Introduction & Objective: The clinical success of sealant therapy depends on its ability to pro-vide a marginal integrity resulting in micro leakage absence. The aim of this study was to evaluate the effect of enamel surface treatment using Er.Cr:YSSG and applying bandings with current clinical method on a fissure sealant microleakage.

 Material & Methods: In this experimental study 60 human premolar teeth were assigned to 3 groups according to the conditioning as follows: (1) 35% phosphoric acid gel etching (2) Er,Cr:YSSG laser + applying a self-etch adhesive and (3) Er,Cr:YSSG laser + applying margin bond. All fissures were sealed by Helioseal F according to the manufacturer's instruc-tions. The samples were thermocycled for 500 cycles (5 degrees -55 degrees C), and im-mersed in a 0.5% basic fuchsin solution for 24 h. After sectioning, microleakage was evalu-ated by stereomicroscope at 6x magnification. Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney U tests at a significance level of 0.05.

Results: No dye penetration was perceived in 20%, 15%, and 0% of cases in groups 1, 2, and 3 respectively all specimens were suffering from microleakage, in group 3. There was no statistically significant difference of microleakage scores between groups 1 and 2 (P=0.976). in group 1 were significantly lower than those of group 3 (P=0.016), and those of group 2 were lower than group 3 (P=0.009).

Conclusions: The findings of this study showed that enamel conditioning prior to the place-ment of sealant by Er,Cr:YSSG laser combined with an self-etch adhesive prevent micro-leakage as effective as conventional acid etching.