Experimental Study On The Bond Strength Of Pure Titanium-porcelain Treated With Different Concentration Of Silane Coupling Agent

Objective: This experiment used different concentrations of silane coupling agent to treat the surface of pure titanium to make standard titanium-porcelain specimens of the same size.The three-point bending test method was used to detect the bonding strength between pure titanium and porcelain.The combinative interface features of titanium and porcelain was observed by scanning electron microscopy to provide the experimental evidence of enhancing the bonding ability between pure titanium and porcelain.Method:1.Prepare specimens:The specimens were cutted by TA2 titanium plates into 50 equal-sized and identically shaped test pieces and divided into 5 groups,each group of 10.One group was selected as the control group(group A)without any treatment,and the remaining samples were placed in 10 mol/l NaOH for pretreatment,the treatment time was 5 min.One of the groups was selected as a sample for the control group(Group B)which was pretreated with only NaOH solution.Each group specimens of the remaining three experimental groups was put into the 8%,15%,and 33% three concentrations of the hydrolyzate for 10 min and then heated in air dry oven for 3 h.The temperature was set to 130 °C until the silane was aged and formed into a film.The ceramic powder is layered to the middle third of the pure titanium substrate and placed in a porcelain furnace and sintered according to a predetermined procedure.The size and thickness of the porcelain layer are the same as ISO9693,and the length X width X thickness is 8 X3 X1(in mm).The porcelain layer only sinters three parts,namely: Bonder porcelain,opaque porcelain,and dentin porcelain.2.Scanning Electron Microscopy(SEM): Two specimens from each group were used for scanning electron microscopy(10 in total).10 test specimens were respectively embedded in self-curing resin and cut horizontally in the central part to expose titanium-porcelain bonding cross-sections.The completed specimens with scanning electron microscopy were observed the microstructure of the interface between titanium and porcelain with the scanning electron microscopy.3.Bond strength test: The remaining specimens were tested with a universal tester for the bonding force between pure titanium and porcelain.The bonding strength and the average values was calculated according to the formula.4.Statistical analysis: The data obtained were analyzed statistically,and the test results were analyzed using Windows SPSS 23.0 statistical software.Differences among groups were compared using one-way analysis of variance.The overall differences were first compared,and then each group was compared.Test standard ?=0.05.Result:1.Three-point bending test results: The binding strength of group A without any treatment group was(24.71±4.36)MPa;the binding strength of group B NaOH solution treatment group was(32.53±9.23),Group C concentration of 8% silane coupling agent treatment of pure titanium binding strength was(33.72±5.39)MPa;Group D concentration of 15% silane coupling agent treatment of pure titanium binding strength was(46.33 ± 6.98)MPa;Group E concentration of 33% silane coupling agent treatment of pure titanium binding strength was(53.86 ± 5.12)MPa.The statistical analysis results showed that the results of the comparison between group B,C,D,E and group A were all statistically significant(P<0.05).There was a significant difference between the E group and the A group,indicating that the 33% silane coupling agent had the most significant effect on the surface of pure titanium.2.Electron microscopy observation results: In the A group(Fig.3),the interface between the titanium and porcelain was smooth and continuous,no oxide layer was observed,but some reaction layers were visible,cracks existed in the interface area,and cracks were large.The B group(Fig.4)has a more curved interface,reduced cracks,and a clear dividing line between titanium and porcelain.Group C(Fig.5)has another layer structure in the interface area,but the structure of this layer is relatively loose.In this area,the titanium and porcelain are embedded with each other,there is no clear demarcation,and cracks still exist between the titanium-porcelain.In the D group(Fig.6),the interface region of titanium-porcelain was embedded,and only tiny pores existed.In the E group(Fig.7),the titanium-porcelain were embedded to each other with tight bonding,no obvious boundary,no cracks and holes.Conclusion:1.Titanium surface treated with different concentrations of silane coupling agent can improve the titanium ceramic bonding strength.2.Titanium surface treated with 33% silane coupling agent had the highest bonding strength,followed by 15% silane coupling agent treatment and 8% silane coupling agent treatment.