| Background:In clinical work,patients often come across the main complaints of abnormal tooth development,tooth wear and dislocation,etc.At present,the full crown restoration method is commonly used for restoration.However,this traditional restoration method will damage a large number of healthy dental tissues,which is not conducive to the long-term treatment effect of the affected teeth.In recent years,some scholars proposed oral minimally invasive aesthetic treatment(minimally invasive cosmetic dentistry MICD)concept,namely by minimally invasive or noninvasive treatment technology,to achieve the best aesthetic effect and repair effect.Ultra-thin overlays is a minimally invasive repair method that keeps the thickness of the prosthesis within 0.5-1mm.This repair method requires the material to have sufficient strength and toughness to resist the long-term occlusal cycle in the ultra-thin state,as well as sufficient wear resistance to avoid chewing wear.Traditional inlay repair materials include composite resins and ceramic materials.Resin materials have high toughness but low strength and poor wear resistance.Ceramic materials have better mechanical properties but are prone to fracture and breakage.In recent years,two kinds of CAD/CAM ceramic resin composite materials have been introduced by related materials researchers,both of which combine the advantages of high toughness of resin materials and high strength and high wear resistance of ceramic materials.However,their long-term stability in ultra-thin inlay applications is still rarely reported,so relevant studies are urgently needed to verify it.Objective:to study the fatigue and wear properties of CAD/CAM ceramic resin complex and glass ceramic in ultrathin overlaysMaterials and methods:1.40 isolated premolars were prepared into ultrathin overlays with a depth of 1mm.Vita Enamic(VE),Lava Ultimate(LU),IPS e.ax CAD(IC)and IPS Empress CAD(IE)were processed into overlays with corresponding thickness by CAD/CAM system and then bonded.Cyclic fatigue test was conducted,load strength,cycle times and failure mode were recorded,and the fatigue performance of four groups of specimens was compared by kaplan-meier survival analysis.2.The four materials and the enamel surface of the teeth in vitro were processed into5×5×10mm~3 specimens,and the abrasion experiment was conducted with talc porcelain,the friction coefficient curve was recorded,the volume loss was calculated and the surface abrasion morphology was observed under scanning electron microscopy,and the wear volume of five kinds of materials was compared on SPSS 22.0 using one-way anova.Results:the survival rates of LU,VE,IC and IE were 80%,50%,30%and 0%,respectively.The average fracture loads were 1360N,1280N,1200N and 820N.The fatigue properties of the four groups were significantly different(P<0.05).In terms of wear performance,the minimum wear amount of IC was[(7.84±1.45)mm~3],followed by LU[(11.28±1.96)mm~3],IE[(24.72±2.73)mm~3],VE[(34.64±2.63)mm~3],which were all smaller than enamel Y[(50.32±3.30)mm~3].There was a statistically significant difference in the wear volume between the four materials and the enamel group(P<0.05).Conclusion:The fatigue performance of ceramic resin composite is better than that of glass ceramic.In terms of wear performance,its wear resistance is not completely better than that of glass and ceramic,but it has less damage to the abrasive.The fatigue and abrasion properties of ceramic resin composites can meet the demand of ultra-thin overlay. |
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