Hassouneh Layla, Jum'ah Ahmad A, Ferrari Marco, Wood David J
University of Leeds, School of Dentistry, Division of Restorative Dentistry, Leeds LS2 9JT, United Kingdom.
Jordan University of Science and Technology, Faculty of Dentistry, Department of Conservative Dentistry, P.O Box 3030, Irbid 22110, Jordan.
J Dent. 2020 Sep;100:103426. doi: 10.1016/j.jdent.2020.103426. Epub 2020 Jul 3.
To evaluate the post-fatigue load-to-failure and failure modes of endodontically treated premolar teeth restored with endocrowns fabricated from different CAD/CAM materials.
A total of 60 extracted human, single-rooted premolar teeth were endodontically treated and sectioned horizontally 2 mm above the cementoenamel junction. Sectioned teeth were restored using two reconstruction designs: endocrowns (C) or post-crowns (C) (n = 30 p/g). In each group, reconstructions were fabricated from 3 different CAD/CAM substrates (n = 10 p/g); a resin-based composite (Cera), a lithium disilicate glass ceramic (LiSi) and a monolithic, translucent zirconia (Zir). Additional 10 intact teeth were used as control. Restored teeth were subjected to dynamic fatigue test (10-50 N, 600,000 cycles) and thermocycling (5-55 °C, 1500 cycles). Load-to-failure and failure mode was determined following application of a static, 45° oblique compressive load on each specimen. One-way and Two-way analysis of variance (ANOVA), Tukey's post hoc and chi-square tests were used to determine statistically significant interactions among experimental and control groups.
All specimens survived the mechanical and thermal fatigue tests. A statistically significant interaction between reconstruction design and material type was observed (p < 0.001). CZir and CCera groups exhibited significantly higher post-fatigue load-to-failure when compared to other materials of the same reconstruction design (p ≤ 0.001). The highest frequency of catastrophic failures was observed with Zir reconstructions in both designs. Intact teeth exhibited significantly higher load-to-failure when compared to all groups (p ≤ 0.042) except CZir (p = 0.345).
Single piece, CAD/CAM resin composite endocrowns can present a reliable option for restoring endodontically treated premolar teeth.
Endocrowns can be as effective as post-crowns provided appropriate preparation; material selection; and bonding protocols are utilized. Clinicians need to be cautious when prescribing zirconia endocrowns to restore premolar teeth owing to the low fracture resistance and high risk of catastrophic failures.
评估用不同CAD/CAM材料制作的嵌体冠修复的根管治疗前磨牙在疲劳后直至失效的负荷及失效模式。
总共60颗拔除的人单根前磨牙进行根管治疗，并在牙骨质釉质界上方2毫米处水平切片。切片后的牙齿采用两种修复设计进行修复：嵌体冠（C）或桩冠（C）（每组30颗）。在每组中，修复体由3种不同的CAD/CAM基底材料制作（每组10颗）；一种树脂基复合材料（Cera）、一种二硅酸锂玻璃陶瓷（LiSi）和一种整体式半透明氧化锆（Zir）。另外10颗完整牙齿用作对照。修复后的牙齿进行动态疲劳试验（10 - 50 N，600,000次循环）和热循环试验（5 - 55°C，1500次循环）。在对每个样本施加静态45°斜向压缩负荷后确定直至失效的负荷及失效模式。采用单因素和双因素方差分析（ANOVA）、Tukey事后检验和卡方检验来确定实验组和对照组之间具有统计学意义的相互作用。
所有样本均通过机械和热疲劳试验。观察到修复设计和材料类型之间存在统计学上的显著相互作用（p < 0.001）。与相同修复设计的其他材料相比，CZir组和CCera组在疲劳后直至失效的负荷显著更高（p≤0.001）。在两种设计中，氧化锆修复体的灾难性失效频率最高。与除CZir组（p = 0.345）外的所有组相比，完整牙齿的直至失效负荷显著更高（p≤0.042）。
单件式CAD/CAM树脂复合材料嵌体冠可为根管治疗后的前磨牙修复提供可靠选择。
如果采用适当的预备、材料选择和粘结方案，嵌体冠可以与桩冠一样有效。由于抗折性低和灾难性失效风险高，临床医生在开处方用氧化锆嵌体冠修复前磨牙时需要谨慎。
