Abstract：
The objective of the study was to evaluate the effect of different restorative protocols on fracture resistance of root canal-treated molars. 48 mandibular first molars were used and divided into six groups (n = 8); G1 (negative control): teeth kept intact. G2 (positive control): teeth had root canal treatment and standard MOD cavity preparations but kept unrestored. G3: prepared as G2 and directly restored with VitaEnamic ceramic overlays (CO). G4: as G3, but the pulp chamber was restored first with smart dental restorative (SureFil SDR flow = SDR) bulk-fill flowable composite base. G5: as G3, but the pulp chamber was restored first with SonicFill (SF) bulk-fill composite base. G6: as G3, but the pulp chamber was restored first with a fiber-reinforced composite (FRC) base. All samples were subjected to thermocycling between 5 °C and 55 °C in a water bath for a total of 2000 cycles with 10 s dwell time. Then specimens were individually mounted on a computer-controlled testing machine with a load cell of 5 kN, and the maximum load to produce fracture (N) was recorded. Data were analyzed using one-way ANOVA followed by Tukey\'s post hoc test (P = 0.05). There was a significant difference between the groups (P < 0.001). Teeth restored with FRC and ceramic overlays had the highest load-bearing capacity. Pulp chamber restoration with either FRC or SDR before ceramic overlay fabrication provided significantly better tooth reinforcement than ceramic overlay alone (P < 0.001). Fracture modes were analyzed to determine the type of fracture as repairable or catastrophic, where FRC + CO and SDR + CO groups had favorable fracture modes that were mostly repairable. When restoring root canal-treated molars with overlays, the pulp chamber should be sealed with either FRC or SDR to ensure the best possible fracture resistance. The clinical relevance of the study is that a new simple restorative protocol is presented to enhance the survival of root canal-treated molars using ceramic overlays.
摘要：
该研究的目的是评估不同修复方案对根管治疗磨牙的抗骨折性的影响。使用48颗下颌第一磨牙，分为六组（n=8）；G1（阴性对照）：牙齿保持完整。G2（阳性对照）：牙齿进行了根管治疗和标准的MOD腔准备，但未恢复。G3:制备为G2并直接用VitaEnamic陶瓷覆盖层(CO)修复。G4：为G3，但首先使用智能牙科修复剂（SureFilSDR流量=SDR）散装填充可流动复合底座恢复牙髓室。G5：为G3，但首先用SonicFill（SF）散装填充复合底座恢复纸浆室。G6：为G3，但首先用纤维增强复合材料（FRC）底座恢复了纸浆室。所有样品在水浴中在5°C至55°C之间进行热循环,共2000个循环,停留时间为10秒。然后将样品分别安装在具有5kN的测力传感器的计算机控制的测试机上，记录产生断裂的最大载荷(N)。数据采用单因素方差分析和Tukey的事后检验(P=0.05)。组间差异有统计学意义(P<0.001)。用FRC和陶瓷覆盖层修复的牙齿具有最高的承载能力。在陶瓷覆盖层制造之前，使用FRC或SDR进行的纸浆室修复比单独的陶瓷覆盖层提供了更好的牙齿增强效果（P<0.001）。分析了骨折模式，以确定可修复或灾难性的骨折类型，其中FRC+CO和SDR+CO组有良好的骨折模式，大多可修复。用覆盖层修复根管治疗的磨牙时，纸浆室应该用FRC或SDR密封，以确保最佳的抗断裂性。该研究的临床相关性是提出了一种新的简单修复方案，以提高使用陶瓷覆盖层的根管治疗磨牙的存活率。
