| Resin-matrix ceramic is a new class of dental esthetic restorative material,consisting of a resin matrix filled with ceramic particles.Strictly speaking,resin-matrix ceramics do not belong to ceramics.However,they are regarded as a class of all-ceramic material since their mechanical properties,aesthetic properties,physical and chemical properties,indications are similar to traditional dental ceramics.The resin-matrix ceramic has the advantages of both resin and ceramic,also,they have similar elastic modulus to natural dentin and low wearing effect to natural teeth.In recent years,resin-matrix ceramic materials have been developed rapidly,new resin-matrix ceramic materials continue to appear and have been widely used in clinic.As a kind of indirect prosthesis commonly used in clinic,the bonding properties of resin-matrix ceramics have great influence on the clinical application.At present,there is still a lack of systematic and comprehensive research on resin-matrix ceramics.The chemical composition and microstructure of different resin-matrix ceramic materials are different,and the surface treatment methods are also different.The resin-matrix ceramic used in this study is resin nanoceramic(RNC),which is improved and strengthened by adding inorganic filler into resin matrix.At present,the effects of different surface treatment methods on the bonding strength of RNC have not been fully researched.As an efficient and clean surface treatment method,cold atmospheric plasma(CAP)has been used to improve the bonding properties of other all-ceramic dental materials.However,there is no evidence of its effect on resin-matrix ceramics.In order to improve the bonding strength of resin-matrix ceramics,and to explore the effect of CAP treatment on resin-matrix ceramics,this study evaluate the classic sandblasting and two kinds of CAP as surface treatment methods of RNC.The study investigated the physical and chemical properties changes after different surface treatments,and their influence on bonding strength.Objectives:To study the influence of different sandblasting conditions on the surface properties and bonding strength of RNC.To study the effects of CAP on the surface properties and bonding strength of RNC.To study the effects of different CAP treatment methods on the bonding strength and aging properties of RNC.Collectively,to find a suitable bonding treatment method for the resin-matrix ceramic used in this study and further guide its clinical usage.Methods:Part 1:Effects of different sandblasting conditions on the bonding properties of resin nanoceramicThe resin nanoceramic was processed into square specimens and randomly divided into six groups:control group,silane coupling agent group,group(0.1MPa 50?m),group(0.2MPa50?m),group(0.1MPa 110?m),group(0.2MPa 110?m).The surface microstructure,surface roughness and surface water contact angle of each sample were observed.The effects of different sandblasting conditions on physical and chemical properties of the material surface were analyzed.After the resin was bonded to the surface of the specimens,the immediate shear bond strength was measured by the universal mechanical testing machine,and the failure modes were observed.After 10000 cycles of thermocycling,the shear bond strength after aging was tested and the failure modes were observed.The influences of different sandblasting conditions on the bonding properties of this material were evaluated.Part 2:Effects of cold atmospheric plasma on surface properties of resin nanoceramicThe resin nanoceramic was processed into square specimens and randomly divided into five groups according to different surface treatments:control group,sandblasting group,hydrofluoric acid etching group,helium gas cold atmospheric plasma group,argon gas cold atmospheric plasma group.Scanning electron microscopy(SEM)was used to observe the surface microstructure and measure the surface roughness of each sample,and the influence of CAP on the physical properties of the material was analyzed.The surface water contact angle was detected and X-ray photoelectron spectroscopy was performed to analyze the influence of CAP on the chemical properties of the material.Part 3:Effects of different cold atmospheric plasma on the bonding properties of resin nanoceramicThe resin nanoceramic was processed into square specimens and randomly divided into nine groups according to different surface treatments:control group,sandblasting combined silane coupling agent group,hydrofluoric acid etching combined silane coupling agent group,helium gas cold atmospheric plasma group,helium gas cold atmospheric plasma combined silane coupling agent group,sandblasting combined helium gas cold atmospheric plasma and silane coupling agent group,argon gas cold atmospheric plasma group,argon gas cold atmospheric plasma combined silane coupling agent