Application of Thermoplastic Polyurethane and Urethane-acrylate in Dental Root Canal Material

中文摘要 本研究主要利用聚胺酯以及胺酯壓克力樹脂以研發牙科根管填充材料。實驗將分為根管填充針以及封填劑兩部份。根管填充針部分主要是利用聚胺酯做為基材，並使用氧化鋅做為填充料，開發應用於牙科根管填充針之氧化鋅及聚胺酯複合材料。結果顯示不論機械性質或熱性質方面，聚酯型聚胺酯做為基材之氧化鋅聚胺酯複合材料在牙科根管填充針之應用上極具潛力。機械性質方面，聚酯型聚胺酯做為基材之氧化鋅聚胺酯複合材料已超越臨床上常用的牙科根管填充針；熱性質方面也具有相似於臨床材料之熔點以及較低的比熱和熔化熱。因此在根管填充針方面，聚酯型聚胺酯做為基材之氧化鋅聚胺酯複合材料於根管治療臨床應用上之可能性極高。 牙科根管填充封填劑，本部份利用可見光硬化之胺酯壓克力樹脂做為基材，並使用三丙烯乙二醇雙丙烯酸酯做為稀釋單體，提高胺酯壓克力樹脂於牙科根管封填劑上之可行性，另外還使用經甲基丙烯酸羥基乙酯修飾之奈米二氧化矽做為填充料，兩者搭配使用形成胺酯壓克力及二氧化矽奈米混成材料。結果顯示，使用二異氰酸異佛爾酮之胺酯壓克力樹脂以七比三之重量比例和三丙烯乙二醇雙丙烯酸酯混合之樹脂黏度最適當，並以camphorequinone與對二甲胺基苯甲酸乙酯之混合最適合作為本系統樹脂之光起始劑，而百分之三重量百分濃度為最適當之起始劑濃度會使硬化後之樹脂具有最高的機械性質。此外，本實驗研發之胺酯壓克力及二氧化矽奈米混成材料在聚合後體積收縮量極小，純胺酯壓克力樹脂甚至在聚合後還有些微膨脹。操作性方面，胺酯壓克力樹脂及二氧化矽奈米混成材料之流動性質已通過ISO-6876流動性之最低標準。結果也指出，以胺酯壓克力樹脂及二氧化矽奈米混成材料和氧化鋅聚胺酯複合材料作為牙科根管填充封填劑和針，和牙齒的黏合度也較一般臨床使用之材料高。由掃描式電子顯微鏡對於胺酯壓克力及二氧化矽奈米混成材料和齒壁黏合情形做分析，發現胺酯壓克力及二氧化矽奈米混成材料可以流入牙根管壁上的牙小管並在其中硬化。最後洛華盛的混攙使胺酯壓克力混成材料在硬化後具有抗菌性。因此在根管填充封填劑方面，胺酯壓克力與二氧化矽奈米混成材料未來於臨床治療上之可能性極高。The purpose of this study was to develop a novel polymer-based root canal obturation material. Thermal polyurethane (TPU) was synthesized from polyester-type polyol, and zinc oxide (ZnO) was added into TPU as filler to form the ZnO/TPU composite. The mechanical properties, thermal properties and specific heat of the ZnO/TPU composite were investigated and compared to gutta-percha and Resilon in this research. Results showed that tensile strength and modulus of the ZnO/TPU composites can both be higher than gutta-percha and Resilon. Enthalpy change of the ZnO/TPU composite during phase transition is near gutta-percha but is lower than Resilon. There is no significant difference in melting point among ZnO/TPU composite, gutta-percha and Resilon. Specific heat of the ZnO/TPU composite is near gutta-percha but is lower than Resilon. It is found that no matter in mechanical properties or thermal properties; ZnO/TPU composite has great potential in the root canal filling material. For the sealer resin part, visible-light photopolimerizable urethane-acrylate oligomer was synthesized and mixed with dilute monomer to form UA/TPGDA resin. The mechanical properties, relative molecule weight, viscosities, conversions, polymerization shrinkage, bonding strength, interface between sealer and dentin and antibacterial properties UA/TPGDA resin were investigated in this research. Results indicate that the viscosity of UA/TPGDA resin can be altered by the TPGDA content. The photoinitiator for UA/TPGDA (7/3 by wt.) is the mixture of camphorquinone and ethyl 4-dimethylaminobenzoate (1/2 by wt.) with concentration 3 phr. As for polymerization shrinkage, the UA/TPGDA resin with no filler even expands 5.72×10-3 % after curing. Even the strain of the UA/TPGDA (7/3 by wt.) resin with 40% filler content after curing is only -7.26×10-2 %. As for bonding strength, results show that bonding strength of the UA/TPGDA (7/3 by wt.) with 40wt% HEMA-modified nano-SiO2 and