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Abstract：
BACKGROUND: An optimum restoration for reconstructing endodontically treated teeth should provide excellent marginal adaptation, high fracture resistance as well as maximum tooth structure conservation. The purpose of this study was to evaluate the marginal adaptation and fatigue resistance of different coronal restorations in endodontically treated premolars.
METHODS: Thirty sound maxillary first premolars were endodontically treated and received MOD cavities. Teeth were randomly allocated into three groups (n = 10) according to the type of coronal restoration: Group R: polyethylene fibers (ribbond), fibers-reinforced composite (everX posterior) and final layer of nano-hybrid composite. Group O: indirect lithium disilicate overlay and Group C: fiber-post, resin composite restoration, and lithium disilicate crown. Marginal gap assessment was performed before and after thermocycling (5000 cycles) using stereomicroscope. Samples were subjected to stepwise-stress loading starting at 200 N, and increased by 100 N in each step until failure occurred. Statistical analysis was done by One-way ANOVA followed Tukey`s Post Hoc test for multiple comparison. Paired t test was used to compare the marginal adaptation before and after thermocycling. Survival probability was evaluated by Life table survival analysis. Failure mode analysis was performed with Chi-square test.
RESULTS: Marginal gap was significantly the lowest in group R (37.49 ± 5.05) and (42.68 ± 2.38), while being the highest in group C (59.78 ± 5.67) and (71.52 ± 5.18) in before and after thermocycling respectively (P < 0.0001). Fatigue resistance was the highest for group O (1310.8 ± 196.7), and the lowest for group R (905.4 ± 170.51) with a significant difference between groups (P < 0.0001). Crown group had the highest percentage (80%) of catastrophic failure, while, overlay group exhibited the lowest (20%).
CONCLUSIONS: Direct restoration without cuspal coverage using ribbon fibers with short FRC provided better marginal adaptation than indirect overlays and crowns, but fatigue resistance wasn\'t significantly improved. Adhesive ceramic overlays showed the best fatigue performance and the least catastrophic failure rate compared to both direct fiber-reinforced composite and indirect ceramic full coverage restorations.
CONCLUSIONS: Indirect adhesive overlays are a suitable, more conservative restorative option for endodontically treated teeth than full coverage restorations, especially when tooth structure is severely compromised.
METHODS: Thirty sound maxillary first premolars were endodontically treated and received MOD cavities. Teeth were randomly allocated into three groups (n = 10) according to the type of coronal restoration: Group R: polyethylene fibers (ribbond), fibers-reinforced composite (everX posterior) and final layer of nano-hybrid composite. Group O: indirect lithium disilicate overlay and Group C: fiber-post, resin composite restoration, and lithium disilicate crown. Marginal gap assessment was performed before and after thermocycling (5000 cycles) using stereomicroscope. Samples were subjected to stepwise-stress loading starting at 200 N, and increased by 100 N in each step until failure occurred. Statistical analysis was done by One-way ANOVA followed Tukey`s Post Hoc test for multiple comparison. Paired t test was used to compare the marginal adaptation before and after thermocycling. Survival probability was evaluated by Life table survival analysis. Failure mode analysis was performed with Chi-square test.
RESULTS: Marginal gap was significantly the lowest in group R (37.49 ± 5.05) and (42.68 ± 2.38), while being the highest in group C (59.78 ± 5.67) and (71.52 ± 5.18) in before and after thermocycling respectively (P < 0.0001). Fatigue resistance was the highest for group O (1310.8 ± 196.7), and the lowest for group R (905.4 ± 170.51) with a significant difference between groups (P < 0.0001). Crown group had the highest percentage (80%) of catastrophic failure, while, overlay group exhibited the lowest (20%).
CONCLUSIONS: Direct restoration without cuspal coverage using ribbon fibers with short FRC provided better marginal adaptation than indirect overlays and crowns, but fatigue resistance wasn\'t significantly improved. Adhesive ceramic overlays showed the best fatigue performance and the least catastrophic failure rate compared to both direct fiber-reinforced composite and indirect ceramic full coverage restorations.
