title: The effect of drying dental unit waterline biofilms on the bacterial load of dental unit water.
abstract: OBJECTIVE
  To evaluate drying of the dental unit waterlines (DUWL) as a new method of controlling the bacterial biofilm therein and thereby to reduce the number of living bacteria in dental unit water.
  
  
  METHODS
  18 dental units were incorporated into the study. Six units constituted the experimental units, which were emptied for stagnant water in the DUWL every night; six units were chlorinated every night (positive controls), and six units were left untreated (negative controls).
  
  
  METHODS
  Water samples from the ultrasonic scaler were examined microbiologically according to the guidelines from the Danish Standard Association and the number of colony forming units (cfu) per ml of water was determined.
  
  
  RESULTS
  Drying of DUWL did not reduce the number of cfu per ml in dental unit water below the levels found in DUWL left untreated.
  
  
  CONCLUSIONS
  The drying of the waterlines for about 16 hours per day during a 19-day period did not result in reduced counts of bacteria in water samples from the experimental units.
authors.affiliation: Department of Oral Microbiology, Institute of Odontology, Faculty of Health Sciences, University of Copenhagen, Denmark. nef@odont.ku.dk
authors.forename: N E
authors.initials: NE
authors.lastname: Fiehn
authors.forename: T
authors.initials: T
authors.lastname: Larsen
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D018441:Biofilms; D015169:Colony Count, Microbial; D003748:Dental Equipment / Q000382:microbiology*; D012534:Dental Scaling / Q000295:instrumentation; D004202:Disinfectants / Q000627:therapeutic use; D004203:Disinfection / Q000379:methods*; D006801:Humans; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D014464:Ultrasonic Therapy / Q000295:instrumentation; D014871:Water Microbiology
chemical_list: D004202:Disinfectants; D012973:Sodium Hypochlorite