竹复合材料制备牙科纤维桩灭菌前后的力学性能变化及生物相容性研究

Changes in mechanical properties and biocompatibility of dental fiber post prepared by bamboo composite material before and after sterilization

背景竹纤维是一种产量丰富的天然植物纤维,其力学性能可与玻璃纤维相媲美,是一种临床应用前景广阔的生物材料。目的研发一种低模量高强度的竹纤维复合材料作为牙科纤维桩材料。方法采用树脂传递模塑法制备竹纤维复合材料,将竹纤维复合材料随机分为两组,分别用于力学性能实验和生物相容性实验。力学性能实验分为对照组和灭菌组,对照组未灭菌,灭菌组通过121℃和2.2 MPa的高压灭菌器灭菌30 min。高精度微力学试验机分析灭菌前后竹复合材料的力学性能变化和断裂形式的荷载-位移曲线变化。扫描电子显微镜观察灭菌前后竹复合材料的表面形貌和断裂形貌。生物相容性实验包括CCK-8细胞毒性实验、细胞周期和凋亡实验、溶血实验。CCK-8细胞毒性实验分为阴性对照组、空白对照组和浸提液组,阴性对照组为正常培养基培养的细胞,空白对照组为无细胞的正常培养基,浸提液组为制备不同浓度(25%、50%、75%、100%)的竹纤维复合材料浸提液;细胞周期实验分为阴性对照组和处理组,阴性对照组为正常培养基培养的细胞,处理组为100%浓度的浸提液;细胞凋亡实验分为对照组和处理组,对照组为正常培养基培养的细胞,处理组为100%浓度的浸提液;溶血试验为实验组、阴性对照组和阳性对照组,实验组为100%浓度的浸提液,阴性对照组为0.9%氯化钠注射液,阳性组为蒸馏水,进一步验证竹纤维复合材料的生物相容性。结果未灭菌的对照组与灭菌组相比,弯曲模量[(9±2)GPa vs(11±4)GPa]和弯曲强度[(498±95)MPa vs(496±30)MPa]差异均无统计学意义(P>0.05)。载荷-位移曲线显示,未灭菌的对照组相比灭菌组有较好的断裂模式,未灭菌的对照组呈梯度破坏,灭菌组呈脆性断裂。扫描电镜显示,未灭菌的对照组和灭菌组的纤维和树脂表面形貌结合较好;未灭菌的对照组的断裂形貌为纤维拔出,灭菌组的断裂形貌为树脂基体的整体断裂。CCK-8结果显示,在短期内竹纤维复合材料100%浓度的浸提液吸光度值与阴性对照组相比,差异有统计学意义(P<0.01),100%浸提液的增殖能力最强。细胞周期结果显示,100%浓度的浸提液在第5天有较好的细胞增殖周期,与阴性对照组相比,差异无统计学意义(P>0.05)。细胞凋亡结果显示,100%浓度的浸提液在第5天无诱导细胞凋亡的作用,与阴性对照组相比,差异无统计学意义(P>0.05)。溶血试验表明,实验组竹纤维复合材料浸提液的溶血率为2.69%,溶血率<5%,与阳性对照组相比,差异有统计学意义(P<0.01)。结论灭菌前后的竹纤维复合材料力学性能相对稳定,且该复合材料具有良好的生物相容性,具有制备牙科纤维桩材料的潜力。

Background Bamboo fiber is a widely produced natural plant fiber,with mechanical properties comparable to those of glass fiber,making it a promising biomaterial.Objective To develop a bamboo fiber composite material characterized by low modulus and high strength,suitable for use in dental fiber posts.Methods The bamboo fiber composite was prepared using resin transfer molding and randomly divided into two groups for mechanical and biocompatibility testing.The mechanical properties were evaluated in a control group,which remained unsterilized,and a sterilization group,which underwent sterilization in a high-pressure autoclave at 121℃and 2.2 MPa for 30 minutes.A high-precision micromechanical testing machine was employed to assess changes in mechanical properties and fracture behavior pre-and post-sterilization,focusing on the load-displacement curves.Scanning electron microscopy was used to examine the surface and fracture morphologies before and after sterilization.Biocompatibility testing included CCK-8 cytotoxicity tests,cell cycle and apoptosis assays,and hemolysis tests.The CCK-8 cytotoxicity test divided samples into negative control groups with normally cultured cells,blank control groups with culture medium only,and experimental groups with various concentrations(25%,50%,75%,100%)of bamboo fiber composite extracts.The cell cycle and apoptosis assays compared a 100%concentration extract group with a negative control group.The hemolysis test involved experimental groups with a 100%concentration extract,physiological saline as the negative control,and distilled water as the positive control,to further assess the biocompatibility of the bamboo fiber composite.Results The non-sterilized control group exhibited a flexural modulus of(9±2)GPa and a strength of(498±95)MPa;the sterilized group showed a flexural modulus of(11±4)GPa and a strength of(496±30)MPa,with no significant difference between the two groups(P>0.05).Load-displacement curves indicated a more favorable fracture pattern in the control group,exhibiting gradient failure,unlike the brittle fracture observed in the sterilized group.Scanning electron microscopy revealed good integration of fiber and resin in both groups;the control group showed fiber pull-out,while the sterilized group exhibited cohesive fractures of the resin matrix.The CCK-8 assay revealed statistically significant difference in absorbance at 100%concentration of bamboo fiber composite extract compared to the control group(P<0.01),with the highest proliferative capability observed in the extract.Long-term cell cycle and apoptosis experiments showed that the 100%concentration extract maintained a favorable cell proliferation cycle without inducing apoptosis,demonstrating no significant difference from the control group(P>0.05).Hemolysis tests demonstrated a hemolysis rate of 2.69%for the bamboo fiber composite extract,significantly lower than 5%and markedly different from the positive control(P<0.01).Conclusion The mechanical properties of the bamboo fiber composite material remain relatively stable before and after sterilization,exhibiting good biocompatibility and potential for application in dental fiber post manufacturing.