Huang Gang, Liu Si-Yi, Qiu Dong, Dong Yan-Mei
Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, PR China.
Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences & University of Chinese Academy of Sciences, Beijing, PR China.
J Dent Sci. 2023 Jan;18(1):27-33. doi: 10.1016/j.jds.2022.08.004. Epub 2022 Aug 20.
BACKGROUND/PURPOSE: The root fracture resistance of endodontically treated teeth is decreased significantly, and it is more likely to fracture. This study aimed to evaluate the effect of a novel root canal sealer based on bioactive glass (BG) on root fracture resistance and explore its mechanism.
The BG-based root canal sealer (BG Sealer) was prepared by mixing a kind of bioactive glass (10.8% PO, 54.2% SiO, 35% CaO, mol.%, named PSC), zirconia (ZrO) powder, sodium alginate (SA) and phosphate solution (PS). A pH meter was used to measure the pH of simulated body fluid (SBF) after immersion with BG Sealer at different time. After preparing the samples of BG sealer with a diameter of 4 mm and a height of 6 mm, the compressive strength was tested by a universal testing machine. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to detect and analyze the mineral status of root canal systems filled with BG Sealer. The push out test was used to measure the push out bond strength of BG Sealer. The fracture resistance of root canals filled with BG Sealer was detected by the compressive loading test. Bioceramic root canal sealer iRoot SP was set as the control group.
(1) Physicochemical properties: The pH value of SBF immersed with BG Sealer increased slightly up to 7.68, while the pH of SBF immersed with iRoot SP increased to 12.08. The compressive strength of the novel BG Sealer was 4.62 ± 1.70 MPa, which was lower than that of iRoot SP ( < 0.05). (2) Mineralization: The hydroxyapatite layers were observed on the surface of BG Sealer and iRoot SP after being immersed in SBF for 4 weeks. BG Sealer and iRoot SP were both able to penetrate into the dentin tubules, duplicate the morphology of root canals well, and form a layer of hydroxyapatite. (3) Adhesion to dentin: There was no significant difference between the push out bond strength of the novel BG Sealer and iRoot SP ( > 0.05). (4) Fracture resistance: After immersion in SBF for 4 weeks, the fracture resistance of roots filled with BG Sealer and iRoot SP was 454.16 ± 155.39 N and 445.50 ± 164.73 N, respectively, both of which were not statistically different from that of the roots unprepared and unfilled (394.07 ± 62.12 N) ( > 0.05), whereas higher than that of the roots prepared and unfilled (235.36 ± 83.80 N) ( < 0.05).
The novel BG Sealer has good adhesion to the root dentin, can penetrate into the dentin tubules to generate minerals, and meanwhile can improve the fracture resistance of the roots after root canal treatment. It is expected to be a bioactive root canal sealer with good clinical application prospects.
背景/目的：经根管治疗的牙齿的抗折性显著降低，且更容易发生折断。本研究旨在评估一种基于生物活性玻璃（BG）的新型根管封闭剂对牙根抗折性的影响，并探讨其作用机制。
通过将一种生物活性玻璃（10.8% P₂O₅、54.2% SiO₂、35% CaO，摩尔百分比，命名为PSC）、氧化锆（ZrO₂）粉末、海藻酸钠（SA）和磷酸盐溶液（PS）混合来制备基于BG的根管封闭剂（BG封闭剂）。使用pH计测量在不同时间用BG封闭剂浸泡后的模拟体液（SBF）的pH值。制备直径为4mm、高度为6mm的BG封闭剂样品后，用万能试验机测试其抗压强度。使用扫描电子显微镜（SEM）和能量色散X射线光谱仪（EDS）检测和分析用BG封闭剂充填的根管系统的矿化状态。采用推出试验测量BG封闭剂的推出粘结强度。通过压缩加载试验检测用BG封闭剂充填的根管的抗折性。将生物陶瓷根管封闭剂iRoot SP设为对照组。
（1）理化性质：用BG封闭剂浸泡的SBF的pH值略有升高，达到7.68，而用iRoot SP浸泡的SBF的pH值升至12.08。新型BG封闭剂的抗压强度为4.62±1.70MPa，低于iRoot SP（P<0.05）。（2）矿化：在SBF中浸泡4周后，在BG封闭剂和iRoot SP的表面观察到羟基磷灰石层。BG封闭剂和iRoot SP均能够渗入牙本质小管，很好地复制根管形态，并形成一层羟基磷灰石。（3）与牙本质的粘结：新型BG封闭剂与iRoot SP的推出粘结强度之间无显著差异（P>0.05）。（4）抗折性：在SBF中浸泡4周后，用BG封闭剂和iRoot SP充填的牙根的抗折性分别为454.16±155.39N和445.50±164.73N，两者与未预备和未充填的牙根（394.07±62.12N）相比均无统计学差异（P>0.05），但高于预备但未充填的牙根（235.36±83.80N）（P<0.05）。
新型BG封闭剂对牙根牙本质具有良好的粘结性，能够渗入牙本质小管以生成矿物质，同时可以提高根管治疗后牙根的抗折性。有望成为一种具有良好临床应用前景的生物活性根管封闭剂。
