A dental syringe is widely used in most of dental treatment for giving local anesthesia to patients such as in root canal treatment and in common tooth extraction. It consists of a head, a tip, cartridge and a releasable coupling. It is widely used in dentistry and included in critical instruments as it penetrates in tissues and get contaminated with blood and saliva. The transmission of pathogens from one patient to another via contaminated devices has been high profile issue in infection control so it is necessary to sterilize it properly. The Cobalt-60 as gamma radiation source is used for complete sterilization of dental syringe. Different doses of gamma radiations selected according to the colonies appeared on the sample. The purpose of this study is to estimate an optimum dose of gamma radiation for appropriate sterilization of dental syringe and to evaluate the bioburden level on instrument before and after gamma radiation treatment Cobalt-60. Optimum dose for the private hospital is 25kGy as it provides complete sterility assurance at this dose. But for the private clinic and public hospital, 30kGy and 40kGy respectively is optimized for proper sterilization.