Study Of Young Permanent Enamel And Adult Permanent Enamel Total-etching Bonding

PURPOSE:To determine the suitable enamel etching time for young permanent by studying of young permanent and adult permanent tooth enamel etching interface by SEM and resining bond strength by Micro-tensile test.METHODS:Young permanent and adult permanent tooth each34were selected.One sample was randomly selected from each group to study of young permanent and adult permanent tooth enamel-face by SEM. Three samples were randomly selected from each group and the buccal surface of each sample was divided into mesial,central and distal.Each part was observed by SEM after etched15s,30s or60s randomly. The remaining30samples were divided into15s group (etching15s),30s group (etching30s),60s group (etching60s).The samples were made into resin-enamel resining bond specimens to test the maximum load when the specimens breaking. All results were statistically analyzed with SPSS17.0software.RESULTS:Young permanent and adult permanent enamel surfaces are the presence of pores, cracks and other mineralization incomplete performance and young permanent enamel surface severe than in adults.The longer etching time, the enamel surface decalcification more serious; under the same etching time, young permanent teeth enamel demineralization serious than adults permanent. Young permanent group:The tensile strength at break of15s group,30s group,60s group were (13.692+2.526) MPa,(11.265±1.952) MPa,(11.057±2.237) MPa;the tensile strength at break of15s group was higher than the other two groups; the difference was statistically significant (P<0.05). Adult permanent group:The tensile strength at break of15s group,30s group,60s group were (11.128±2.418) MPa,(14.361±3.568) MPa,(11.224±2.370) MPa; the tensile strength at break of30s group was higher than the other two groups; the difference was statistically significant (P<0.05). CONCLUSIONS:The etching time of young permanent teeth should be appropriate to shorten,15S is the most appropriate etching time.