title: Effect of 0.2% chlorhexidine on microbial and fungal contamination of dental unit waterlines.
abstract: BACKGROUND
  It is known that dental unit waterline can be a source of infection. The aim of this study was to evaluate the efficacy of a mouthwash, chlorhexidine, in controlling microbial and fungal contamination of dental unit waterlines.
  
  
  METHODS
  In the present experimental study, the water in high-speed handpieces and air/water syringes of 35 dental units in a dental school was investigated microbiologically. Five of the units and one tap water served as controls; 100-200-mL water samples were collected aseptically in sterile containers in the morning after a 2-min purge. Water reservoir bottles were emptied and 50 mL of 0.2% chlorhexidine mouthwash was introduced into the tank. Then the water syringe was used to flush the waterline until the pink-colored chlorhexidine was observed to flow from the water syringe. Before the next day's session and before the students used the unit, two water samples from the water syringe and water turbine was collected. The samples were transferred to the laboratory. After 48 h at 37°C, the microbial colonies were counted. The number of these colonies was evaluated using colony forming unit CFU. Data were analyzed with Mann - Whitney U test and SPSS 13.5 statistical program. The statistical significance was defined at P ≤ 0.05.
  
  
  RESULTS
  All 35 units were contaminated before chlorhexidine use; no contamination was detected after adding chlorhexidine to the waterlines of the units. After week 1, 28 of the 30 treated dental unit waterlines (DUWLs) had values of CFU/mL less than 200.
  
  
  CONCLUSIONS
  The present study showed that the use of chlorhexidine could reduce microbial counts in dental unit waterlines.
authors.affiliation: Oral and Dental Diseases Research Center, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Raha Habib
authors.initials: RH
authors.lastname: Agahi
authors.affiliation: Oral and Dental Diseases Research Center, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Maryam Alsadat
authors.initials: MA
authors.lastname: Hashemipour
authors.affiliation: Department of Oral and Maxillofacial Pathology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Kalantari
authors.affiliation: Department of Mycology, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Ayatollah-Mosavi
authors.affiliation: Microbiologist, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Aghassi
authors.affiliation: Medical Student, Iran.
authors.forename: Amir Hossein Gandjalikhan
authors.initials: AH
authors.lastname: Nassab
keywords: Antibacterial; antifungal; chlorhexidine; dental; infection control
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