琼脂糖水凝胶矿化模型诱导牙本质仿生矿化的研究

发布时间：2018-05-10 05:55

本文选题：牙本质 + 羟基磷灰石　；参考：《安徽医科大学》2017年硕士论文

【摘要】：背景牙体硬组织(牙釉质、牙本质、牙骨质)一旦受损,机体很难实现自愈性修复,临床上必须采用人工材料进行修复。当前,体外研究已经证实,载有钙磷离子的新型琼脂水凝胶仿生矿化模型能够诱导牙体硬组织再生修复,和传统的充填治疗相比,这种牙体硬组织自愈性仿生修复更符合生理机制,生成的矿化物的组分、晶体结构、硬度与人牙体组织高度相似。因而,该仿生矿化模型很可能在龋病、磨损和牙本质敏感等疾病的治疗上具有良好的应用前景。目的载有钙磷离子的新型琼脂水凝胶仿生矿化模型能够诱导牙本质的再生修复。但是,前期体外实验是在一个稳定的、清洁的、不受口腔环境影响的薄层牙本质片上进行的。和单一恒定的实验室环境相比,人类的口腔微环境显然更为复杂和多变,为了探索该仿生矿化模型在人类复杂的口腔微环境下的实际矿化效果并实现其临床应用转化,本实验构建了以新西兰大白兔为对象的实验动物模型,利用兔口腔微环境,探索该水凝胶仿生矿化模型在真实口腔环境下诱导牙本质仿生矿化的能力,为该仿生矿化模型在复杂的人类口腔微环境下的实际临床应用转化做准备。方法选取新西兰大白兔(兔龄3个月,平均体重2.25 kg)为研究对象,全麻后磨除上、下前牙唇面釉质层,暴露牙本质于口腔环境。选择上前牙为实验组,下前牙为自身对照组。首先,制作兔上颌前牙的个性化透明塑料托盘(用于盛载和保护水凝胶仿生矿化体系);然后,在酸蚀去除玷污层的牙本质表面覆盖一层2mm厚的Ca Cl_2水凝胶,待水凝胶胶凝后,将载有一层2mm厚Na_2HPO_4水凝胶的个性化透明塑料托盘戴入兔上颌牙,确保Ca Cl_2水凝胶与Na_2HPO_4水凝胶充分接触。琼脂水凝胶矿化时间持续8小时(定义为一个矿化周期)。对照组的下前牙酸蚀后不处理直接暴露于口腔。分别矿化1,3个周期后,拔除实验组和对照组前牙,利用场发射扫描电镜(SEM),X射线衍射仪(XRD)和纳米压痕仪对牙本质表面的沉积层进行表征和分析。结果扫描电镜结果显示在酸蚀的牙本质表面形成了厚厚的一层晶体层。X射线衍射仪结果证实新形成晶体层为高度矿化的羟基磷灰石晶体层,在脱矿的胶原纤维表面及内部有大量的羟基磷灰石晶体沉积,形成了矿化的牙本质。在矿化的牙本质表面羟基磷灰石晶体的c轴方向与牙本质的表面垂直并紧密结合沉积于其表面,牙本质小管被羟基磷灰石晶体封闭,新沉积的羟基磷灰石晶体层其弹性模量和纳米硬度与天然牙本质相近,从而实现了牙本质的再矿化。结论在兔的口腔环境中,琼脂水凝胶仿生矿化模型具有形成牙体微结构的能力,从而实现脱矿牙本质的再生修复,并为牙本质暴露相关疾病,如酸蚀症、磨损、牙本质敏感症等的治疗提供了一种新的治疗方法。
[Abstract]:Background once the hard tissue (enamel, dentin, cementum) is damaged, it is very difficult for the body to achieve self-healing repair. At present, in vitro studies have shown that a new Agar hydrogel biomimetic mineralization model containing calcium and phosphorus ions can induce hard tissue regeneration and repair, compared with traditional filling therapy. The biomimetic restoration of hard tissue is more in line with the physiological mechanism. The composition, crystal structure and hardness of the mineralized substance are highly similar to those of the human tooth tissue. Therefore, the biomimetic mineralization model is likely to have a good prospect in the treatment of dental caries, wear and dentin sensitivity. Aim A new bionic mineralization model of Agar hydrogel containing calcium and phosphorus ions can induce dentin regeneration and repair. However, pre-vitro experiments were performed on a stable, clean, oral-free, thin-layer dentin. Compared with the single and constant laboratory environment, the oral microenvironment of human is obviously more complex and changeable. In order to explore the actual mineralization effect of the biomimetic mineralization model in the complex oral microenvironment of human beings and to realize its clinical application transformation, An experimental animal model of New Zealand white rabbit was established in this study. The ability of the hydrogel biomimetic mineralization model to induce biomimetic mineralization of dentin in real oral environment was explored by using rabbit oral microenvironment. This biomimetic mineralization model can be applied in complex human oral microenvironment. Methods New Zealand white rabbits (3 months old, average weight 2.25 kg) were selected as the study objects. After general anesthesia, the enamel layer on the labial surface of the lower anterior teeth was removed, and the dentin was exposed to the oral environment. The upper anterior teeth were selected as the experimental group and the lower anterior teeth as the self-control group. First, a personalized transparent plastic tray for rabbit maxillary anterior teeth (used to hold and protect hydrogels from biomimetic mineralization system) was made. Then, a layer of 2mm thick Ca Cl_2 hydrogel was coated on the surface of dentin with acid etching and tarnishing layer, after which the hydrogel was cemented. A personalized transparent plastic tray with a layer of 2mm thick Na_2HPO_4 hydrogels was worn into rabbit maxillary teeth to ensure that Ca Cl_2 hydrogels were in full contact with Na_2HPO_4 hydrogels. Agar hydrogel mineralization lasts 8 hours (defined as a mineralization cycle). In the control group, the anterior teeth of the control group were exposed directly to the oral cavity without treatment after acid etching. After 1,3 cycles of mineralization, the anterior teeth of the experimental group and the control group were extracted, and the deposit layer on the dentin surface was characterized and analyzed by field emission scanning electron microscopy (SEM) and nano-indentation apparatus. Results the SEM results showed that a thick layer of crystal layer was formed on the etched dentin surface. The results of X-ray diffractometer confirmed that the newly formed crystal layer was highly mineralized hydroxyapatite crystal layer. A large amount of hydroxyapatite crystals were deposited on the surface and interior of demineralized collagen fibers, forming mineralized dentin. The c-axis of hydroxyapatite crystals on the surface of mineralized dentin is perpendicular to the surface of dentin and deposited on the surface of dentin, and the dentine tubules are sealed by hydroxyapatite crystals. The elastic modulus and nano-hardness of the newly deposited hydroxyapatite crystal layer are similar to those of natural dentin, so that the dentin can be remineralized. Conclusion in rabbit oral environment, Agar hydrogel biomimetic mineralization model has the ability to form dentin microstructures, thus to achieve the regeneration and repair of demineralized dentin, and is related to dentin exposure diseases, such as acidosis, wear and tear. The treatment of dentin hypersensitivity provides a new treatment method.
【学位授予单位】：安徽医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R781

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