microleakage comparison of three types of adhesive systems versus gic-based adhesive in class v composite restorations

background and aims: new dentin bonding agents and techniques have been developed to reduce microleakage and create higher bond strength. this in-vitro study compared the microleakage of three resin-based adhesives versus a gic-based adhesive on class v composite restorations.  materials and methods: class v cavities were prepared on the buccal surfaces of 72 sound premolars, randomly assigned to six groups (n=12) and treated as follows: without any treatment (negative control group); total-etch (optibond solo plus); two-step self-etch (optibond xtr); one-step self-etch (optibond all-in-one) and gic-based adhesive (fuji bond lc) with pre-cure and co-cure techniques. the treated cavities were filled with a micro-hybrid resin composite (point 4, kerr). following finishing and polishing procedures, the specimens were placed in 100% humidity, stored in distilled water, thermocycled and then immersed in a methylene blue, sectioned, evaluated for microleakage and scored on a 0 to 3 ordinal scale.  results: none of the adhesives tested were capable of completely eliminating marginal microleakage. there were statistically significant differences among the test groups at occlusal margins; but at cervical margins were not. the fuji bond lc with co-cure and control groups had significantly greater microleakage scores at the occlusal margins. at the cervical margins, the bonded restorations with optibond xtr and optibond all-in-one adhesives presented significantly lower microleakage scores. also, there were no significant differences between the resin adhesive groups both at occlusal and cervical margins. the microleakage scores at the cervical margins were markedly higher than the occlusal margins in the groups bonded with optibond solo plus and fuji bond lc with pre-cure. the differences between fuji bond lc adhesive with pre-cure and co-cure techniques were significant. conclusion: this study encourages application of the fuji bond lc adhesive with pre-cure technique instead of the resin adhesives for marginal seal in class v composite restorations.