| Objective:The polyether modified silicone oil as a wetting agent,the novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl as an antibacterial agent,were both added into the self-made silicone rubber impression material,and the effect of their dosages on the properties of silicone rubber was investigated.Therefore,a novel type of silicone rubber impression material with both hydrophilic and antibacterial property was prepared to better meet the clinical demand,and further promote the application and development of silicone rubber materials in dental field.Method:Part 1:Select the four parameters of tensile strength,elongation at break,tear strength and hardness as the indicators for the mechanical properties test.The effects of different viscosity of vinyl silicone oil and different content of hydrogen-containing silicone oil,fumed silica,kaolin and vinyl MQ silicone resin on the mechanical properties of silicone rubber were discussed,so as to determine the optimal content of each component and obtain the basic formula of addition silicone rubber impression materialPart 2:The polyether modified silicone oil with different mass fraction of 0%(blank control),2%,4%,6%,8%and 10%were added into the self-made silicone rubber impression materials by means of bulk modification,in order to give them hydrophilicity.The static contact angles of t=0,t=60s,and t=120s were measured by the sessile drop method.The tensile strength,elongation at break,tear strength and hardness of the materials were measured.The detail reproducibility and dimensional stability of the materials were tested by the replication of special mold surface marking lines and the linear dimensional changes after 1h,24h,1 week and 1month.The experimental results were statistically analyzed.Part 3:The novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl was synthesized and added into the hydrophilic silicone rubber impression materials with different mass fraction of 0%(blank control),1%,2%,3%,4%and 5%,in order to give them antibacterial.Fourier transform infrared spectroscopy(FTIR)and scanning electron microscope(SEM)were used to analyze the chemical structure and observe surface morphology of the antibacterial filler.The antibacterial property and cytotoxicity were detected by thin-film adhesion method and cell counting kit-8(CCK-8)method.Meanwhile,the wettability,mechanical properties,detail reproducibility and dimensional stability were also measured.The experimental results were statistically analyzed.Result:1.The addition silicone rubber was prepared with 5000 mPa·s vinyl silicone oil of 100 PHR,0.8%hydrogen silicone oil of 6 PHR,fumed silica of 25 PHR,kaolin of 45 PHR and vinyl MQ silicone resin of 10 PHR.Its tensile strength was 4.20 MPa,elongation at break was 118.19%,tear strength was 5.02 kN/m,hardness was 57.23 Shore A,which showed good mechanical properties.2.When 6wt%polyether modified silicone oil was added into the silicone rubber,the contact angle decreased significantly(P<0.05).The contact angles at t=0,t=60s,and t=120s were(75.36 ± 3.20)°,(65.12± 2.96)° and(61.15±2.94)°,which showed good wettability.The tensile strength was(3.77± 0.20)MPa,the elongation at break was(154.79 ± 13.90)%,the tear strength was(4.74± 0.26)kN/m,and the hardness was(53.21 ± 2.29)shore A.There was no significant difference between this group and the blank control group(P>0.05).Silicone rubber can completely replicate the three marking lines with the width of 20 μm,50 μm and 75 μm on the surface of the special mold.The linear dimension change rates at 1h,24h,1week and 1 month after impression was taken were(0.10±0.02)%,(0.18±0.03)%,(0.75±0.07)%,(1.89±0.18)%.Except that the linear dimensional change rate after 1 month was more than 1.5%in the standard,the others were less than 1.5%in the standard,and there was no significant difference compared with the blank control group(P>0.05).3.FTIR analysis showed that both the quaternary ammonium salt and the silane coupling agent were successfully grafted onto the surface of nano-SiO2;SEM showed that the antibacterial filler treated by coupling agent had good compatibility with silicone rubber matrix,and the distribution was relatively uniform.When 4wt%antibacterial filler was added,the antibacterial rate reached 95.26%,which had good antibacterial property.After co-cultured with human gingival fibroblasts(HGFs)for 24h,48h and 72h,there was no significant difference in optical density(OD)compared with the negative control group(P>0.05).The cytotoxicity grade was level 0 or 1,indicating that the silicone rubber had no obvious cytotoxicity.The contact angles at t=0,t=60s,and t=120s were(75.88±2.56)°,(66.21 ± 2.08)° and(62.59±2.01)°,which was no significant change compared with the blank control group(P>0.05).The tensile strength was(3.42±0.25)MPa,elongation at break was(138.95±8.33)%,tear strength was(4.62±0.15)kN/m,and hardness was(52.12 ±1.72)shore A.There was no significant difference between this group and the blank control group(P>0.05).Silicone rubber can completely replicate the three marking lines with the width of 20 μm,50 μm and 75 μm on the surface of the special mold.The linear dimension change rates at 1h,24h,lweek and lmonth were(0.12±0.02)%,(0.17±0.04)%,(0.70±0.09)%,(1.81±0.13)%.Except that the linear dimension change rate after 1month was more than 1.5%in the standard,the others were less than 1.5%in the standard,and there was no significant difference compared with the blank control group(P>0.05).Conclusion:In this study,a novel silicone rubber impression material with both hydrophilic and antibacterial property was successfully prepared.When the mass fraction of polyether modified silicone oil was 6%and the new inorganic antibacterial filler was 4%,the contact angle of 75.88° and antibacterial rate of 95.26%could be obtained.At the same time,the silicone rubber also had good mechanical properties,detail reproducibility,dimensional stability and biological safety. |
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