The Research For The Effect Of Cryogenic Treatment On Bond Strength Of Porcelain To Dental Casting Pure Titanium

Objective:The purpose of this study was to investigate the effect of cryogenic processing technique on casting pure titanium metal-porcelain bonding strength,and enable to seek for new techenologies improving the bond strength between pure titanium and porcelain,which can be excepted to provide the theoretical basis for increasing surviveship of pure titanium based PFM crown.Materials and Methods:The test samples were prepared based on ISO 9693:1999. After producting,all pure titanium casting specimens were randomly divided into three groups: the control group(A),cryogenic treatment before porcelain-sintering group(B) and cryogenic treatment after porcelain-sintering group(C). And then all specimens were processing cryogenic treatment and porcelain-sintering respectively. The electronic universal testing machine was used to measure the three-point bending test for most specimens, and conducting statistically analysis to the data. Observing the microstructure of titanium-porcelain bonding interface of titanium porcelain specimens in each groups under a scanning electron microscope and analysing the elements distribution on the binding interface.Results:Three-point bending test results: Mean bond strength values and standard deviations of each group are as follow: group A(30.18±5.48MPa), group B(31.02±5.44MPa), group C(36.46±4.50MPa). ANOVA and S-N-K multiple comparison tests were used to analyzethe data at a 5% probability level.ANOVA test results showed significant overall differences among bond strengths of the metal-porcelain combinations(P<0.05). S-N-K multiple comparison test revealed that the cryogenic treatment after porcelain-sintering group had a significantly higher bond strength than the other combinations(P <0.05). The bond strength of cryogenic treatment before porcelain-sintering group was higher than the control group,however, this difference was not statistically significant(P> 0.05).Gross appearance of titanium porcelain fracture surface: In cryogenic treatment after porcelain-sintering group, more residual ceramic block was observed on titanium de-bonding surfaces, and on ceramic de-bonding surface can see the black oxide film and white porcelain pieces were displayed in patchy; In the control group and cryogenic treatment before porcelain-sintering group, there was almost no residue porcelain pieces can be observed on titanium de-bonding surface, and on porcelain de-bonding surface can see a black oxide film and few punctate porcelain residues;SEM observation: the microstructure of all groups showed the chimeric closely contact in interface;EDS analysis results: the main elements distribute titanium porcelain interface were Ti、Si、O、Na. And the elements were mutual diffusion, presenting gradually changing trends in the interface.Conclusion:cryogenic treatment technology can be enable to inprove bonding strength of pure titanium porcelain crown.