| Objective: Hyramic is a kind of resin nano ceramic independently developed by UPCERA in Shenzhen,China.It’s a kind of polymer resin matrix embedded with nanoceramic particles.It combines physical and mechanical advantage of the ceramic,which improves the bending performance and wear resistance of the composite resin.It has lower rigidity,brittleness,hardness,and high flexibility,bending strength and wear resistance potential under the pressure load.It can be directly applied to clinical tooth defect repair,and thus efficient time-saving workflow after polishing.The purpose of this study is to analyze the influence of thermal cycling aging on the shear bond strength(SBS)of hyramic to the resin cement after sandblasting with different particle sizes of alumina by in vitro experiments,and to compare it with Lava Ultimate,so as to provide experimental basis for the clinical application of Hyramic as indirect restorations.Methods: Hyramic and Lava Ultimate was cut into 6mm×5mm×5mm blocks,of which27 hyramic blocks and 9 Lava Ultimate blocks were selected.Hyramic blocks were randomly divided into 3 groups for different surface pretreatment:(1)untreated Hyramic group(NT);(2)30um alumina sandblasting treatment group of Hyramic(H1);(3)50um alumina sandblasting treatment group of Hyramic(H2);(4)50um alumina sandblasting treatment group of Lava Ultimate(LU).Each group select one block to observe the surface morphology under scanning electron microscopy.The remaining blocks were coated with silane coupling agent on the bonding surface and then placed with cylindrical molds(n=32).Multilink N resin cement was filled into these molds.After being light cured,all finished specimens were stored in 37℃ distilled water for 24 hours.The cylindrical molds was removed with a sharp scalpel after the storage period,and then half of the specimens were randomly selected for the SBS test,while the other half were submitted to thermal cycling(5000cycles,5-55℃)before the SBS test(n=16).Data were statistically analyzed with one-way analysis of variance(ANOVA)and nonparametric test(a=0.05).Results: For Hyramic,the bonding strength of sandblasted group was significantly higher than that of untreated group(P<0.05),and the bonding strength of 30 um alumina sandblasting group was higher than that of 50 um alumina sandblasting group,but the difference was not significant(P > 0.05).Besides,the bond strength of Hyramic sandblasted with 30 um particle size of alumina was higher than that of Lava Ultimate after sandblasted with 50 um particle size of alumina before aging(P<0.05),but there was no statistical difference between the two groups after aging(P > 0.05).There was no significant difference in the bonding strength between the group with 5000 times of thermal cycling compared with the group without thermal cycling(P>0.05).Conclusion: 1.Sand blasting significantly improves the bonding strength of Hyramic and resin cement,and the bonding strength of Hyramic treated by 30 um alumina sandblasting is higher.However,when the particle size of sandblasting is too large,the bonding strength of Hyramic will be reduced.2.Thermal cycling of 5000 times have no significant influence on the bond strength of Hyramic and Lava Ultimate. |
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