Effect Of Different Surface Treatments On The Bonding Strength Between Dental Glass Ceramics And Resin Cements

Objective:To investigate the effects of different surface treatment methods on the bond strength between dental glass ceramics and resin cements,and to provide theoretical basis for clinical work.Method:This study was divided into two parts.Part 1:The standard lithium cereamic were divided into 8 groups(N=16),and the 4.5%hydrofluoric acid etching time was Os,10s,20s.,30s,40s,60s,120s,180s,and then each group was divided into two treatment groups,one of which was coated with a coupling agent and the other was not coated.Bonding test pieces were prepared and bond strength test was performed to record the bond strength;the fracture mode was observed;and the surface morphology of the test pieces after acid etching was observed by electron microscopy;the results were statistically analyzed.Part 2:The standard litihium ceramic were divided:into two groups,onegroup was not etched,and the other group was etched with 4.5%hydrofluoric acid for 30 s,and then the following treatments were respectively perfonned:room temperature group,60 ?hot air group,100 ? hot air group,the bonded test pieces were prepared and tested for bonding strength,and the bond strength was recorded;the fracture mode was observed;and the samples after the application of the coupling agent were characterized by infrared spectrum analysis;the results were statistically analyzed.Results:1.Regardless of whether or not the coupling agent was used,the maximum adhesion strength values were obtained for the two groups of samples after hydrofluoric acid etching for 30s.The SBS value of the No-coupling-agent group was 20.27 MPa,and the SBS value of the coupling-agent group was 25.91 MPa,there was a significant difference between two groups(P<0.05).When the hydrofluoric acid etching time is too long,the bonding strength between the ceramic and the resin cement is obviously decreased,and the SEM shows the surface morphology of the over-etched surface.2.Regardless of whether it is acid etched or not,the maximum SBS value can be obtained by 60 ? hot air treatment after coating the coupling agent,wherein the unetched group is 27.05 MPa and the acid etching group is 28.70 MPa;when the heat treatment temperature is raised to 100 ?,the bond strength decreased significantly(P<0.05);Infrared spectroscopy analysis showed that the surface of the 60? hot air treatment group had the highest silicon oxide bond formation,followed by 100? and the lowest room temperature.Conclusion:1.Under the experimental conditions,for lithium porcelain,the optimum etching time of 4.5%hydrofluoric acid is 30s.If the etching is applied for 30s,the bonding strength of silane coupling agent can be more ideal.2.Under the condition of heat treatment,the silane coupling agent can obtain the ideal SBS value without the hydrofluoric acid etching,which suggests that we can remove the step of hydrofluoric acid etching during the repair treatment;under the 60 ? hot air condition,the bond strength between lithium porcelain and resin is the highest,exceeding the 100? hot air treatment group,which may be related to the self-polymerization of the coupling agent.