Research On The Bond Strength Of The Tooth-colored Restorations On The Enamel And Dentinal Of Primary Teeth

Experiment 1:The measurements on the shear bond strength of composite resin and two types of adhesive agents to the primary teethObjective The purpose of this study was to evaluate the shear bond strength between total-etching and self-etching adhesive system on the enamel and dentinal of primary teeth.Materials and Methods Forty retained deciduous teeth were randomly divided into 2 groups(A group and B group) and were respectively prepared into enamel and dentinal specimens. The two groups were respectively separated into 2 groups:total-etching and self- etching adhesive agent group. The four groups'shear bond strength were examined after being bonded using composite resin and the bonding interface rupture mode(pattern) were observed under stereomicroscope. Eight retained deciduous teeth were randomly divided into 2 groups (total- etching group and self- etching group) and were respectively prepared into enamel and dentinal specimens(2 specimens in each group),the bonding interface were observed using scanning electron microscope.Results In total- etching adhesive group,the shear bond strength of enamel specimen was significantly higher than that of dentinal specimen (P<0.05),in self- etching adhesive group, there was no statistical significance between the enamel and dentinal shear bond strength(P>0.05);The shear bond strength in total- etching adhesive group was significantly higher than that in self- etching adhesive group(P>0.05).Under stereomicroscope,75% of the bonding interface rupture mode(pattern) was mixed destruction between total- etching adhesive agent and primary teeth; 65% of the bonding interface rupture pattern was adhesive destruction around the primary teeth surface between self- etching adhesive agent and primary teeth. Under scanning electron microscope, there were lots of resin tags in bonding interface between total- etching adhesive agent and enamel; the mixed layer between the total- etching adhesive agent and dentin was thicker and the resin tag was longer and more; there were some interface gaps between the self- etching adhesive agent and enamel; there were not obvious resin tags, the mixed layer between the self- etching adhesive agent and dentin was thinner and the resin tag was shorter and less.Conclusion The shear bond strength of total- etching adhesive agent was significantly higher than that of self- etching adhesive agent on the enamel and dentinal of primary teeth.Experiment 2:Evaluationof the adhesive strength between four tooth-colored restorations and the enamel and dentinal of primary teethObjective To compare the shear bond strength between four tooth-colored restorations and primary teeth in order to offer a refrence to clinic application of the restorative materials.Materials and Methods Eighty retained deciduous molars were randomly divided into eight groups and were respectively prepared into standard bonding specimens using composite resin, polyacid-modified composite resins, glass ionomer cement and resin-modified glass ionomer cement.The shear bond strength of the eight groups was examined and the bonding interface rupture mode was observed under stereomicroscope.Results The shear bond strength of the four tooth-colored restorations in enamel group was significantly higher than that in dentinal group; there was no statistical significance of the shear bond strength between composite resin group and polyacid-modified composite resins group(P>0.5);there were significantly statistical difference between the other two groups(P<0.001).Under stereomicroscope, most of the bonding interface rupture mode was mixed destruction between the composite resin group and polyacid-modified composite resins group and primary teeth; the bonding interface rupture mode was interface destruction between glass ionomer cement and primary teeth; and most of the bonding interface rupture mode was adhesive destruction around the primary teeth surface between Rresin-modified glass ionomer cement.Conclusion The shear bond strength of the four tooth-colored restorations in enamel group was significantly higher than that in dentinal group; there was no statistical significance of the shear bond strength between composite resin group and polyacid-modified composite resins group using the same kind of total- etching adhesive agent; the shear bond strength of the glass ionomer cement group and resin-modified glass ionomer cement group was lower than that of the other groups and the glass ionomer cement group was the lowest.