Title: Assessment of antimicrobial effect of Methylene Blue and Silver nanoparticles irradiated by diode laser on induced caries model (An In vitro Study)
Aim: Assessment of the antibacterial competence of 650nm diode laser, Methylene Blue (MB) and Silver Nano-Particles (Ag NPs) on Streptococcus Mutans present in 180 biofilm-induced- caries models. Methods: One hundred and eighty (n=180) dentin discs were obtained. Each disc measured in 4x5x6 mm. Samples were pre-conditioned with sterile artificial saliva at 37 ?C for 2 hours. Specimens were equally divided into 6 groups. One group was untreated (control) and the other 5 groups were subjected to either MB, Ag NPs, Laser 650, the combination of MB and Laser 650 and the combination of MB, laser 650 and Ag NPs. Results: Comparison of the log10 mean Colony Forming Units milliliter (CFU/ml) values of each of the treated 5 groups and the control group was found statistically significant (P-value <0.05).The combination of MB, laser and Ag NPs recorded the highest (95.28%) reduction percentage of CFU/ml. MB alone represented the least efficient anti-bacterial effect with 74.09% reduction percentage of CFU/ml. The efficiency difference among the Ag NPs treated group, the Laser 650nm treated group and the combined MB/Laser 650nm treated group was found statistically insignificant .Conclusion: combination of MB, laser and Ag NPs were found that they present the most efficient antibacterial activity.