group,sandblasting combined argon gas cold atmospheric plasma and silane coupling agent group.After the resin was bonded to the surface of the specimens,the immediate shear bond strength was measured by the universal mechanical testing machine,and the failure modes were observed.After 10000 cycles of thermocycling,the shear bond strength after aging was tested and the failure modes were observed.Evaluate the influence of different CAP alone or in combination with other surface treatment methods on the bonding properties of this material.Results:Part 1:Effects of different sandblasting conditions on the bonding properties of resin nanoceramicAfter sandblasting,the surface roughness of RNC increases.Under different sandblasting conditions,the surface micromorphology of RNC is obviously different.The surface microcracks and structural damage of RNC can be caused by high sandblasting pressure(0.2MPa)and large sandblasting particles(110?m).Under different sandblasting conditions,the difference of surface water contact angle is not obvious,but they are obviously greater than the control group(P<0.05).The immediate shear bond strength and aging bond strength of RNC after sandblasting were significantly higher than those of control group and silane coupling agent group.There was no significant difference in immediate shear bond strength among different sandblasting conditions(P>0.05).After thermocycling,the shear bond strength of group(0.1MPa 50?m)was the highest,and there was no significant difference between the groups before and after thermocycling(P>0.05).Large sandblasting pressure(0.2MPa)and large sandblasting particles(110?m)increased the proportion of cohesive fracture in failure mode,and internal cracks appeared after fracture.Part 2:Effects of cold atmospheric plasma on surface properties of resin nanoceramicAfter sandblasting and hydrofluoric acid etching treatment,the surface microstructure changes and the surface roughness increases significantly.However,helium gas and argon gas cold atmospheric plasma treatment did not affect the surface microstructure of RNC,and the roughness was not significantly different from control group,and the surface water contact angle of the material was significantly reduced to 10.18°±1.36°and 7.58°±1.79°.Analysis of surface chemical elements showed that C element decreased,O element increased,C/O ratio decreased significantly,and hydroxyl group increased on the surface of the material after the two kinds of CAP treatment.Part 3:Effects of different cold atmospheric plasma on the bonding properties of resin nanoceramicThe immediate shear bond strengths of RNC in all treatment groups were significantly higher than control group(P<0.05).The three groups of argon gas plasma(argon gas plasma group 33.97±2.04 MPa,argon gas plasma+silane coupling agent group 33.78±1.60 MPa,sand blasting+argon gas plasma+silane coupling agent group 32.52±2.31 MPa)obtained the highest bonding strength.There was no significant difference between sandblasting+silane coupling agent group(31.50±2.74 MPa)and silane coupling agent group(P>0.05).The bonding strength of helium gas plasma alone(27.93±1.74 MPa)and combined with silane coupling agent(28.51±1.71 MPa)was slightly lower,but after sandblasting combined with helium gas plasma and silane coupling agent,the bonding strength was higher(32.10±2.57MPa).However,after sandblasting,the cohesive fractures of each group increase obviously.After thermocycling,the shear bond strengths of RNC in all treatment groups were significantly higher than control group except the hydrofluoric acid etching+silane coupling agent group(P<0.05).The bonding strength of argon gas plasma combined with silane coupling agent was the highest(32.38±1.42 MPa),and there was no significant difference in bonding strength before and after thermocycling(P>0.05).After thermocycling,the bonding strength of helium and argon gas plasma groups decreased the most(17.55%and 16.74%),and the bonding strength of helium and argon gas plasma+silane coupling agent groups decreased the least(8.88%and 4.15%).Conclusion:1.Sandblasting can increase the surface roughness of RNC,and the treatment combined with silane coupling agent can significantly improve the bonding strength of this material.The use of 0.1MPa 50?m Al2O3 sandblasting condition is the suitable sandblasting condition to improve the bonding strength.2.Helium gas and argon gas cold atmospheric plasma treatment do not change the surface morphology of RNC,but can significantly improve the surface wettability of this material,and introduce active chemical groups.Different CAP treatment can improve the bonding properties of RNC,which is a new surface treatment method for RNC bonding.The argon gas plasma combined with silane coupling agent shows the highest bonding strength. |
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