[Comparison of nanoleakage in composite restorations following application of self-etch and total-etch adhesives in primary and permanent teeth]

Nanoleakage can cause discoloration around restoration margins, secondary caries, postoperative sensitivity and finally loss of restoration, thus adequate hybrid layer is of primary importance in prevention of nanoleakage in adhesive restorations. Because of structural differences between primary and permanent dentin, evaluation of nanoleakge in primary teeth is very important. The aim of this study was to evaluate the nanoleakage in composite restorations following application of self -etch and total-etch adhesives in primary and permanent teeth. In this experimental study, Cl V cavities were prepared in buccal surfaces of 20 extracted primary molars and 20 extracted premolars. Each group was divided into 2 subgroups: In group [A], Gluma One Bond and in group [B], iBond adhesive materials were applied. After silver nitrate staining, specimens were mesiodistally sectioned and polished and then SEM examination was carried out to measure the nanoleakage .Data were analyzed statistically using, ANOVA and Duncan tests with p<0.05 as the limit of significance. Factors tested had no significant effect on each other. Primary teeth showed more nanoleakage than permanent teeth [P<0.05]. Mean nanoleakage was significantly higher in cervical than occlusal margins [P<0.05] and also in iBond than in Gluma One Bond in primary teeth [P<0.05]. In permanent teeth, the lowest nanoleakage was observed in Gluma One Bond. The result of this study indicates that the use of total etch dentin adhesives [Gluma One Bond] in bonded restorations results in less nanoleakage in primary and permanent teeth

[ effect of different surface treatments of stainless steel crown and different bonding agents on shear bond strength of direct composite resin veneer]

Stainless steel crown [SSC] is the most durable and reliable restoration for primary teeth with extensive caries but its metalic appearance has always been a matter of concern. With advances in restorative materials and metal bonding processes, composite veneer has enhanced esthetics of these crowns in clinic. The aim of this study was to evaluate the shear bond strength of SSC to composite resin using different surface treatments and adhesives. In this experimental study, 90 stainless steel crowns were selected. They were mounted in molds and divided into 3 groups of 30 each [S, E and F]. In group S [sandblast], buccal surfaces were sandblasted for 5 seconds. In group E [etch] acidic gel was applied for 5 minutes and in group F [fissure bur] surface roughness was created by fissure diamond bur. Each group was divided into 3 subgroups [SB, AB, P] based on different adhesives: Single Bond, All Bond2 and Panavia F. Composite was then bonded to specimens. Cases were incubated in 100% humidity at 37°C for 24 hours. Shear bond strength was measured by Zwick machine with crosshead speed of 0.5 mm/min. Data were analyzed by ANOVA test with p<0.05 as the limit of significance. There was no statistical interaction between surface treatment and adhesive type [P>0.05] so the two variables were studied separately. No significant difference was observed in mean shear bond strength of composite among the three kinds of adhesives [P>0.05]. Similar results were obtained regarding surface treatments [P>0.05]. Based on the results of this study, treating the SSC surface with bur and using single bond adhesive and composite can be used successfully to obtain esthetic results in pediatric restorative treatments