摘要： Aim To assess the efficacy of phototherapy on bond strength and microleakage of bulk fill composites in comparison to conventional dentin surface treatments. Materials and Methods Ninety human third molars were divided into 3 groups (n=30 each) according to surface conditioning treatment. Group 1 (Etch and Bond) EB, group 2 was treated with Er,Cr: YSGG (ECL) and group 3 was treated with a diode laser (DL). Based on the type of bulk fill resin composite, samples were divided into six sub-groups. In sub-group 1, 2 and 3 (n=15) build-up was done using ZirconCore (ZC) and these subgroups were named as EB-ZC, ECL-ZC and DL-ZC. In subgroup 4,5,6 (n=15) MulticCore Flow (MC) was used for core build-up and these subgroups were named as EB-MC, ECL-MC, DL-MC. For shear bond strength (SBS) all the samples were exposed to loads using a universal testing machine. Five samples each from all subgroups were immersed in methylene blue dye for 24hours prior to microleakage testing. Data were assessed using analysis of variance and Tukey multiple comparisons test. Results: Among all the groups the lowest bond strength was achieved in DL-ZC [10.45(0.459)]. Similarly, the highest bond strength was attained in EB-MC[17.84(0.925)]. The highest microleakage scores amongst different group was exhibited in DL-ZC [82.45(39.459)] whereas, the lowest microleakage scores were displayed in EB-MC [31.21(15.92)]. Conclusion: Phototherapy in the form of Er,Cr:YSGG laser showed comparable adhesive bond outcomes to conventional etch and bond dentin conditioning techniques. Moreover, Multicore bulk fill material showed better bond strength and microleakage scores than zirconium particle infiltrated bulk fill composite in the presence of dentin phototherapy.