Effect Of Sealant On Microleakage Around The Edge Of Stainless-steel Brackets: An In Vitro Study

AIM To observe and compare the effect of different type of adhesive matejrial and different type of etching methods on the microleakage around bonded metal brackets, to analyze the effect of sealant on the microleakage around the metal brackets and to offer a method to prevent demineralization around bonded brackets in clinics.METHODS 72 healthy premolars extracted for orthodontic reason were selected in the study. Samples were divided into three groups, 24 in each. Group A: etched With 37% phosphate and bonded with JingJin adhesive; Group B: with 37% phosphate+3M Transbond ; Group C: self-etching primer + 3M Transbond . Each group was divided into two subgroups, experimental group (A2. B2. C2) and control group (A1 , B1 . C1) .Experimental group was treated with sealant around the metal brackets. All samples were thermalcycled about 500 times, then put into 1% methylenum solution for 24 hours. Microleakage of samples was observed under 25 X stereomicroscope, the interface of adhesive and tooth surface were observed under stereomicroscope and scanning electric microscope.RESULTS (1)Significant difference were found among group three groups (F=22.462, P<0.01), Multiple Comparison showed no significant difference between Group A1 and Group B1(P>0.05). Significant differences were found between group A1 and C1 (P<0.05), group B1 and C1 (P<0.05) respectively. (2) Significant differences between occlusal microleakage and gingival microleakage were found in group A1 (P>0.05) , group B1 (p<0.01) and group C1 (P<0.01) respectively. (3)Significant difference of microleakage was found between group A1 and A2 (P>0.01), B1 and B2(P<0.05) respectively, no difference was found between group C1 and C2(P>0.05). (4) Under SEM (Scanning Electric Microscope), close bonding was discovered on the enamel-adhesive interface when phosphate was used, but loose bonding was seen when self-etching primer was used.CONCLUSION (1) The type of adhesive has no effect on microleakage. (2)Different etching methods are relevant to microleakage, microleakage of self-etching primer groups is more than that of phosphate groups. (3) Sealant can reduce microleakage when phosphate is used, but has no effect when self-etching primer is used. (4)Gingival microleakage is significant larger than occlusal microleakage in each group. (5)Probablythere is correlation between microleakage and the shape of enamel-adhesive interface .