【作者】 韩纪梅；

【导师】 李玉宝；

【作者基本信息】 四川大学 ， 生物医学工程， 2005， 博士

【摘要】 我国人均患龋率为40%。据朱希涛教授估算,以每个龋齿患者平均有两个龋齿,则我国有13亿龋齿有待充填修复,需要大量的齿科充填材料。出于健康、美观以及保护自身牙体组织的考虑,人们倾向选择新型齿科修复材料,使银汞合金正逐渐走出人们的视线。自从1962年美国学者Bowen R L发明了以Bis-GMA树脂为基质,以二氧化硅为填料的牙科复合树脂以来,复合树脂的发展一直十分迅速,目前在临床上的应用范围也越来越广。与银汞合金相比,复合树脂的固化收缩率大和耐磨性不足也限制了它的应用。人们渴望开发性能更为优越的材料来满足口腔临床应用的需要。 众所周知,人体骨和牙齿是由天然有机分子构成的连续相和弥散其中的羟基磷灰石纳米晶粒所组成的复合材料。因此,从仿生学角度出发,通过模仿人牙的组成成分、结构性质并制备出与人牙无机质在组成、晶体结构、形貌、特定的活性基团及微量元素含量等方面极其相似的纳米类骨磷灰石晶体,将其加入到高分子或树脂中可以发挥其生物功能效应,并有助于提高复合材料的力学性能。如n-HA与骨直接键合可促进骨和牙齿的再矿化,有利于骨重建和防龋能力的提高。为了制备类人体组织的生物医用材料,羟基磷灰石和高分子的复合材料被广泛地研究。通过模拟自然骨的组成结构与功能,利用不同性质的材料优化组合而形成的钙-磷/高聚物复合材料由于能够兼具钙-磷材料生物活性和高分子材料的力学性能近年引起了人们极大的兴趣和广泛的关注。这种修复材料的出现和发展,为获得结构和性质类似于人体组织的生物材料开辟了一条广更多还原

【Abstract】 There are more than 40 percent of the whole population in our country who suffer from their caries. If one patient has two caries, there would be more than 1.3 billion caries which need repairing. Therefore, it would urgently demand a huge amount of dental restorative materials said by professor ZHU Xi-tao. Amalgam is becoming less and less relevant as a standard restorative. Patients’increased health-awareness, their desire for enhanced esthetics, continued discussions on amalgam and recent developments in materials’ research are all reasons for developing new dental restoratives. Composite resin, invented by Bowen R L, an American scholar in 1962, in which Bis-GMA resin was taken as the matrix and silica etc. as the fillings, has already becoming a kind of useful materials instead of amalgam to repair hard tissue in clinical application. But the main problems incurred with composite fillings in the posterior region to date have been their tendency to form marginal gaps due to polymerization shrinkage and lack of strength and bioactivity. Apart from polymerization shrinkage, contact with the opposingdentition also causes elastic deformation of the filling material, which adversely affects its bond strength on the tooth structure. The above mentioned shortagesassociated with the current composite resin limit its further widespread application.As we know, various biological materials existing in nature, such as shells、 pearls、 bone and teeth, are all inorganic/organic composites with good mechanical properties. In order to fabricate biomedical materials which imitate human hard tissue to great extent, hydroxyapatite (HA)/polymer composites have attracted much attention because such composites may have osteoconductivity as a result of the presence of HA. HA has been extensively investigated due to its excellent biocompatibility, bioactivity and osteoconductivity as well as its similarity to the main mineral component of bone and teeth. According to the principle of biomimesis, if we could synthesize a kind of HA which has a similar composition, crystal structure, morphology, and crystalinity to that of human teeth, and then mix them with the current composite resin, some expected functions would be exhibited when it is applied to repair human teeth, such as the effect of biological function. Furthermore, the mixed HA would be conducive to the teeth reconstruction and the ability of anti-caries.In this research, the properties of CHARISMA(?) composite resin and the composition and structure of human posterior teeth were investigated firstly. Then the teeth-like nano-hydroxyapatite were fabricated. In addition, the interaction between n-HA and silane coupling agent was studied. On the basis, the n-HA/CHARISMA(?) composite was prepared by melting mixation technique.1. CHARISMA(?) resin is one kind of composites which consists of 71.44wt% inorganic filling materials and 28.56wt% organic phase. The inorganic materials are made of amorphous silica, barium and aluminum glass and titanium’oxide. The organic phase is a substance which contains: -OH, -C=O, -CH3 and -CH2. The testing results show that CHARISMA? resin matchs the basic requirement for composite resin according to GB11749-89, while its bioactivity and biocompatibility need to be further improved since there is no calcium and phosphate ions present in the resin.2. The crystal morphology and composition of human dental apatite were investigated using IR, XRD and TG techniques. The results show that two carbonate substitution types (A and B) exist in human posterior dental apatite, of which, carbonate apatites (A-type, substitution for -OH) have increased lattice constants a, and B-type, substitution for PO43-, are usually characterized by reduced a lattice constant. With the increase of calcining tempreture, the carbonates located in both A and B type substitution sites escaped from the dental apatite lattice and A-type carbonate disappeard in relatively low sinter temperature, but appeared again with the further increase of tempreture; while the B-type carbonate existed all the time with tempreture increase although its quantity decreased. XRD spectra show that there is an extensive degree of peak broading for the human dental apatite dried at 80 ℃ and the peaks become relatively sharp and well-resolved at high temperature, indicating that the crystal size and crystallizability of the teeth apatite increases with the thermal treatment temperature. Thermo gravimetric analysis showed that there were different types of water loss at temperature between 25℃ and 1000℃.The dentine contains more water and organic material, so its weigt loss was greater than that of enamel. The apatite crystals in enamel linked much closer than those of dentine. Therefore there would need more energy to break enamel than dentin. Those analyse provide a promising perspective for the tooth-like restorative material preparation.Nano-apatite crystals were made from hydrothermal treatment at 145 ℃ under normal pressure. The crystal morphology and composition of the synthesized nano-HA were investigated using TEM, IR, XRD, ICP and XPS techniques and were also compared with those of human posterior teeth. The results indicate that nano-apatite crystals have a similar composition, crystal structure, morphology and crystalinity to those of human teeth, and also containing CO32- and Na+ ions. From the view of biomimesis, the CO32- and F ions or groups should be introduced to the nano-apatite to mimic the biological apatite as much as possible. The research provides a wy for further n-HA/dental resin composites preparation.3. n-HA surface wae treated with silane. The interface of n-HA and silanecoupling agent was investigated. An effective surface modification method was developed to treat n-HA crystals slurry by using γ-(trimethoxysilyl) propyl methacrylate as a coupling agent. FT-infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray photoelectron spectrum (XPS) were used to characterize the silane-modified n-HA. The experimental results showed that peaks of hydroxyl group of n-HA decrease greatly after n-HA treated by silane, implying the occurrence of possible chemical reaction between n-HA and silane. Moreover, several surface modification mechanism is involved, including hydrogen bond chemical bond as well as the charge effect. The analysis of n-HA/silane interface is important for further n-HA/polymer or n-HA/dental resin composites preparation.4. The n-HA/CHARISMA(?) resin was fabricated by melting mixation technique under the help of the diluent TEGDMA. The testing results showed that the proerties of the CHARISMA(?) resin could be changed by adding n-HA crystals, some characteristics were improved after the mixation of n-HA into CHARISMA(?) resin. The usage of diluent TEGDMA helps to enlarge the inorganic content of the composite but decreases the properties of composite. n-HA crystals should be added in the process of CHARISMA(?) resin formation.更多还原