Previous researches have shown that dental anesthetic cartridges can be easily contaminated in dental clinics after opening sealed cartridges and being used. Also, previous researches have recommended that swapping of open anesthetic cartridges can minimize such contamination; however, there is no published data about the effect of different types of swaps on minimizing contamination of dental anesthetic cartridges. Objectives: The purpose of this study was to evaluate the effectiveness of two different techniques of swapping open dental anesthetic cartridges, their bacterial contamination, and to compare them to sterile, packed anesthetic cartridges. Methods: A hundred and thirty-five dental anesthetic cartridges were obtained from the following dental clinical areas: female students, male students, dental emergency, specialty and consultation and were divided into fifteen groups, each group with nine cartridges. The groups were further subdivided into three main categories, category one that were obtained directly from sterile packed anesthetic boxes, category two were all open cartridges and swapped with an alcohol swap and category three were all open cartridges and swapped with sterile gauze. All cartridges were embedded into a cysteine lactose electrolyte deficient agar (CLED agar) and cultured for gram positive and negative cocci and bacilli bacteria. The number of agar plates that showed any bacterial growth was counted for each category. Results: All alcohol-swapped and sterile packed cartridges were free from all types of bacteria. However, the sterile gauze-swapped cartridges showed spread of gram positive cocci of 85%; Gram positive bacilli 12%, and Gram negative bacilli 3% of the total bacterial growth over the surface of those cartridges. The overall bacterial growth however, was scanty and of no clinical significance. Conclusion: The results of this study suggest the use of an alcohol swap before using open anesthetic cartridge or using sealed ones for minimizing bacterial contamination in dental offices.