Influence of double application technique on the bonding effectiveness of self-etch adhesive systems

To evaluate and compare the effect of double-application of single-step self-etch adhesives using microleakage study and to analyze the dentin-adhesive interfacial micromorphology.

In total, 72 extracted human premolars were divided into three groups for different self-etch adhesives (G Bond, GC [GB], Optibond, Kerr [OB], and Xeno V Plus, Dentsply [XV]). Class V cavities were prepared. Each group was further divided into two subgroups (n = 10) according to the placement technique of the adhesive, using the single-application [subgroup (a)] or double-application method [subgroup (b)]. Resin composite (Z 250, 3M ESPE, St. Paul, MN) was used to restore the cavities and light cured for 40 s. Twenty samples from each group were subjected to microleakage study. Two samples from both the subgroups of the three adhesives were used for scanning electron microscopic examination of the resin-dentin interfacial ultrastructure. Dye leakage scores were subjected to statistical analysis using Kruskal-Wallis and Mann-Whitney U-tests at significance level of P < 0.05.

GB depicted significantly more microleakage which was significantly greater than OB and XV. The double application led to significant decrease in microleakage of GB with no significant effect on the microleakage scores of other two all-in-one adhesives, that is OB and XV.

Double application of all-in-one self-etch adhesives improves the marginal sealing ability in dentin although it appears to be product dependent.