ObjectiveTo explore the validity period of oral sterilizing instruments in different packages inside the bio-safety cabinet. MethodsInside the bio-safety cabinet, we brought the autoclaved dental gadgets packed in glassware and paper-plastic into microbial sampling cultivation experiment, and made observation of the bacteria growth at the 4th, 8th, 24th hour after sterilizing, with the sampling of once per 24 hours, lasting 10 days. Samples taken from the gadgets in paper-plastic each time when samples were taken from the gadgets in glassware were as the control. ResultsUnder the condition that the bio-safety cabinet was not contaminated, no colony grew in neither group in 144 hours; 168 hours later, the cultivation results indicated that colonies started to grow（P<0.05）. ConclusionUnder the condition that the bio-safety cabinet is pollution-free, the validity period of gadgets in glassware packaging for dental clinic practices is far longer than the 4-hour limit after the sterilized packages are opened, as is stipulated in the "Operating Specifications for Sterilization Technology on Dental Instruments of Medical Institutions".