| Purpose:Through the experiment in vitro,different surface treatments were used to treat the surface of cobalt-chromium alloy fabricated by Selective Laser Melting(SLM)technology,and the shear bond strength between SLM cobalt-chromium alloy and the three cements which were commonly used in clinic after undergoing various surface treatments was evaluated.Methods :1.Making samples of Co-Cr alloy fabricated by SLM:Based on experimental requirements,bego cobalt-chromium powder was employed in the laser melting machine to prepare 57 cuboid cobalt-chromium alloy samples intending to measure10 mm by 10 mm by 2mm.2.First treatment of SLM Co-Cr alloys.Under the running water,57 SLM cobalt-chromium alloy samples were successively polished by SiC waterproof abrasive papers with grits of #400,#600,#800 and #1000 for 100 times under the same pressure,after douching and blow-drying,scanning electron microscope was used to observe the surface morphology of a sample randomly selected from the above samples and magnified by 2000 times.Then the polished 57 SLM cobalt-chromium alloy samples were sandblasted for 10 seconds by pen-based sand-blasting machine.After blasting,these SLM cobalt-chromium alloy samples were cleaned ultrasonically in distilled water for 10 minutes and naturally dried at room temperature for 24 hours as standby.3.The production of standard test block of SLM cobalt-chromium alloy.In the mould,the above treated SLM cobalt-chromium alloy samples were embedded with autopolymerizing acylic resin,with the treated side being exposed,then they are manufactured as standard test blocks with diameter being 14 mm and thickness being 4mm..4.Groups:Fifty-four standard test blocks were randomly divided into A,B,C three groups,each group has 19 pieces.Group A was not treated,group B was treated with silane coupling agent,group C was treated with 9.6% hydrofluoric acid.In the A,B,C three groups are randomly selected a block from each group,than their surface morphologies were observed under electron microscope.All the rest of the A,B,C three groups,each group was randomly divided into three subgroups: A1,A2,A3,B1,B2,B3,C1,C2,C3,a total of 9 subgroups.Then A1,B1,C1 are bonding with glass ionomer cement,A2,B2,C2 are bonding with resin reinforced glass ionomer cement,and A3,B3,C3 are bonding with resin cement.All the bonding experiments were performed according to the strict requirements,and they all had the same bonding area.Then put them in a constant temperature water bath with artificial saliva for 24 hours at a temperature of 37 degrees Celsius.5.Experimetal determination:These specimens were tested by electronic universal testing machine,and the maximum force was calculated when the fracture was broken.The shear strength was calculated by P=F/S.The failure modes of each block were observed.The results were statistically analyzed with IBM SPSS Statistics 19.0 software.Results:1、These two factors,surface treatment methods and the types of cement are interaction.SLM Co-Cr alloy was treated by sandblasting and then using silane coupling agent to bond with resin cement have the strongest shear strength in this experiments.2、Take the three surface treatments(sandblasting,sandblasting+silance coupling agent,sandblasting+hydrofluoric acid etching)as analysis factors:1.In the condition of using glass ionomer cement,there was no significant difference in shear strength between the three surface treatments(P>0.05).2.In the condition of using Resin reinforced glass ionomer cement,there was no significant difference in shear strength between the three surface treatments(P>0.05).3.In the condition of using resin cement case,the surface treatment of sandblasting + silane coupling agent has greater shear strength than the surface treatment of sandblasting(P<0.05),the surface treatment of sandblasting + silane coupling agent has greater shear strength than the surface treatment of sandblasting+hydrofluoric acid etching(P<0.05),but there is no statistical difference between the surface treatment of sandblasting and sandblasting+hydrofluoric acid etching(P>0.05).3、Take the three cements(glass ionomer cement,resin reinforced glass ionomer cement,resin cement)as analysis factors:1.In the surface treatment of sandblasting for SLM Co-Cr alloy,the resin cement has greater shear strength than glass ionomer cement(P<0.05),the resin cement has greater shear strength than resin reinforced glass ionomer cement(P<0.05),but there is no statistical difference between glass ionomer cement and resin reinforced glass ionomer cement(P>0.05).2.In the surface treatment of sandblasting and silane coupling agent for SLM Co-Cr alloy,resin reinforced glass ionomer cement has greater shear strength than glass ionomer cement while those in group resin cement were the biggest.(P<0.05)3.In the surface treatment of sandblasting+hydrofluoric acid etching for SLM Co-Cr alloy,resin reinforced glass ionomer cement has greater shear strength than glass ionomer cement while those in group resin cement were the biggest.(P<0.05)4、Observe the failure mode of bonding interface.The bond failure mode experiment of SLM Co-Cr alloy with glass ionomer cement or with resin reinforced glass ionomer cement are mainly interface failure,with resin cement bonding experiment is mainly mixed failure.Conclusion:For the Co-Cr alloy fabricated by selective laser melting,with the surface treatment of both sandblasting and silane coupling,and than choose resin cement to bond is the best. |
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