title: Viability changes: microbiological analysis of dental casts.
abstract: BACKGROUND
  This study evaluated the survival of the most prevalent oral bacteria and fungi (Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, and Candida albicans) in dental casts, and compared changes in the amounts of these microorganisms at different time intervals to determine how long dental casts may pose threat to the health of dental personnel and patients.
  
  
  METHODS
  When manufacturing the casts, regular water was replaced with sterile distilled water, where suspensions of the studied bacteria or the fungus at certain concentrations were prepared. When the dental casts were fully set (solidified), plaster shavings were examined immediately after the contact of the studied microorganism with the plaster, as well as after 1, 2, 24, 48, 72, 96, and 120 hours. Following that, we measured how the amount of the studied bacteria and fungi in 1 gram of the plaster changed within the studied period of time.
  
  
  RESULTS
  Klebsiella pneumoniae survived in plaster for up to 4 days, and the reduction in the number of these bacteria became statistically significant after 1 day (p<0.05). Staphylococcus aureus remained viable in plaster for up to 4 days, and the number of these bacteria dropped after 1 day (p<0.05). Escherichia coli disappeared after 2 days, and a reduction was already observed after 2 hours (p<0.05). Candida albicans in plaster models died within 2 days, and a reduction in their number was observed after 1 day (p<0.05).
  
  
  CONCLUSIONS
  The microorganisms did not multiply in the gypsum casts and their number significantly dropped instead of increasing.
authors.affiliation: Faculty of Odontology, Clinic of Dental and Maxillary Orthopedics, Lithuanian University of Health Sciences, Medical Academy, Kaunas, Lithuania.
authors.forename: Juozas
authors.initials: J
authors.lastname: Žilinskas
authors.affiliation: Faculty of Odontology, Clinic of Dental and Maxillary Orthopedics, Lithuanian University of Health Sciences, Medical Academy, Kaunas, Lithuania.
authors.forename: Jonas
authors.initials: J
authors.lastname: Junevičius
authors.affiliation: Medical Academy, Faculty of Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Agnė
authors.initials: A
authors.lastname: Ramonaitė
authors.affiliation: Department of Microbiology, Lithuanian University of Health Sciences, Medical Academy, Faculty of Medicine, Kaunas, Lithuania.
authors.forename: Alvydas
authors.initials: A
authors.lastname: Pavilonis
authors.affiliation: Faculty of Odontology, Clinic of Dental and Maxillary Orthopedics, Lithuanian University of Health Sciences, Medical Academy, Kaunas, Lithuania.
authors.forename: Alvydas
authors.initials: A
authors.lastname: Gleiznys
authors.affiliation: Faculty of Odontology, Clinic of Dental and Maxillary Orthopedics, Lithuanian University of Health Sciences, Medical Academy, Kaunas, Lithuania.
authors.forename: Jurgina
authors.initials: J
authors.lastname: Sakalauskienė
mesh_terms: D001419:Bacteria / Q000254:growth & development*; D002176:Candida albicans / Q000254:growth & development; D015169:Colony Count, Microbial; D015921:Dental Implants / Q000382:microbiology*; D004926:Escherichia coli / Q000254:growth & development; D005658:Fungi / Q000254:growth & development*; D006801:Humans; D007711:Klebsiella pneumoniae / Q000502:physiology; D050296:Microbial Viability; D013211:Staphylococcus aureus / Q000502:physiology
chemical_list: D015921:Dental Implants