Composite H3 which were used as sealer and cone is the highest of all other groups of sealer and cone. From SEM photographs, urethane-acrylate based sealer with 40% filler is able to flow into dentin tube and be cured in side the tube and be mixed well. Furthermore, UA/TPGDA resin becomes antibacterial because being blended with chlorhexidine. It is found that visible-light curable urethane-acrylate oligomer has great potential in the root canal filling material sealer.Contents Abstract in Chinese I Abstract III Contents V List of Table VIII List of Figure IX Chapter 1. Introduction 1 1-1 Introduction of root canal obturation material 1 1-2 History of root canal material 3 1-3 Polyurethane 5 1-4 Light polymerizations 7 1-4-1 Mechanism of chain-growth polymerization 7 1-4-2 Polymerization 10 1-5 Light curable oligomers 13 Chapter 2. Application of Zinc Oxide/ Polyurethane Composite in Dental Root Canal Obturation Cone Material 14 2-1 Material and methods 14 2-1-1 Chemicals 14 2-1-2 Measurements 15 2-1-3 Procedure to Synthesize TPU and Preparation of TPU/ZnO Composite 16 2-1-4 TGA analysis 17 2-1-5 Mechanical properties analysis 17 2-1-6 Thermal properties analysis 17 2-1-7 Specific heat analysis 18 2-2 Results 19 2-2-1 FT-IR analysis 19 2-2-2 Mechanical properties analysis 19 2-2-3 Thermal properties analysis 20 2-2-4 TGA analysis 20 2-2-5 Specific heat analysis 21 2-3 Discussion 22 2-3-1 FT-IR analysis 22 2-3-2 Mechanical properties analysis 22 2-3-3 Thermal properties analysis 24 2-3-4 TGA analysis 25 2-3-5 Specific heat analysis 25 Chapter 3. Application of Visible-light Curable Urethane-acrylate in Dental Root Canal Obturation Sealer 34 3-1 Material and methods 34 3-1-1 Chemicals 34 3-1-2 Measurements 37 3-1-3 Procedure to synthesize urethane-acrylate 39 3-1-4 GPC analysis 40 3-1-5 Viscosity analysus 40 3-1-6 Conversions analysis 40 3-1-7 Mechanical properties analysis 41 3-1-8 Polymerization shrinkage analysis 41 3-1-9 Curing depth analysis 42 3-1-10 Flow analysis 42 3-1-11 Bonding strength analysis 43 3-1-12 SEM analysis 45 3-1-13 Antibacterial analysis 45 3-2 Results 47 3-2-1 Chemical reaction of urethane-acrylate synthesis 47 3-2-2 GPC analysis 47 3-2-3 Viscosity analysis 48 3-2-4 Selection of photoinitiator through conversion analysis 48 3-2-5 Selection of photoinitiator concentration through conversions and mechanical properties of UA/TPGDA resins 48 3-2-6 Polymerization shrinkage analysis 49 3-2-7 Curing depth analysis 50 3-2-8 Flow & viscosity analysis 50 3-2-9 Bonding strength analysis 51 3-2-10 SEM analysis 51 3-2-11 Antibacterial analysis 52 3-3 Discussion 53 3-3-1 FT-IR analysis 53 3-3-2 GPC analysis 53 3-3-3 Selection of photoinitiator through conversion analysis 54 3-3-4 Selection of photoinitiator concentration through conversions and mechanical properties of UA/TPGDA resins 55 3-3-5 Polymerization shrinkage analysis 56 3-3-6 Curing depth analysis 56 3-3-7 Flow & viscosity analysis 57 3-3-8 