奈米粒子填料與玻璃纖維應用於樹脂根管釘柱之製成

Abstract

奈米材料具有特殊機械、光電、化學及熱性質，如何運用在複合材料的改善，在今日是十分受囑目的研究課題。本實驗欲以奈米填料來取代或減少牙科纖維加強複合樹脂根柱中的纖維，並測試材料的性質，以評估其用於於臨床膺復治療的可行性。本研究選擇牙科常見之Bisphenol diglycidyl dimethacrylate (Bis-GMA)與Triethylene glycol dimethacrylate (TEGDMA) 為樹脂基質，在實驗的一開始，以機械強度測試，決定了使用的起始劑種類和用量比例。之後所加入的奈米填料為未修飾的多壁奈米碳管，以及以PMMA和GMA做表面化學修飾的奈米碳管。另一種加入的奈米填料為帶有8個甲基丙烯酸甲酯 (MMA)官能基的多面體矽氧烷寡聚物。最後將玻璃纖維加入含有奈米粒子的樹脂基質，比較這些複合材料的彈性模數，並以電子顯微鏡觀察各種材料之間的界面黏結關係。由三點彎曲測試的結果發現，加入奈米碳管以及多面體矽氧烷寡聚物的樹脂材料，彈性模數並沒有獲得改善，反而隨著奈米粒子的濃度增加而明顯下降。經電子顯微鏡觀察發現奈米碳管即使經過高分子的修飾，仍無法有效增加碳管與樹脂基質之間的作用力，奈米碳管聚集難以分散的問題仍無法突破。而由紅外線光譜儀和微硬度值的測量中發現，多面體矽氧烷寡聚物的含量愈多，複合樹脂材料的聚合程度愈低，可能因此降低了原本樹脂基質有的彈性模數。加入約60%的玻璃纖維，能使樹脂材料的彈性模數增加至20GPa以上，接近牙本質的彈性強度。而從電子顯微鏡的觀察發現，多面體矽氧烷寡聚物的含量增加至10 wt%，則纖維/樹脂複合材料的斷裂模式發生改變，可能是加入足量的奈米粒子能促進樹脂基質與玻璃纖維之間的黏結，將有利於應力的傳導。奈米材料於牙科複合樹脂材的應用上仍有其潛力，必須解決奈米粒子分散不良的問題。至於奈米材料對於纖維及樹脂複合材之間的作用機制，則需更進一步探討。

As size of matter is reduced until few nanometers, quantum effects significantly change material's optical, magnetic or electrical properties. The attraction of many researcher for this length scale depend on the different and often enhanced properties of matter compared with the same materials at a larger size. In this study, we mixed different kinds of nanoparticle in dental resin material. The purpose was to evaluate the possibility of decreasing the fraction or replacing the use of the fiber in fiber reinforced composite resin posts.First, the dual-cured initiator system for resin matrix (Bis-GMA + TEGDMA) was decided according to the result of microhardness test. Then, carbon nanotube (CNT) and polyhedral oligomeric Silsesquioxane (POSS) were added into resin matrix separately. Three kinds of carbon nanotube were used: unmodified multi-wall CNT, PMMA-grafted CNT and GMA-grafted CNT. POSS-MA (methacryl-POSS cage mixture) with 8 polymerizable methacrylate groups was chosen as the other nanoparticle filler in this study. In the third part, chopped glass fiber was used as reinforcement of composite.Elastic modulus of these nanoparticle/ fiber reinforced composite resin material was obtained by three point test. The fracture surface of specimens observed under SEM for evaluation of interaction among nanoparticle, glass fiber and resin matrix. Comparing the result of carbon nanotube/composite resin, the more CNT was added in resin system, the lower the elastic modulus. Results revealed the poor dispersion in all CNT specimens. This study discovered that the functionalized CNT cannot be dissolved nor dispersed through ultrasonic tip vibration. Also, POSS-MA is not beneficial in improvement of mechanical properties probably because of incomplete polymerization. The result of FTIR explained the assumption that as POSS-MA increases, the conversion rate of the polymer decreases. When the weight fraction of glass fiber was up to about 60%, the reinforced composite resin exhibited improved elastic modulus approaching to that of human dentin (about 20 GPa). SEM observation on the failure surface of specimens indicated that the enhanced mechanism is due to the interfacial bonding between the fibers and the surrounding matrix modified by nano-sized filler. As the result, 10wt% of POSS-MA was supposed to improve the stress conduction between the different materials in resin system. The similar tendency not found in the CNT composites might resulted from the tiny amount of CNT and its poor dispersion in resin. Nano-sized particle has the potential in development of dental composite material, but carbon nanotube should be well dispersed first. The interaction between nanoparticle and fiber, needed to be further investigated.