Restoration Of Class Ⅱ With Aesthetic Composite Resin After The Dental Pneumatic Ultrasonic On The Edge In Vitro Study

Objectives We had conducted the orthogonal experiment with two kinds of composite resins,two kinds of bonding agents and two kinds of margin finishing methods.Through the experiment,we compared each group’s microleakage value and shear bonding strength value and explored influence factors of marginal microleakage of ClassⅡand shear bonding strength.We further compared the primary and secondary relation of these influence factors.We explored the tribological property of two kinds of composite resins and checked their compatibility with natural tooth enamel through friction and wear experiments.Methods 1 Three factors of orthogonal experiment:margin finishing method（A）,bonding agent（B）and composite resin（C）.Each factor had two levels:A₁（MANI TF-12 EF bur）,A2（KaVo SONICflex pneumatic ultrasonic finishing work tip）;B1（Xeno-V Plus bonding agent）,B2（ENA bond SE bonding agent）;C1（Ceram-X duo composite resin）,C₂（ENA HRi composite resin）.After collecting extracted molars and premolars,we evaluated how three factors（A,B and C）influenced microleakage and shear bonding strength by the orthogonal experiment,and selected the optimal combination.During the experiment,we measured enamel surfaces dealt with by means of both A₁ and A₂ with a surface roughness measuring instrument and observed surface morphology with SEM.2Friction and wear experiments:we used a MMW-11 friction and wear instrument to study friction and wear properties of Ceram-X duo and ENA HRi.Natural tooth enamel was a control group,Ceram-X duo and ENA HRi were experimental groups.We set the following parameters:testing force（40N）,rotating speed（100r/min）,cycle numbers（50000times）.The surface roughness and hardness of control group and experimental group was measured with the surface roughness measuring instrument and vickers hardness tester respectively.The mass loss was measured with electronic scales.The surface morphology was observed with SEM.Results 1 Group A₂B₂C₂ was the optimal combination.Because it’s microleakage value was minimum（50.65μm）and shear bonding strength value was maximal（22.66MPa）.The margin finishing method,bonding agent and composite resin all had influence on marginal microleakage of ClassⅡand shear bonding strength.There was statistically significant difference（P<0.05）.The enamel’s surface roughness processed with A₂ was smaller than that of A₁,there was statistically significant difference between them（P<0.05）.The surface morphology of the two groups was obviously different under SEM.2 After the experiment of friction,the wear mechanism among three groups was abrasive wear and adhesive wear under SEM.The wear degree of the enamel group was the lightest,ENA HRi resin group followed,Ceram-X duo resin group was the worst.We respectively analyzed the mass loss,surface roughness and hardness according to one-way ANOVA,there was statistically significant difference among three groups（P<0.05）,and among the different groups,P<0.05.Using correlation analysis between materials’ mass loss and hardness for each group（r=﹣0.998,︱r︱>0.8,P=0.043,<0.05）,significant negative correlation,so there were significant negative correlation between materials’ mass loss and hardness,with the increase of hardness,the mass loss decreases.Conclusions The margin finishing method,bonding agent and composite resin all play an important role on marginal microleakage of ClassⅡand shear bonding strength.There are three factors of microleakage classified by composite resin>bonding agent>margin finishing method.And the three factors of shear bonding strength are classified by bonding agent>margin finishing method>composite resin.KaVo SONICflex pneumatic ultrasonic finishing work tip was superior to extremely fine grain carborundum bur MANI TF-12 EF.ENA HRi resin was superior to Ceram-X duo resin.ENA bond SE bonding agent was superior to Xeno-V Plus bonding agent.The friction and wear property of ENA HRi resin was most matched with natural enamel.In addition,the ideal restoration effect also can be brought out by mixing different manufacturers’ composite resin and bonding agent.