Journal of North Khorasan Medical Sciences No 43, Volume 11, Issue 3 A Study on Microbial Quality of Water Supply in Dental Units at Bojnourd Dental School in 2017 Mitra Hashemi 1, , Seyedeh Nastaran Asadzadeh 2,*, , Reza Ghorbanpour 3 , Khashayar Sobhani 4 , Zahra Hekmat Ara 4 , Nima Firouzeh 5 1 MSc of Statistics, North Khorasan University of Medical Sciences, Bojnourd, Iran 2 PhD of Environmental Health Engineering, North Khorasan University of Medical Sciences, Bojnourd, Iran 3 MSc of Environmental Health Engineering, North Khorasan University of Medical Sciences, Bojnourd, Iran 4 BSc of Environmental Health Engineering, North Khorasan University of Medical Sciences, Bojnourd, Iran 5 Student Research Committee, Kerman University of Medical Sciences, kerman, Iran * Corresponding author: Seyedeh Nastaran Asadzadeh, PhD of Environmental Health Engineering, North Khorasan University of Medical Sciences, Bojnourd, Iran. E-mail: snasadzadeh3@gmail.com DOI: 10.21859/nkjmd-110313 How to Cite this Article: Hashemi M, Asadzadeh SN, Ghorbanpour R, Sobhani K, Hekmat Ara Z, Firouzeh N. A Study on Microbial Quality of Water Supply in Dental Units at Bojnourd Dental School in 2017. J North Khorasan Univ Med Sci. 2019; 11(3):94-98. DOI: 10.21859/nkjmd-110313 Received: 04 Dec 2018 Accepted: 01 Jun 2019 Abstract Introduction: Dental units are among the equipment that flows through the dental application, and due to the durability of water and the probability of forming the biofilm. They can have a high microbial load. It is important to investigate this pollution, which should be frequently investigated due to the incidence of dangerous infections in people with weakness of the defense system, pollution and dental units. The aim of this study is to investigate the amount of bacterial infection and pollutant of Water Supply in Dental units at Bojnourd dental school 2017. Methods: This study was conducted by descriptive _ analytical method on the water units in Bojnourd dental school.30 active units of the College of Dentistry were selected for the sampling. The samples were cultured on proprietary environments, and after 48 h at 37 ° C the number of microbial colonies was counted. And finally the obtained data were analyzed by SPSS 20. Results: The results showed that the average total bacterial count before flushing and after flushing was 711 and 293 cfu / ml, respectively, which had the highest level of contamination in water before flushing. Conclusions: The results of this study concluded that flushing was one of the best methods to reduce microbial contamination and Considering that dental units at Bojnourd dental school are polluted, dentists should pay more attention to prevent infection from infected patients and dental staff. Keywords: Unit Water Microbiology Number of Colonies per mL Bacterial Pollutant Research Article