strengths corroborated with the experimental results.
Lateral loading caused failure of occlusal veneers at loads significantly lower than those reported for axial loading. Among the materials tested, zirconia veneers showed the highest resistance to failure, with the main failure mode being debonding under lateral loading. The other two material groups failed mainly by veneer fracture at lower loads.
本体外研究旨在分析三种不同修复性CAD/CAM材料制成的咬合贴面在侧向静态加载下的失效情况。
用三种不同的CAD/CAM材料在天然下颌磨牙上制作60个标准化的半解剖型咬合贴面：混合陶瓷（维他易美）、二硅酸锂（义获嘉e.max CAD）和半透明氧化锆（Bruxzir）。通过连接到万能试验机（美国明尼苏达州MTS 858 Mini Bionix II）的定制装置对标本进行机械加载。在咬合贴面的颊尖施加静态侧向载荷直至失效。记录失效载荷，并记录每组的失效类型。进一步采用模拟实际测试设置的三维有限元（FE）模型来评估牙齿修复复合体内部的应力，以帮助解释实验结果。
氧化锆制成的咬合贴面记录的平均失效载荷（843.1±141.5 N）显著高于其他两种材料的标本（p<0.05）。二硅酸锂组（493.21±102.24 N）和混合陶瓷组（499.6±123.1 N）之间无统计学显著差异（p = 0.863）。74%的混合陶瓷标本和84%的二硅酸锂标本出现贴面断裂，而78%的氧化锆贴面出现脱粘。有限元预测应力与不同失效强度的比较与实验结果相符。
侧向加载导致咬合贴面在远低于轴向加载报告载荷的情况下失效。在所测试的材料中，氧化锆贴面显示出最高的抗失效性，主要失效模式是侧向加载下的脱粘。其他两组材料主要在较低载荷下因贴面断裂而失效。
