Int J Periodontics Restorative Dent. 2022 Jul-Aug;42(4):459-469. doi: 10.11607/prd.5736.
This study evaluates the fatigue resistance and failure mode of CAD/CAM composite resin and lithium disilicate-bonded screw-retained incisor crowns with long and short titanium bases. Sixty CAD/CAM implant restorations were fabricated using lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) and composite resin (Block HC, Shofu). The central incisor crowns were bonded to a prefabricated titanium base 6 mm tall (groups: Emax6 and Shofu6; n = 15 each) or a modified abutment 4 mm tall (groups: Emax4 and Shofu4; n = 15 each). The intaglio surface of the restorations was conditioned according to the material and bonded to the titanium abutments/bases using dual-cure cement. All assembled crowns were torqued onto implants and subjected to cyclic isometric loading at the incisal edge along the implant axis. Samples were loaded until fracture. Groups were compared using Kaplan-Meier survival analysis (log rank test at P = .05). The number of mean survived cycles differed significantly, with Emax6 and Emax4 at 48,448 and 43,727 cycles, respectively, and Shofu6 and Shofu4 at 44,124 and 37,620 cycles, respectively. Post hoc tests showed similar fatigue resistance for Emax6, Emax4, and Shofu6. Shofu4 was less resistant than all other groups (P < .03). All restorations survived significantly above physiologic load limits. Lithium disilicate screw-retained incisor crowns can be used with long and short titanium bases, while it is recommended to keep a long titanium base for screw-retained composite resin crowns. The composite resin material required the full height of the abutment for optimal strength but may offer enhanced shock absorption and wear-friendliness when considering function and antagonistic wear.
本研究评估了长、短钛基 CAD/CAM 复合树脂和锂硅玻璃陶瓷粘结螺丝固位前牙冠的耐疲劳性和失效模式。使用锂硅玻璃陶瓷（IPS e.max CAD，Ivoclar Vivadent）和复合树脂（Block HC，Shofu）制作了 60 个 CAD/CAM 种植体修复体。中央前牙冠用 6mm 高的预制钛基底（Emax6 和 Shofu6 组，每组 15 个）或 4mm 高的改良基台（Emax4 和 Shofu4 组，每组 15 个）粘结。根据材料对修复体的凹面进行处理，并用双固化水泥粘结到钛基台/基底上。所有组装好的冠均拧到种植体上，并沿种植体轴在切缘处进行等距循环加载。样品加载至断裂。使用 Kaplan-Meier 生存分析（P =.05 时对数秩检验）比较各组。平均存活循环数差异有统计学意义，Emax6 和 Emax4 分别为 48448 和 43727 次，Shofu6 和 Shofu4 分别为 44124 和 37620 次。事后检验表明 Emax6、Emax4 和 Shofu6 的耐疲劳性相似。Shofu4 的耐疲劳性明显低于其他组（P <.03）。所有修复体的生存能力均明显高于生理负荷极限。可以使用长、短钛基台固定螺丝的锂硅玻璃陶瓷粘结前牙冠，而建议为螺丝固位复合树脂冠保留长钛基台。复合树脂材料需要基台的全高度才能达到最佳强度，但在考虑功能和对抗性磨损时，可能会提供更好的减震和耐磨损性。
