title: Infection control in digital intraoral radiography: evaluation of microbiological contamination of photostimulable phosphor plates in barrier envelopes.
abstract: OBJECTIVE
  The detectors (both solid-state sensors and photostimulable phosphor [PSP] plates) used for digital intraoral radiography cannot be autoclaved, and barriers are typically used to prevent the spread of infection. The aim of this study was to determine the effectiveness of a barrier envelope system for PSP plates.
  
  
  METHODS
  Disinfected PSP plates were aseptically inserted into barrier envelopes and placed in a periapical location. One PSP plate was placed in each of 28 patients, and 12 plates in each of 2 volunteers (D.S.M., J.D.W.). After retrieval, each PSP plate was removed from its barrier envelope, immersed in trypticase soy broth and aliquots were plated on trypticase soy agar. Bacterial colonies were counted 2 days later.
  
  
  RESULTS
  Fifty-two PSP plates in barrier envelopes were evaluated for contamination. Quality assurance of the PSP plates before clinical placement revealed defects in the integrity of 4 barrier envelopes, caused by forceps-related damage or failure to achieve a uniform seal. These defects allowed substantial contamination. Contamination also occurred as a result of failure to extract the PSP plate from the barrier envelope cleanly. Of the 44 barriers with no obvious defects that were placed by either final-year dental students or a radiologist, only 3 allowed bacterial contamination of the PSP plate.
  
  
  CONCLUSIONS
  Detectors contained in barrier envelopes remain a potential source of contamination. PSP plates must be disinfected between removal from a contaminated barrier envelope and placement in a new barrier envelope. In addition, placement into the barrier envelope should ideally be carried out under aseptic conditions. Finally, the integrity of each sealed barrier envelope must be verified visually before release to the clinic.
authors.affiliation: University of British Columbia, Faculty of dentistry, Vancouver, British Columbia. dmacdon@interchange.ubc.ca
authors.forename: David S
authors.initials: DS
authors.lastname: MacDonald
authors.forename: J Douglas
authors.initials: JD
authors.lastname: Waterfield
mesh_terms: D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods; D004866:Equipment Contamination / Q000517:prevention & control*; D006801:Humans; D019552:Infection Control, Dental / Q000295:instrumentation*; D019252:Radiography, Dental, Digital / Q000295:instrumentation*; D014962:X-Ray Film / Q000382:microbiology*