Influence of antioxidant and treating time on microleakage of filling resin after intracoronal bleaching
Objective To evaluate the effection of two different antioxidants and the treating time on the microleakage of filling resin after intracoronal bleaching.Methods One hundred and twenty extracted premolars were randomly divided into ten groups(n=12).Group A:unbleached group,Group B:bleached group,Group C:10％SA gel,Group D:10％SA gel with 0.2％Tween 80.According to the treatment time of the antioxidant(10 min,30 min,60 min,120 min),the ex-perimental group was further divided into four subgroups(Cl/C2/C3/C4,D1/D2/D3/D4).Then the cavity was fillled with composite resin.After thermal cycles,ten samples in each group were put into 2％methylene blue for 24 hours.And the microleakage of filled resin was observed at buccolingual under stereomicroscope.The micromorphology of the bonding interface in the remaining samples was observed with scanning electron microscope.Results The microleakage of group B were apparently higher than the group A(P＜0.001).There were apparent differences between C1、C2 and C3(P＜0.001),D2、D3 and D4,C2/C3/C4 and B(P＜0.05),D1/D2/D3/D4 and B,D4 and A(P=0.0145).The obvious gap between the filling resin and dental tissues was observed by SEM in group B,and the amount of gaps was the largerest in all groups.The gap decreased gradually and the the bonding interface was not well formed in group C.There was obvious gap in group D1.And as the treating time was extended,the filling resin was well integrated with dental tis-sue,the bonding interface was well formed in group D4.Conclusion When the treating time of 10％sodium ascorbate gel was 60 min,the microleakage of filling resin was the minimum after intracoronal bleaching.The microleakage of fill-ing resin decreased distinctly while applying 10％sodium ascorbate gel combined with a surfactan(Tween 80,0.2％)for 10min.As the treating time was extended,the amount of microleakage in group D was gradually decreased.Effectiveness of 10％sodium ascorbate hydrogel combined with a surfactan(Tween 80,0.2％)was obviously better than 10％sodium ascorbate hydrogel.
Sodium ascorbate gelIntracoronal bleaching with carbamide peroxideMicroleakage
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