The teeth of the patients that meet inclusion criteria will be anesthetized, isolated with a rubber dam. Cavity opened using conventional high-speed rotary instruments. The central cariogenic biomass and the superficial parts of the necrotic dentine will be removed with round burs. Caries lesion will be completely removed in the enamel/dentin junction. The excavation procedure will be terminated as soon as the soft and wet dentine was removed and the remaining tissue was leathery but not hard on exploring. A dentinal sample will then be collected from the base of the cavity using sterile spoon excavator as a baseline for bacteriological assessment. Then, application of either intervention or control agent, another dentinal sample will be collected using a sterile excavator and transferred into sterile tubes and transferred to the laboratory for microbiological analysis.