Effects Of Different Surface Treatments On Bonding Strength And Durability Of Zirconia Ceramics And Resin Cements

Objectives:In this study,three different treatment methods were used to improve the surface of zirconia ceramics,including sandblasting,coating with 10-MDP primer and lithium disilicate ceramic coating.We will explore the application of these methods in improving the surface properties of zirconia and evaluate their bond strength and aging resistance in resins and ceramics.At present,there are few research data on the pretreatment of lithium disilicate ceramic coating technology.In this study,it is compared with other two surface treatment methods and combined with two different types of resin cements,so as to provide a certain theoretical basis for the selection of clinical bonding schemes for zirconia ceramics.Methods:In this experiment,136 pieces of 10 mm x 10 mm x 2mm polished Wieland Dental zirconia were divided into 4 groups according to the surface treatment methods:Group A(blank control group),Group B(sandblasting group),group C(sandblasting and coated with primer Z-PRIME plus),group D(sandblasting and sintered lithium disilicate coating and HF acid etching).After the pretreatment,two pieces were randomly selected from each group for observation by scanning electron microscope(SEM),analysis by EDS and contact angle test.The remaining pieces exposed their treatment surface and were embedded in the self-coagulating resin,and two different types of resin cements,NX3 Nexus and C1earfi1 SAC,were used to bond with the pre-prepared resin rods.The prepared test pieces were stored in a 24 h 37 ℃ water bath or a 24 h 37 ℃ water bath+5000 cold and hot cycles respectively.After being taken out,the shear bond strength(SBS)was tested on a mechanical universal testing machine,and the failure mode of each group of test pieces was observed using a body microscope.SPSS 25.0 software was used to analyze the experimental data.Twofactor analysis of variance and multiple comparison among LSD groups were used to compare the measured data.Results:1.SEM results show that the surface roughness of each group of test pieces after different surface treatments has increased compared with the blank control group.Sandblasting could make the ceramic surface form irregular pit crister-like structures,and the primer coating substrate could fill in some pits.However,the specimens with sintered lithium disilicate coating on the surface which the glass phase were dissolved after acid etching,exposing a large number of regular crystal structures.2.EDS results showed that compared with the blank control group,sandblasting increased a small amount of Al element on the surface of the specimens,and coating substrate Z-PRIME plus resulted in a large amount of C element on the surface of the specimens,while Si element and F element from the acid etching agent were detected on the surface of the specimen with sintered lithium disilicate coating.3.The results of contact angle test showed that compared with the blank control group,the water contact angle of the specimens with different surface treatment in each group decreased(P < 0.05).The order from small to large is lithium disilicate coating group,bottom coating group,sandblasting group and control group.4.SBS results show that the bonding property of resin cement Clearfil SAC to ceramics is better than that of resin cement NX3 Nexus.Among the specimens with different surface treatment of the same resin cement,the ceramic coated with lithium disilicate has the highest bond strength(11.35MPa),followed by the bottom coating group and sandblasting group.After 5000 hot and cold cycles,the SBS value of lithium disilicate coating did not decrease significantly(P >0.05),but it decreased most significantly in the primer group(P < 0.05).5.The results of failure mode analysis showed that there was no cohesive failure mode in each group observed under the microscope,and all specimens were adcohesive failure mode and adhesive failure mode.When using cement NX3 Nexus,the proportion of bonding failure mode was higher than that of cement C1earfi1 SAC,and the proportion of adhesive failure mode still increased after5000 cycles of hot and cold.Conclusions:1.The use of different surface treatment methods or different types of resin cement will affect the bonding strength between ceramics and resin.2.In this study,the three surface treatment methods have a positive effect on the bonding strength between ceramics and resin,and the effect of lithium disilicate coating pretreatment combined with resin cement Clearfil SAC is the best.3.After hot and cold cycles,the durability of zirconia ceramics bonded by sandblasting and primer treatment is not good.Lithium disilicate coating pretreatment can provide more stable and lasting bonding strength for zirconia ceramics.It is expected to solve the problem of bonding effectiveness of zirconia materials,but clinical experiments are still needed to verify its clinical effect.