Study On The Effect Of D-ribose Pretreatment On The Bonding Strength Of Dentin

Objective:In the process of dentin bonding,dentin is demineralized after acid etching,and exogenous collagenase and activated endogenous protease will produce enzymatic hydrolysis of collagen dentin,damaging the integrity of collagen dentin structure,which is very important for the stability and durability of dentin bonding.The crosslinking can protect the dentin collagen and improve the mechanical properties and resistance to enzymatic hydrolysis after dentin demineralization.In this study,D-ribose was selected as a new cross-linking agent to treat demineralized dentin,and the degradation of D-ribose on collagen fibers of dentin and the influence of D-ribose on the bonding strength of dentin after pretreatment were studied,so as to explore the feasibility of D-ribose pretreatment to improve the bonding strength of dentin.Methods:1.Eighty-eight carial-free intact third molars extracted from 18-25 years old patients were collected,and 40 of them were cut into dentin samples of2mm×2mm×6mm with enamel removed from the crown.10% phosphoric acid solution was completely demeralized,distilled water was used as blank group,and10% glutaraldehyde solution was used as control group.1wt% and 2wt% D-ribose aqueous solutions were prepared as the experimental group.The resistance of cross-linked demineralized dentin to exogenous collagenase was evaluated by the determination of dry mass loss ratio and hydroxyproline release.2.Eight isolated teeth were made into demineralized dentin samples as above and randomly divided into four groups(n=5): A.Before enzymolysis group B.After enzymolysis group C.1wt% D-ribose group D.2wt% D-ribose group,Group A and Group B were put into distilled water,Group C and Group D were put into 1wt%D-ribose and 2wt% D-ribose aqueous solution for 5 minutes,respectively.After thoroughly rinsed with distilled water,Group A was put into PBS solution for 48 hours.Group B,C and D were placed into Ⅰ type collagenase solution for enzymatic hydrolysis for 48 hours,and the changes of dentin surface in the four groups were observed and analyzed under scanning electron microscope.3.The remaining 40 teeth with enamel removed from the crown were randomly divided into four groups for total acid etching bonding according to different pretreatments before bonding(n=5):(1)Distillated water(2)10% glutaraldehyde(3)1wt% D-ribose(4)2wt% D-ribose.Each group was further divided into two groups A and B.Group A was stored in A 37℃ incubator for 24 h and then cut into microtensile samples of 1mm×1mm×8mm size for microtensile bonding strength test.Group B was aged for 5000 times after cold and hot cycling.The microtensile samples of the same size as group A were cut to test the microtensile bonding strength.Results:1.The dry mass loss ratio and hydroxy-proline release amount of 1wt% and2wt% D-ribose treatment groups were statistically significant compared with the blank group(P < 0.05),but not statistically significant compared with the control group(P > 0.05),which proved that the use of two concentrations of D-ribose treatment can reduce the mass loss of deminalized dentin.It effectively resisted the degradation of collagen of dentin by exogenous Ⅰ type collagenase.2.Scanning electron microscopy showed that there were significant differences in the surface morphology of dentin before and after treatment with exogenous Ⅰcollagenase.The structure of dentin surface and the edge of tubules were intact in the group before enzymolysis,and the collagen fibers in the wall of tubules remained stable.After treatment with Ⅰ type collagenase,the dentin was demineralized after acid etching,and the space between the collagen fibers of the dentin was widened.After enzymatic hydrolysis,the collagen fibers of the dentin in some areas were broken and showed a pit shape.However,after 1wt% and 2wt% D-ribose treatment,the connections between the collagen fibers of the Ⅰ collagenase hydrolysated group were close,and the basic structure of the collagen fibers of the dentin was still similar to that of the pre-hydrolysated group.3.In the microtensile bonding strength test,the microtensile bonding strength of1wt% and 2wt% D-ribose immediate group and aging group was increased compared with the corresponding blank group,with statistical significance(P < 0.05),but there was no statistical significance compared with 10% glutaraldehyde group(P > 0.05).In the aging group,the microtensile bonding strength of the blank group was significantly decreased compared with that of the immediate group(P < 0.05),and there was no statistical significance in the microtensile bonding strength of the 10%glutaraldehyde group,1wt% and 2wt% D-ribose groups before and after aging(P >0.05).Conclusion:1.The treatment of demineralized dentin with 1wt% D-ribose can improve the resistance of collagen to exogenous collagenase enzymatic hydrolysis,and play a role in maintaining the structural integrity of collagen dentin.2.After pretreatment with 1wt% D-ribose as a crosslinking agent,the bonding strength of resin-dentine was improved after immediate and cold/hot aging,indicating that D-ribose has the potential to improve the bonding strength of resin-dentine immediately and after aging.