Effect of the Number of Adhesive Layers on Microleakage

Objectives: this work tested the null hypothesis that there was no influence of the different number of adhesive layers on microleakage in resin restorations. Methods: after remove the enamel by abrasive paper, class V (1.5 x 3 x 3 mm) cavities were made in bovine teeth. Resin restorations (Esthet X) were build-ups after the application of one-bottle adhesive systems, Prime & Bond 2.1 (PB), Prime & Bond NT (PBNT) and Single Bond (SB), altering the number of applications either 1 (1L) or 2 layers (2L). After the restorative procedures, each tooth was stored in 0.5% basic fuchsin aqueous solution for 4 hours and then rinsed and sliced in three slabs with 0.5 mm of thickness. The slabs were analyzed on stereoscope (100X) and the most infiltrate specimen was selected. The measurement of marginal leakage (mm) was made using the ImageTool program. Results: the results were submitted to Two-way ANOVA and post hoc Student-Newman-Keuls (£\=0.05). The data are in mean°"standard-deviation (n) to each adhesive system: SB1L 0.81„b0.35 (10); SB2L 0.73°"0.53 (10); PB1L 1.78°"0.76 (9); PB2L 1.36°"0.61 (10); PBNT1L 0.96°"0.25 (10); PBNT2L 1.49°"0.62 (9). The increase of adhesive layers for PBNT improved significantly the microleakage in the restorations (p<0.05). There was no statistically difference for both SB and PB when the number of adhesive layers were changed (p>0.05). Conclusions: the influence of the increment in the number of adhesive layers on microleakage was dependent on the material used.