The Experimental Study On The Leakage Of Adhesive Interface With Different Dental Adhesive Systems

Objective:The purpose of this study was to evaluate the effects of different dentin adhesive systems on the microleakage and nanoleakage beneath the restoration.Method:80 intact young human premolars tooth extracted for orthodontic reason were used for this study.A cavity preparation was performed at 1mm above the Cemento-Enamel Junction(CEJ) on opposite sides of each teeth(mesial and distal).The tooth were randomly divided into 8 groups: C0,C1,NT0,NT1,XⅢ0,XⅢ1,XⅤ0 and XⅤ1.Group C0 and C1 were used as negative control groups,and their adhesive interfaces were performed without adhesive system.Group NT0 and NT1,group XⅢ0 and XⅢ1,group XⅤ0 and XⅤ1 were bonded with Prime Bond NT,XenoⅢand XenoⅤeach according to manufacturers'recommendations.Composite resin restoration(Ceram·X) was build up on all prepared cavities in a routine manner.And then group C0,NT0,XⅢ0 and XⅤ0 were immersed in distilled water at 37℃;group C1,NT1,XⅢ1,XⅤ1 were thermocycled for 5000 times.The apical foramen of each teeth was covered with self-curing rising followed by apex.Two layers of nail varnish were applied to all surfaces of the teeth leaving 1mm away from the cavity margins. All the tooth were immersed in 500g/L ammoniacal silver nitrate (pH=9.5) solution for 24 hours at 37℃,and were washed by distilled water for 10 seconds.After this,all samples were immersed in the developer solution for 8 hours and exposured by the fluorescent lamp at the same time.Subsequently,all the tooth were washed by distilled water for 20 seconds and were desiccated.Each specimen was sliced longitudinally with a low speed diamond disk with water coolant,producing approximately 2-mm wide samples then polished the samples.In the last, all the samples were evaluated under the Scanning electron microscopy (SEM) for the leakage of silver.Results:1.In the groups which were not thermocycled,there is the lest silver leakage beneath restoration in Prime Bond NT,much less than the leakage in the adhesive interface of XenoⅢand XenoⅤ(P＜0.05);But the extent of leakage was not so significantly different between XenoⅢand XenoⅤ(P＞0.05).2.In the groups which were thermocycled,the extent of leakage in the adhesive interfaces treated by Prime Bond NT,XenoⅢand XenoⅤis not so significantly different(P＞0.05).3.Between Group NT0 and NT1,Group XⅢ0 and XⅢ1,Group XⅤ0 and XⅤ1,the exent of leakage is not so significantly different(P＞0.05). Conclusion:1.Among the three dental adhesive systems(Primer Bond NT,XenoⅢand XenoⅤ),Primer Bond NT can decrease the leakage of the adhesive interface efficiently;which effccts is much better than XenoⅢand XenoⅤ.2.There is nanoleakage in all adhesive interfaces(Primer Bond NT, XenoⅢand XenoⅤ).3.It is efficient to observe and evaluate nanoleakage with SEM.