Department of Prosthodontics, Faculty of Dentistry, Ankara University, Ankara, Turkey.
University of Zürich, Division of Dental Biomaterials, Center for Dental and Oral Medicine, Clinic for Reconstructive Dentistry, Zürich, Switzerland.
J Esthet Restor Dent. 2020 Jul;32(5):472-479. doi: 10.1111/jerd.12591. Epub 2020 May 5.
The purpose of this in vitro study was to compare the effect of simulated endodontic access preparation on the failure loads of lithium disilicate crowns and resin-matrix ceramic (RMC) crowns.
Eighty maxillary first premolar crowns were manufactured by using four different CAD/CAM blocks (n = 20): lithium disilicate (LD; IPS e.max CAD), resin nanoceramic (RNC; Lava Ultimate), flexible nanaoceramic (FNC; GC Cerasmart), and polymer-infiltrated ceramic (PIC; VITA Enamic). Half of each group was accessed and repaired to simulate endodontic treatment. After cyclic loading, all specimens were loaded to failure. Data were analyzed with two-way ANOVA followed by Tukey-HSD test (α = .05).
The load to failure results showed significant differences for material types (P < .001), but not for endodontic access simulation (P = .09). The highest and lowest mean failure loads were obtained for LD (1546 N) and PIC (843 N), respectively.
The endodontic access preparation was not found to affect the fracture strength of LD and RMC crowns. The LD showed higher fracture strength than RMC crowns. Even though significant differences were noted for failure loads regarding different crown materials, all could reasonably withstand masticatory forces.
The endodontic access preparation through a restoration is known to be a common challenge in clinical practice. Maintaining a repaired LD or RMC crown is feasible and replacement may not be necessary.
本体外研究的目的是比较模拟根管治疗入口预备对锂硅玻璃陶瓷冠和树脂基质陶瓷（RMC）冠失败负荷的影响。
使用 4 种不同的 CAD/CAM 块（n = 20）制造 80 个上颌第一前磨牙冠：锂硅玻璃陶瓷（LD；IPS e.max CAD）、树脂纳米陶瓷（RNC；Lava Ultimate）、柔性纳米陶瓷（FNC；GC Cerasmart）和聚合物渗透陶瓷（PIC；VITA Enamic）。每组的一半进行根管治疗模拟入口预备和修复。经过循环加载后，所有样本均加载至失效。使用双向方差分析（ANOVA）和 Tukey-HSD 检验（α =.05）对数据进行分析。
失效负荷结果显示材料类型有显著差异（P < .001），但根管治疗入口模拟无显著差异（P =.09）。LD（1546 N）和 PIC（843 N）的平均失效负荷最高和最低。
根管治疗入口预备不会影响 LD 和 RMC 冠的断裂强度。LD 的断裂强度高于 RMC 冠。尽管不同冠材料的失效负荷存在显著差异，但所有材料均能合理承受咀嚼力。
通过修复体进行根管治疗入口预备是临床实践中的常见挑战。维护修复后的 LD 或 RMC 冠是可行的，不一定需要更换。
