利用低温等离子体促进牙本质反应性粘接剂作用效果的研究

Bonding technique based on resin materials has become one of the most crucial technology in dentistry. Nevertheless, bonding restorations which show a satisfactory effect in the short term have a durability, especially the resin-dentin bonding. The main source of dentin bonding strength comes from micro mechanical interlock between resin and demineralized collagen in the hybrid layer. The strength and stability of this physical bonding is limited. Besides, the use of the traditional etching technique results in the loss of both extrafibrillar and intrafibrillar minerals from dentin collagen. The poor infiltration of resin monomer into collagen matrix would induce to the degradation of exposed collagen. Two methods were used for solving the problems described above in our previous studies. The one is extrafibrillar demineralization process, which could preserve intrafibrillar minerals for reinforce of collagen fibrils. Another one is dentin-reactive adhesive. It contains isocyanate functional monomer which could react with polar groups in dentin for generation of chemical bonding between resin and dentin. In the present study, a safe, effective, clean and economic technique, nonthermal plasma treatment will be used to promote the chemical bonding created by novel dentin-reactive adhesive for cleaning, etching, activation and functionalization of dentin surface. These strategies would contribute to a better bonding durability.

树脂粘接修复已成为口腔临床不可或缺的关键技术。然而其修复效果在短期内良好，但耐久性却不甚理想，其弱点主要在于牙本质的粘接。目前牙本质粘接力的主要来源为混合层内树脂和胶原缠绕形成的微机械嵌合力，这种物理粘接的强度和稳定性都很有限。加之传统脱矿使牙本质胶原纤维内外矿物质完全丧失，而树脂无又法完全渗透包裹胶原，裸露的胶原极易降解并造成粘接的退变。因此本项目针对上述导致粘接退变的原因，拟利用低温等离子体这种安全高效、环保低成本的技术，联合申请人所在课题组前期和同期研究的基于纤维外脱矿和牙本质反应性粘接剂的新型粘接体系，从选择性去除胶原纤维外矿物质加强胶原强度，通过等离子体清洁、蚀刻、活化及修饰牙本质表面增加化学结合位点，以及利用牙本质反应性粘接剂中异氰酸酯功能基团与牙本质间形成强力稳定化学粘接的角度，起到显著改善牙本质粘接效果的作用，为延长树脂修复体临床寿命发挥重要作用。

本项目初步完成了新型低温等离子体发生装置样机的设计与研制。该发生装置通过介质阻挡放电，产生具有较大面积的低温刷形等离子体羽流，可产生氩气、氦气、氮气3种低温等离子体。通过对等离子体各种参数进行调整，目前已实现了低温和高效能的处理效果，达到临床使用的基本要求。氩气等离子体能够一定程度上增强牙本质表面的极性基团的活性，同时还能够清洁牙齿表面。粘接剂在经氩气等离子体预处理的牙本质表面渗透性更好，能够形成更多更长的树脂突结构，且与牙体组织的结合也更加紧密。氦气等离子体处理的牙本质粘接强度也得到了明显增强。此外，等离子体还有促进粘接剂聚合的效果。在项目扫描电镜实验研究过程中，发现当牙本质粘接界面在接收不同能量强度的扫描电镜电子束轰击时，会发生一定程度的损毁，并且损毁范围和程度与电子束能量相关，并由此衍生出一种可能用于牙本质粘接界面缺陷研究的新方法，即最先发生损毁的部位为界面的薄弱和缺陷处，从而实现在扫描电镜观察过程中直接对粘接界面的质量进行快速的评估。