Comparative Evaluation Of Four Self-etching Adhesives On Dentin Of Primary Teeth In Vitro

Objective: Primary teeth are not only a major organ of mastication tochildren, but also play an important role in growthing and forming permanentteeth. Disease of primary teeth can reduce the masticatory function, decreasenutrition intake, influence the growth of dento-gnathicsystem phonetics, andaesthetics. Therefore, it heavily impacts on the physical and mentaldevelopment of children. Filling therapy is great value in the treatment ofprimary teeth. Proper dentin bonding material is the key point of improvingchildren's depends on adhesive systems. Good dentin adhesive system canmake enduring and effective bond strength,and also repair and seal themarginal defect of a cavity, therefore, to prevent postoperative sensitivity andmicro-leakage. During the past twenty years, significant improvements havebeen made in the field of dentin adhesives systems. From Totle-etchingadhesive system to Self-adhesive system, from Three-bottle to One-bottlesystem, and from Three-step to Single-step system. The sixth and seventhgeneration of dentin adhesive system commonly used in clinics mix withetchant, primer and adhesives together supplied as a single system. Theseadhesives are marketed as eliminating omitting acid etching, washing, anddrying procedures, thus greatly shortening the operation time,and solve theproblem with children of weak poor cooperation, rich saliva and intolerance oflong, redious etching steps. The sixth generation consists two-componentswhich can be mixed and reacted with each other before used prior toapplication. The seventh-generation actually embodies the true sense ofone-bottle system. Recent research showed that the bond strength of fourself-etching adhesives are as less technique sensitive, less time consuming,while the bonding strength is as effective as older adhesives. Nevetheless, thecomparison of sixth and seventh-generation self-etching adhesives on dentin of primary teeth has not been reported yet. In this study,the experiment wasundertaken at non-carious primary molars in vitro by applying micro-tensilestrength to detect the bond strength of the bonding interface on primary dentinbetween the sixth generation of adhesives(XenoIII, of Clearfil SE Bond) andseventh generation adhesives (XenoⅤ of Clearfil the S~3Bond) combinedwith the Spectrum TPH3composite resin, from which provides theexperimental basis for clinical application and experimental study.Method: Sixty freshly extracted sound human primary teeth were used inthe study. The enamel of the samples has been ground along the axis of teethat the buccal, lingual, mesial and distal directions, as well as the coronalenamel at the direction of perpendicular to the long axis of teeth to prepare flatdentin surfaces, followed by180#,400#,600#silicon carbide sandpaper,distilled water rinse. The prepared primary molars were randomly divided intofour groups. In group A, fifteen primary teeth were bonded using sixthgeneration bonding agent (XenoⅢ Bond). In group B, fifteen primary teethwere bonded using seventh generation bonding agent (XenoⅤ Bond). Ingroup C, fifteen primary teeth were bonded using sixth generation bondingagent (Clearfil SE Bond). In group D, fifteen primary teeth were bonded usingseventh generation bonding agent (Clearfil S~3Bond). A Teflon mold was usedto build the composite (Spectrum TPH3) cylinders on the dentinal surface ofall the specimens. The specimens were stored in distilled water at37oC for24hours. Each group was cut for3*3mm2cross sectional area along the longaxis of teeth. Then the specimens which the finest point is1mm at bondingsurface was trimmed into a shape of hourglass. Micro-tensile strength wastested for all the specimens with an Universal Testing Machine.Data were statistically analyzed using one-way ANOVA for multiplegroup comparisons by SPSS13.0sofeware.Results:The values of micro tensile strength of four self-etching adhesives ondentin of primary teeth were multiply compared: There was no significantdifference among XenoⅢ Bond, XenoⅤBond, Clearfil SE Bond and Clearfil S~3Bond (XenoⅢ Bond vs XenoⅤBond：P＞0.05; XenoⅢ Bond vs ClearfilS~3Bond：P＞0.05; XenoⅢ Bond vs Clearfil SE Bond：P＞0.05; XenoⅤBondvs Clearfil S~3Bond：P＞0.05; XenoⅤBond vs Clearfil SE Bond：P＞0.05;Clearfil S~3Bond vs Clearfil SE Bond：P＞0.05).Conclusion:1There was no any statistically significant difference among XenoⅢBond, XenoⅤBond, Clearfil SE Bond and Clearfil S~3Bond. The fourself-etching adhesives on dentin of primary teeth could achieve good bondstrength.2There was no significant difference between the sixth and seventhgeneration of dentin adhesives. But this study revealed that the overall meanof XenoⅤ Bond and Clearfil S~3Bond was slightly higher than XenoⅢ Bondand Clearfil SE Bond, due to less procedure time, more operator-friendly,therefore, it is more suitable for pediatric dentistry.