Bonding strength analysis 59 3-3-9 SEM analysis 59 3-3-10 Antibacterial analysis 60 Chapter 4. Conclusions 77 Reference 79 CV for Author -1- List of Table Table 2-1 Material designations and mechanical properties of ZnO/TPU composites, gutta-percha, and Resilon 27 Table 2-2 Thermal properties of Composite H3, gutta-percha, and Resilon 27 Table 3-1 Viscosity of urethane-acrylate with various TPGDA contents 62 Table 3-2 Mechanical properties of UA/TPGDA (7/3 by wt.) with various photoinitiator (CQ+EDMAB) contents 62 Table 3-3 Curing depth of UA/TPGDA with various filler contents 63 Table 3-4 Flow & viscosity of UA/TPGDA with various filler contents 63 Table 3-5 Bonding strength of various groups of root canal obturation cone and sealer 64 Table 3-6 Antibacterial of various groups of root canal obturation cone and sealer 64 List of Figure Figure 2-1 Reaction equipment 28 Figure 2-2 Experimental process 29 Figure 2-3 Synthesis of TPU 30 Figure 2-4 FTIR spectrum of the synthesis of the TPU 31 Figure 2-5 DSC diagram of Composite H3, gutta-percha and Resilon 31 Figure 2-6 TGA diagram of Composite H3, gutta-percha and Resilon 32 Figure 2-7 Specific heat capacity for Composite H3, gutta-percha and Resilon 32 Figure 2-8 Melting points and enthalpy changes for Composite H3 matrix, gutta-percha matrix and Resilon matrix 33 Figure 3-1 Experimental process 65 Figure 3-2 Synthesis of TPU 66 Figure 3-3 Equipment to measure curing depth 67 Figure 3-4 Process to measure flow through ISO-6876 method 67 Figure 3-5 Process to measure bonding strength 68 Figure 3-6 FTIR spectrum of the synthesis of the TPU 69 Figure 3-7 GPC diagram of urethane-acrylate (HDI, PBA2000) and PBA2000 69 Figure 3-8 GPC diagram of urethane-acrylate (IPDI, PBA2000) and PBA2000 70 Figure 3-9 GPC diagram of urethane-acrylate (HDI, PBA1000) and PBA1000 70 Figure 3-10 GPC diagram of urethane-acrylate (IPDI, PBA1000) and PBA1000 71 Figure 3-11 GPC diagram of urethane-acrylate (HDI, PBA500) and PBA500 71 Figure 3-12 GPC diagram of urethane-acrylate (IPDI, PBA500) and PBA500 72 Figure 3-13 Conversions of UA/TPGDA (7/3 by wt.) with various photoinitiators 72 Figure 3-14 Conversions of UA/TPGDA (7/3 by wt.)with various photoinitiator contents 73 Figure 3-15 Polymerization shrinkage of UA/TPGDA (7/3 by wt.) with various filler contents 73 Figure 3-16 Sketch of calculation of relationship between viscosity and flow value 74 Figure 3-17 Bonding strength with various groups of root canal obturation sealer and cone 74 Figure 3-18 SEM of interfaces between UA/TPGDA (7/3 by wt.) with 40wt% HEMA-modified nano-SiO2 (sealer) and Composite H3 (cone) or dentin 75 Figure 3-19 Log of CFU in colony plotted as function of time with various chlorhexidine contents in cured UA/TPGDA (7/3 by wt.) with 40wt% filler 76 Figure 3-20 Log of CFU divided by CFU0% in colony plotted as function of time with various chlorhexidine contents in cured UA/TPGDA (7/3 by wt.) with 40wt% filler 7