In Vitro Evaluation Of Zirconia Surface Treatments On The Shear Bond Strength Of Veneering Ceramic

Objective:To study different sandblasting conditions and different surface coarseningmethods affecting the shear bond strength between zirconia and veneering ceramic,provide suitable pretreatment method for technical processing zirconia.Method:1. The method of making zirconia test pieces:Zirconia ceramic block were cut, dense sintered into8mm×8mm×3mm（±0.02）186blocks, randomly divided into31groups, six blocks in each group.2. Groups:â‘´Combined on condition that the sandblasting powder particles of different（A₁=75μm、 A₂=110μm、 A₃=150μm）, the sandblasting pressure （B₁=0.2MPa、B₂=0.4MPa、B₃=0.6MPa） and sandblasting time （C₁=10s、C₂=20s、C₃=30s）,forexample A₁B₁C₁、A₁B₁C₂、A₁B₁C₃、A₁B₂C₁etc were divided into27groups, then27groups were sandblasted in different conditions.⑵According to different surface coarsening methods,the experiments dividedinto control group、grinding group、sandblasting group、grinding and sandblastinggroup.Control group:with no handling;grinding group:diamond bur grinding underwater-spray jet;sandblasting group:Al2O3sandblasting （110μm,0.4MPa,20s）;grindingand sandblasting group:diamond bur grinding under water-spray jet+aluminium oxidesandblasting （110μm,0.4MPa,20s）.3. Experimental determination:One block of each group was selected for observing the surface topographies byscanning electron microscope.The remaining specimens were processed by sinteringinto cylindrical veneering ceramic that was diameter of3mm and height of3mm onzirconia surface, then were made of standard shear bond test specimen（14mmdiameter,5mm height）.Used electronic universal dynamometer to measure maximum shear bond stress（N）, calculated the shear bond strength（MPa）, observed the interfaceshear damage of specimen and recorded the destruction form, analyzed the obtaineddata by using the statistical software SPSS16.0.Result:1. Analyzed the value of the shear bond strength test on different sandblastingconditions by three factors factorial analysis, the result shows:â‘´The main effect of factor "particle" had statistical significance（P<0.01）,threekinds of sandblasting powder with different particle was significant on SBS（ShearBond Strength）.⑵The main effect of factor "pressure" had statistical significance（P<0.01）,three kinds of sandblasting powder with different pressure was significant on SBS.⑶The main effect of factor "time" had statistical significance（P<0.01）, threekinds of blasting powder with different time was significant on SBS.â‘·There was interaction between the factor "particle" and the factor "pressure"（P<0.05）.⑸There was interaction between the factor "particle" and the factor "time"（P<0.05）.⑹There was interaction in the three factors （P<0.01）.2. Analyzed the value of shear bond strength test on different sandblastingconditions by One-way ANOVA and compared each two groups by LSD test.â‘´To "particle" for the analysis factor, when the sandblasting conditions wereB₂C₃、B₃C₁、B₃C₂,the SBS of group A₁was the maximum; when the sandblastingcondition was B₂C₂、B₃C₃,the values of SBS both group A₁and A₂were the same andmore than group A₃; when the sandblasting conditions were B₁C₃、B₂C₁,the SBS ofgroup A₃was the maximum.⑵To " pressure " for the analysis factor, when the sandblasting condition wasA₃C₃,the SBS of group B₁was the maximum; when the sandblasting conditions wereA₁C₂、A₁C₃、A₂C₂、A₂C₃、A₃C₁、A₃C₂,the SBS of group B₂was the maximum; Whenthe sandblasting condition was A₂C₁, the values of SBS both group B₂and B₃werethe same and more than group B₁;when the sandblasting condition was A₁C₁,the SBSof group B₃was the maximum. ⑶To " time " for the analysis factor, when the sandblasting conditions wereA₁B₃、A₂B₃、A₃B₃,the SBS of group C₁was the maximum; when the sandblastingconditions were A₁B₂、A₂B₂、A₃B₂,the SBS of group C₂was the maximum; when thesandblasting condition was A₃B₁,the SBS of C₃was the maximum.3. The difference between4groups of blocks（P<0.01）,the shear bond strengthof sandblasting group was the maximum（P=34.10±0.97MPa）,and the shear bondstrength of grinding group was the minimum（P=24.84±0.21MPa）. Compared eachtwo groups by LSD,control group> grinding group（P<0.01）;sandblasting group>control group （P<0.01）; sandblasting group> sandblasting+grinding group（P<0.01）;sandblasting+grinding group> control group（P<0.05）.4. Failure mode was the main interface failure between zirconia and veneeringceramic.Conclusion:1. Shear bond strength was the maximum when zirconia be sandblasted for20swith75μm and110μm alumina at0.4Mpa pressure in this vitro study.2. The shear bond strength between zirconia and veneering ceramic was theminimum when sandblasted for30s with150μm alumina at a pressure of0.6MPa inthis vitro study.3. Grinding treatment decreased the shear bond strength between zirconia andveneering ceramic.Zirconia surface avoids grinding processing, if it have beengrinded then should be sandblasted.