【作者】 李文；

【导师】 王林；

【作者基本信息】 吉林大学 ， 口腔种植学（专业学位）， 2022， 硕士

【摘要】 研究背景:继发龋是临床上修复失败最常见、最主要的原因,多是由于在修复体-牙本质粘接界面发生微渗漏,细菌进一步入侵造成。继发龋预防的首要目标是抑制在修复体与牙体组织界面聚集滞留的龋病相关细菌生物膜。近年来,大量研究致力于将季铵盐化合物、氧化锌、二氧化钛纳米粒子等抗菌物质添加进口腔粘接剂中以达到迅速有效的抑制龋病相关病原菌。银纳米颗粒（NAg）也被添加到口腔粘接剂中赋予其抗菌特性。然而,将纳米银加入到口腔粘接剂中存在诸多问题。因此,理想的银载体材料将是解决上述问题的关键。分子筛是一种具有高度规则微孔结构的水合硅铝酸盐晶体材料,由MO₄四面体（M=Si或Al）通过氧离子相互连接而成。其中,纳米级EMT分子筛具备均一的孔道结构、高的孔隙率、较大的微孔体积和高的比表面积,从而具备较强的与阳离子进行交换的能力,因而能够作为银离子（Ag⁺）的理想载体,大量掺入牙本质粘接剂中,从而发挥抗菌性能并达到长期抗菌的作用,为临床上继发龋的预防提供新思路。实验目的:制备一种纳米级EMT型分子筛,并将与银离子交换不同时间后的EMT分子筛掺入牙本质粘接剂中形成一种抗菌粘接剂,探究其对牙本质-修复体边缘细菌生物膜形成的抑制作用,进而达到预防继发龋的形成。实验方法:1.采用低温无模板方法制备纳米级EMT分子筛,并通过离子置换反应将银离子负载于EMT分子筛孔道内。2.通过透射电子显微镜（TEM）、X射线衍射仪（XRD）、紫外-可见光吸收光谱（UV-vis）、氮气吸附法、电感耦合等离子体原子发射光谱（ICP-AES）等对载银前、后EMT分子筛结构进行表征。3.将EMT分子筛和与银离子交换10、20、40分钟的EMT分子筛（简称为:Ag⁺-EMT-1、Ag⁺-EMT-2、Ag⁺-EMT-3）分别加入到牙本质粘接剂中,并制备粘接剂-树脂层状圆盘,进一步通过细胞毒性实验检测上述材料的生物安全性。4.探究了纯粘接剂与分别含EMT、Ag⁺-EMT-1、Ag⁺-EMT-2和Ag⁺-EMT-3的共五组粘接剂对龋病相关细菌生物膜的抑制作用。对以变形链球菌（Streptococcus mutans,S.mutans）,戈登式链球菌（Streptococcus gordonii,S.gordonii）和血链球菌（Streptococcus sanguinis,S.sanguinis）为龋病的代表细菌进行了研究。测定了细菌的早期黏附情况、细菌菌落计数、细菌活/死染色及细菌代谢活性。结果:1.成功制备了六方晶型EMT分子筛,其结构呈亚稳定状态,易于发生离子交换。2.纳米级EMT分子筛与银离子的交换呈现时间依赖性,与银离子交换40分钟的EMT分子筛中Ag⁺含量最高,可达6.40 wt%,而与银离子交换10分钟的EMT分子筛中Ag⁺含量最低,为1.60 wt%。3.五组粘接剂样品均展现了良好的生物安全性。4.含与银离子交换的EMT分子筛的粘接剂表现出良好的抗细菌生物膜作用。含与银离子交换时间最长（40分钟）的EMT分子筛的粘接剂,细菌早期黏附、细菌生物量、生物膜生长和代谢活性的降低幅度最大。细菌生物膜CFU计数减少约2个数量级。结论:本研究合成了纳米级载银EMT分子筛,并将其加入到牙本质粘接剂中从而抑制龋病相关细菌生物膜。含有与Ag⁺交换EMT分子筛的牙本质粘接剂具有显著的抗菌性能,且不会影响牙齿修复的颜色和美观性能,可作为“生物活性”的粘接剂材料,显示出其在抗生物膜和抗龋病临床应用方面的潜在价值。更多还原

