evaluation of diode laser (940 nm) irradiation effect on microleakage in class v composite restoration before and after adhesive application

Introduction: nowadays, the main focus of dental studies is on adhesive dental materials; since clinical long-term success of bonded restorations depended more on marginal microleakage minimization. so, the aim of this study was evaluation of diode laser irradiation effect on microleakage in class v composite restoration before and after adhesive application. materials and methods: in this in vitro-experimental study, standard class v cavity was prepared on lingual and buccal surfaces of 60 premolar teeth. for evaluation of microleakage, 60 teeth were divided randomly into four groups a, b, c, d (n=15): a) primer + adhesive (clearfil tm se bond), b) primer + diode laser + adhesive (940nm wave-length, 21j total energy, 0.7w power, 30s irradiation time) c) primer + adhesive + diode laser d) primer + diode laser + adhesive + diode laser. then, restoration was completed by z250 composite. for data analyzing, we used spss 16 software. for statistical analysis, we used non-parametric kruskal-wallis & mann-whitney tests at 0.05% significance level. results: according to non-parametric kruskal-wallis test, microleakage scores had not significant difference before and after laser irradiation on gingival margins (p=0.116). but, in occlusal margins the results were significant among the groups (p=0.015). also according to non-parametric mann-whitney tests among the occlusal microleakage scores, group b and d (diode laser irradiation after primer and diode laser irradiation after primer and adhesive) showed significant results. conclusion: this study findings showed that in 6th generation adhesives, diode laser irradiation on self-etch primer before bonding have significant effect on reduction of occlusal marginal microleakage in class v cavities although there was no significant positive effect of diode laser on gingival margins.