CONCLUSIONS: Indirect adhesive overlays are a suitable, more conservative restorative option for endodontically treated teeth than full coverage restorations, especially when tooth structure is severely compromised.
摘要：
背景：重建经牙髓治疗的牙齿的最佳修复应提供出色的边缘适应性，高抗断裂性以及最大的牙齿结构保护。这项研究的目的是评估经牙髓治疗的前磨牙的不同冠状修复体的边缘适应性和抗疲劳性。
方法：对30颗上颌第一前磨牙进行牙髓治疗并接受MOD腔。根据冠状修复的类型，将牙齿随机分为三组（n=10）：R组：聚乙烯纤维（ribond），纤维增强复合材料（everX后）和最终层的纳米混合复合材料。O组：间接二硅酸锂覆盖层，C组：纤维柱，复合树脂修复，和二硅酸锂冠。使用立体显微镜在热循环（5000个循环）之前和之后进行边缘间隙评估。样品从200N开始接受逐步应力加载，并在每个步骤中增加100N，直到发生故障。通过单向ANOVA进行统计分析，然后进行Tukey的PostHoc检验进行多重比较。采用配对t检验比较热循环前后的边际适应。通过生命表生存分析评估生存概率。采用卡方检验进行失效模式分析。
结果：R组边缘间隙最低（37.49±5.05）和（42.68±2.38），在热循环前后，C组最高（59.78±5.67）和（71.52±5.18）（P<0.0001）。O组的抗疲劳性最高（1310.8±196.7），R组最低（905.4±170.51），组间差异有统计学意义（P<0.0001）。皇冠组的灾难性失败比例最高（80％），while,覆盖组表现最低(20%)。
结论：使用具有短FRC的带状纤维在没有牙尖覆盖的情况下直接恢复比间接覆盖和牙冠提供了更好的边缘适应，但抗疲劳性没有显著提高。与直接纤维增强复合材料和间接陶瓷全覆盖修复体相比，粘合陶瓷覆盖层显示出最佳的疲劳性能和最小的灾难性故障率。
结论：间接粘合覆盖层是合适的，牙髓治疗的牙齿比全覆盖修复更保守的修复选择，特别是当牙齿结构严重受损时。
方法：对30颗上颌第一前磨牙进行牙髓治疗并接受MOD腔。根据冠状修复的类型，将牙齿随机分为三组（n=10）：R组：聚乙烯纤维（ribond），纤维增强复合材料（everX后）和最终层的纳米混合复合材料。O组：间接二硅酸锂覆盖层，C组：纤维柱，复合树脂修复，和二硅酸锂冠。使用立体显微镜在热循环（5000个循环）之前和之后进行边缘间隙评估。样品从200N开始接受逐步应力加载，并在每个步骤中增加100N，直到发生故障。通过单向ANOVA进行统计分析，然后进行Tukey的PostHoc检验进行多重比较。采用配对t检验比较热循环前后的边际适应。通过生命表生存分析评估生存概率。采用卡方检验进行失效模式分析。
结果：R组边缘间隙最低（37.49±5.05）和（42.68±2.38），在热循环前后，C组最高（59.78±5.67）和（71.52±5.18）（P<0.0001）。O组的抗疲劳性最高（1310.8±196.7），R组最低（905.4±170.51），组间差异有统计学意义（P<0.0001）。皇冠组的灾难性失败比例最高（80％），while,覆盖组表现最低(20%)。
结论：使用具有短FRC的带状纤维在没有牙尖覆盖的情况下直接恢复比间接覆盖和牙冠提供了更好的边缘适应，但抗疲劳性没有显著提高。与直接纤维增强复合材料和间接陶瓷全覆盖修复体相比，粘合陶瓷覆盖层显示出最佳的疲劳性能和最小的灾难性故障率。
结论：间接粘合覆盖层是合适的，牙髓治疗的牙齿比全覆盖修复更保守的修复选择，特别是当牙齿结构严重受损时。
