Nanoleakage Study On The Adhesive-dentin Interface Of Different Etching System

OBJECTIVES:Extracted premolars were chosen as the research subject for observation of nanoleakage in adhesive-dentin interface with different acid etching system by scanning electron microscopy (SEM). The marginal seal of adhesive agents were valued so as to find out the proper time of etching, and provide lab evidence for clinical application.METHODS:45 premolars extracted freshly was prepared with 320,400,600 -grit SiC paper under running water, and be randomly divided into 5 groups. Group E has 5 teeth coated by AP, and other groups which has 10 teeth each other coated by SB and PB separately after etched for 0,15,30,45 second. After stored in ammoniacal silver nitrate for 24h, and in developer for 8h, we made samples and observed them by scanning electron microscopy.RESULTS:1. SEM observation: Silver-staining particles can be seen in all groups but group A. Group B and E had the least silver-staining particles and the group D ( subgroup SB) had the most.2.NIH Image analysis: The nanoleakage of group A is zero. There was no significant difference in nanoleakage between SB and PB in group B (P>0.05) , but there was significant difference between SB and PB in group C and D (P<0.05 ) , namely subgroup SB generated more nanoleakage than subgroup PB in group C and D. Nanoleakage of SB and PB increased significantly with etching time (P<0.05) . There was no significant difference between group E and B (P>0.05) . AP in group E generated more less nanoleakage significantly than SB and PB in group C and D after be etched for 30 or 45 seconds (P<0.05) .CONCLUSIONS:1. Both total etching adhesive system and self-etching bond system can generate nanoleakage.2. The nanoleakage of dentin surface increases with etching time in total etching adhesive system, and SB is more effected by etching time than PB.3. There was no significant difference in nanoleakage between AP and SB or PB after etching for 15 seconds.