The Effects Of Remineralization By Nanoscale Amorphous Calcium Phosphate Systems With Procyanidines On The Resin-dentin Bonding Strength And Durability

BackgroundThe wet-bonding technology can increase the immediate bonding strength of resin-dentin bonding,and improve the quality of tooth.As the mouth has an environment of constant temperature about 37℃,high humidity,rich in micro-organism and the occlusal load and temperature changing when eating the bonding strength of resin-dentin is affected by water residue in the hybrid layer,low adhesives penetration,the sensitivity of wet-bonding technology,hydrolysis of resin adhesives and the degradation of exposed collagen fibrils by endogenous dentin proteases.Nowadays,some research found that dentin biomimetic remineralization can protect the exposed collagen fibrils in the hybrid layer from being degraded by endogenous dentin proteases,but it often takes a long period of few months.Our previous research had established a nanoscale amorphous calcium phosphate system with procyanidines,which can reduce the remineralization time from a few months to short period of 1-2days.However the research of its effect on resin-dentin immediately bonding strength and bonding durability has not been performed.ObjectiveThis research is using a nanoscale amorphous calcium phosphate systems with procyanidines to remineralize the acid-etched dentin,using 10%NaClO to simulate aging effect,to analyze the surface morphology of demineralized layer and hybrid layer by scanning electron microscope,and to analyze the resin-dentin bonding strength by micro tensile bonding strength test,and finally draw a conclusion that whether this system can increase resin-dentin immediately bonding strength and bonding durability.MethodsThe remineralizing fluid was prepared based on our previous research.40 none-carious teeth and 32 slabs of teeth were prepared for standard bonding surfaces and randomly divided into 2 groups(20 teeth and 16 slabs in each group):the remineralization group was treated by the remineralizing fluid for 1 day after acid etching;the control group was untreated after acid etching.The slab samples of the two groups were treated with 10%NaClO for 0,1,2 and 3 hours(4 slabs in each sub-group)and then analyzed the surface morphology of demineralized layer and hybrid layer by scanning electron microscope.The teeth samples of the two groups were prepared into sticks(80 sticks in each group)and treated with 10%NaClO for 0 or 3 hours(40 sticks in each sub-group),and analyzed the resin-dentin bonding strength by micro tensile bonding strength test.The percentage of NaCIO degrading area was calculated under scanning electron microscope.Data statistical analysis was computed with SPSS Statistics 20.0.Result1.The scanning electron microscope result showed that the exposed collagen fibrils in the demineralized layer of control group were very thin while those of the remineralization group were wrapped by minerals.The micro tensile bonding strength test showed that the micro bond strength of remineralization group was significantly higher than that of the control group.2.The scanning electron microscope result showed that the exposed collagen fibrils in the demineralized layer of control group were degraded gradually by NaCIO after treated for 1,2 and 3 hours;the exposed collagen fibrils of the remineralization group were not be degraded by NaCIO because they were wrapped by minerals.3.The micro tensile bonding strength test showed that the micro bond strength of remineralization group was significantly higher than that of the control group,both before and after NaCIO treatment(P<0.05).The percentage of NaClO degrading area of remineralization group was significantly smaller than that of the control group(P<0.05).ConclusionThis nanoscale amorphous calcium phosphate system with procyanidines can remineralize the demineralized collagen fibrils only 1 day and increase resin-dentin bonding strength and bonding durability.