【Abstract】 Background:Secondary caries is the most common and major cause of clinical restoration failure.It is mostly caused by microleakage at the restoration-dentin bonding interface and further bacterial invasion.The primary goal of secondary caries prevention is to inhibit the accumulation of caries-related bacteria at the interface between restoration and dental tissue.In recent years,a large number of studies have been committed to developing antibacterial dentin adhesives by incorporating of antibacterial substances such as quaternary ammonium salts,zinc oxide,titanium dioxide nanoparticles,which could achieve rapid and effective inhibition of caries-related pathogens.Silver nanoparticles（NAg）may also be added to impart antibacterial properties into dentin adhesive.However,there are several challenges for incorporating NAg into dentin adhesives.Therefore,a reasonable Ag delivery system should be developed to solve aforementioned problems.Zeolite is a kind of hydrated sodium aluminosilicate crystalline material with highly regular microporous structure,composed of MO₄ tetrahedra（M=Si or Al）linked to each other by oxygen ions.Among them,nanosized EMT zeolite with uniform pore structure,high porosity,large pore volume and high specific surface areas,has the strong ability of ion exchange,thus it can be as an ideal carrier of silver ions.It can be added into dentin adhesive,and thus play a great role in antibacterial performance and achieve a long-term antibacterial effect,which provides a new way for the clinical prevention of secondary caries.Objective:The nanosized EMT zeolite was synthesized.EMT zeolite with different silver ion exchange time was incorporated into dentin adhesive to develop an antibacterial adhesive,which investigates the inhibition of biofilm formation at the dentin-restoration margin and to prevent the formation of secondary caries.Methods:1.Nanosized EMT zeolite was prepared with template-free at low temperature.Silver ions were loaded into the channels of EMT zeolite through ion exchange reaction.2.The structures of EMT zeolite loaded with silver before and after were characterized by transmission electron microscopy（TEM）,X-ray diffraction（XRD）,UV-visible absorption spectroscopy（UV-vis）,nitrogen adsorption method,inductively coupled plasma-atomic emission spectrometer（ICP-AES）.3.The EMT zeolite and the EMT zeolite exchanged with silver ion for 10,20,and 40min（referred to as:Ag⁺-EMT-1,Ag⁺-EMT-2,Ag⁺-EMT-3）were incorporated into the dentin adhesive respectively,and the adhesive-resin layered disks were prepared.And the biosafety of all samples was further evaluated by cytotoxicity test.4.The inhibitive effect of pure adhesives and adhesives containing EMT,Ag⁺-EMT-1,Ag⁺-EMT-2 and Ag⁺-EMT-3 on bacterial biofilms related to caries were investigated.Streptococcus mutans（S.mutans）,Streptococcus gordonii（S.gordonii）,and Streptococcus sanguinis（S.sanguinis）were selected as representative strains of cariogenic pathogens and to form single-species biofilms.Bacterial early attachment,colony-forming units（CFU）,live/dead staining,and metabolic activity were measured.Results:1.The hexagonal EMT zeolites have been successfully prepared.The structure of nanosized EMT zeolite is metastable and easy to occur ion exchange.2.The ion-exchange reaction between Ag⁺and nanosized EMT zeolite was time-dependent.The content of Ag⁺in the EMT zeolites with 40-min silver ion exchange was the highest,up to 6.40 wt%.While the content of Ag⁺in the EMT zeolites with 10-min silver ion exchange was the lowest,up to 1.60 wt%.3.The five groups of adhesive samples all presented good biosafety.4.The adhesive containing EMT zeolites exchanged with silver ions showed good anti-bacterial capability.The adhesive containing the EMT zeolite with the longest silver ion exchange time（40 min）showed the greatest reduction in early bacterial attachment,bacterial biomass,biofilm growth and metabolic activity.The CFU counts of bacterial biofilms decreased by about 2 orders of magnitude.Conclusions:This study synthesized the nanosized silver loading EMT zeolite which was further incorporated into the dentin adhesive to combat cariogenic biofilms.The dentin adhesives containing Ag⁺exchanged zeolites had remarkable antibacterial properties without affecting the color and aesthetic properties of dental restorations.It can be served as“bioactive”adhesive materials and revealed its potential value for anti-biofilms and anti-caries clinical applications.更多还原