季铵盐改性生物陶瓷根管封闭剂的封闭及抗菌性能研究^*

Study of the Sealing and Antibacterial Properties of Bioceramic Root Canal Sealers Modified With Quaternary Ammonium Salt

摘要

目的 利用季铵盐甲基丙烯酸十二烷基二甲铵（dimethylaminododecyl methacrylate, DMADDM）对不具备抗菌性能的生物陶瓷类根管封闭剂iRoot SP进行改性，制备新型封闭剂。方法 通过细胞计数试剂盒-8（cell counting kit-8, CCK-8）评估改性根管封闭剂的细胞毒性，根据国际标准化组织（International Organization for Standardization, ISO）的方法测试封闭剂的溶解度和流动性。分别利用显微计算机断层扫描（micro-CT）及共聚焦激光扫描显微镜（confocal laser scanning microscope, CLSM）评估封闭性及渗透性。通过菌落形成单位（colony-forming unit, CFU）计数、结晶紫染色、扫描电镜（scanning electron microscope, SEM）及活死染色评估封闭剂对粪肠球菌生物膜的抗菌性。结果 DMADDM质量分数为0.625%时，改性封闭剂显示出良好的生物相容性（P>0.012 5）。经质量分数0.625%的DMADDM改性封闭剂的流动性（>17 mm）及溶解度（<3%）均符合ISO标准，且与iRoot SP相比差异无统计学意义（P>0.05）。DMADDM改性对封闭剂在牙根不同位置的封闭性及渗透性均无影响（P>0.05）。抗菌实验显示，未老化时改性封闭剂降低了粪肠球菌生物膜的CFU计数（0.518±0.333 vs. 8.156±0.011，P<0.001）及生物膜量（均值差为86.94%，95%可信区间：74.82%～99.07%，P<0.000 1），但老化1周（7.327±0.068 vs. 7.422±0.035）或老化4周（7.479±0.065 vs. 7.581±0.071）后改性封闭剂的CFU计数与iRoot SP组无明显差异（P>0.05）。同时，活死染色及SEM显示改性封闭剂可以抑制粪肠球菌的生物膜形成。结论 质量分数为0.625%的DMADDM改性后的iRoot SP表现出良好的生物相容性、封闭性和渗透性，显著改善了封闭剂抗粪肠球菌生物膜的能力，为生物陶瓷类根管封闭剂的抗菌改性提供了思路。

Abstract

Objective To modify the non-antibacterial bioceramic root canal sealant iRoot SP with the quaternary ammonium salt dimethylaminododecyl methacrylate (DMADDM) and to develop a new type of sealant. Methods The cytotoxicity of the modified root canal sealant was evaluated using the cell counting kit-8 (CCK-8). The solubility and flowability of the sealant were tested according to International Organization for Standardization (ISO) methods. The sealing ability and penetrability of the sealant were assessed by micro-computed tomography (micro-CT) and confocal laser scanning microscope (CLSM). The antibacterial activity of the sealant against Enterococcus faecalis biofilm was evaluated by colony-forming unit (CFU) counting, crystal violet staining, scanning electron microscope (SEM), and live/dead staining. Results When the DMADDM mass fraction was 0.625%, the modified sealant demonstrated good biocompatibility (P > 0.012 5). The flowability (> 17 mm) and solubility (< 3%) of the sealant modified with 0.625% DMADDM met ISO standards and showed no significant difference compared with iRoot SP. DMADDM modification did not affect the sealing ability or penetrability of the sealant at different positions of the tooth root ( P > 0.05). Antibacterial experiments showed that the modified sealant reduced the CFU count (0.518 ± 0.333 vs. 8.156 ± 0.011, P < 0.001) and the amount of biofilm (mean difference of 86.94%, 95% confidence interval: 74.82%-99.07%, P < 0.000 1) of Enterococcus faecalis biofilm at the unaged stage. However, after 1 week of aging (7.327 ± 0.068 vs. 7.422 ± 0.035) or 4 weeks of aging (7.479 ± 0.065 vs. 7.581 ± 0.071), the CFU count of the modified sealant showed no significant difference from the iRoot SP group ( P > 0.05). Live/dead staining and SEM also showed that the modified sealant could inhibit the formation of Enterococcus faecalis biofilm. Conclusion iRoot SP modified with 0.625% DMADDM exhibited good biocompatibility, sealing ability, and penetrability, and significantly improved resistance to Enterococcus faecalis biofilm, providing a new approach for the antibacterial modification of bioceramic root canal sealants.

关键词

根管封闭剂 / iRoot SP / DMADDM / 粪肠球菌

Key words

Root canal sealers / iRoot SP / DMADDM / Enterococcus faecalis

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基金资助

*国家自然科学基金(82301058)

国家自然科学基金(32571322)

国家自然科学基金(82071106)

四川大学华西口腔医（学）院人才队伍建设科研经费资助项目(RCDWJS2024-(2))