Department of Prosthodontics, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan.
Division of Dental Biomaterials, Clinic for Reconstructive Dentistry, Center of Dental Medicine, University of Zurich, Zurich, Switzerland; Clinic of Masticatory Disorders and Dental Biomaterials, Center of Dental Medicine, University of Zurich, Zurich, Switzerland; Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.
J Mech Behav Biomed Mater. 2023 Dec;148:106184. doi: 10.1016/j.jmbbm.2023.106184. Epub 2023 Oct 10.
This study investigated the impact of preparation design and material types on fracture strength in maxillary premolars endocrowns after thermodynamic aging.
Eighty two-rooted maxillary premolar crowns underwent endodontic treatment (N = 80, n = 10). The teeth were categorized into ten groups (4-mm deep with no intracanal extension lithium disilicate glass ceramic & multilayer zirconia endocrowns (LE0 & ZE0); 4-mm deep with 4-mm intracanal extension in one canal (LE1 & ZE1); 4-mm deep with 2-mm intracanal extensions in both canals (LE2 & ZE2); flat overlays with no endocore (LO & ZO); glass fiber reinforced post & core and crown (LC & ZC)). After cementation, all specimens were subjected to 1500 thermocycles and 1,200,000 chewing cycles with an axial occlusal load of 49 N. A static loading test was performed at a non-axial 45° loading using a universal testing machine and failure modes (Type I: restoration debonding; Type II: restoration fracture; Type III: restoration/tooth complex fracture above bone level; Type IV: restoration/tooth complex fracture below bone level) were evaluated using a stereoscope. Data were ananalzed using 2-way ANOVA and Tukey's tests (alpha = 0.05).
The endocrowns manufactured from multilayered zirconia and pressed lithium disilicate glass ceramic exhibited a fracture load ranging between 1334 ± 332 N and 756 ± 150 N, with ZC presenting the highest and LE2 the lowest values. The differences were not statistically significant (p > 0.05).
All endocrowns tested in this study performed similar considering the different designs and materials tested. The distribution of fracture modes did not differ significantly depending on the design of the restoration and the type of material used.
本研究调查了热力学老化后上颌前磨牙根管内冠的预备设计和材料类型对断裂强度的影响。
82 颗根上颌前磨牙牙冠进行根管治疗（N=80，n=10）。将牙齿分为 10 组（4mm 深无根管内延伸的锂硅玻璃陶瓷和多层氧化锆根管内冠（LE0 和 ZE0）；4mm 深，1 个根管内延伸 4mm（LE1 和 ZE1）；2 个根管内均延伸 2mm（LE2 和 ZE2）；无根管内核的平盖（LO 和 ZO）；玻璃纤维增强桩核和冠（LC 和 ZC））。粘固后，所有样本均在轴向咬合载荷为 49N 下经受 1500 次热循环和 120 万次咀嚼循环。使用万能试验机以非轴向 45°加载进行静态加载试验，并使用立体显微镜评估失效模式（I 型：修复体脱粘；II 型：修复体断裂；III 型：修复体/牙复合体在骨水平以上断裂；IV 型：修复体/牙复合体在骨水平以下断裂）。数据采用双因素方差分析和 Tukey 检验（α=0.05）进行分析。
由多层氧化锆和压制的锂硅玻璃陶瓷制成的根管内冠的断裂载荷在 1334±332N 和 756±150N 之间，其中 ZC 最高，LE2 最低。差异无统计学意义（p>0.05）。
本研究中测试的所有根管内冠在不同设计和测试材料方面表现出相似的性能。根据修复体的设计和使用的材料类型，断裂模式的分布没有显著差异。
