title: Effect of three methods for cleaning dentures on biofilms formed in vitro on acrylic resin.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of three denture hygiene methods against different microbial biofilms formed on acrylic resin specimens.
  
  
  METHODS
  The set (sterile stainless steel basket and specimens) was contaminated (37 degrees C for 48 hours) by a microbial inoculum with 10(6) colony-forming units (CFU)/ml (standard strains: Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Candida albicans, Pseudomonas aeruginosa, and Enterococcus faecalis; field strains: S. mutans, C. albicans, C. glabrata, and C. tropicalis). After inoculation, specimens were cleansed by the following methods: (1) chemical: immersion in an alkaline peroxide solution (Bonyplus tablets) for 5 minutes; (2) mechanical: brushing with a dentifrice for removable prostheses (Dentu Creme) for 20 seconds; and (3) a combination of chemical and mechanical methods. Specimens were applied onto a Petri plate with appropriate culture medium for 10 minutes. Afterward, the specimens were removed and the plates incubated at 37 degrees C for 48 hours.
  
  
  RESULTS
  Chemical, mechanical, and combination methods showed no significant difference in the reduction of CFU for S. aureus, S. mutans (ATCC and field strain), and P. aeruginosa. Mechanical and combination methods were similar and more effective than the chemical method for E. faecalis, C. albicans (ATCC and field strain), and C. glabrata. The combination method was better than the chemical method for E. coli and C. tropicalis, and the mechanical method showed intermediate results.
  
  
  CONCLUSIONS
  The three denture hygiene methods showed different effects depending on the type of microbial biofilms formed on acrylic base resin specimens.
authors.affiliation: Department of Dental Materials and Prosthodontics, Ribeirão Preto Dental School, University of São Paulo, Brazil.
authors.forename: Helena F Oliveira
authors.initials: HF
authors.lastname: Paranhos
authors.forename: Cláudia H
authors.initials: CH
authors.lastname: Silva-Lovato
authors.forename: Raphael F
authors.initials: RF
authors.lastname: de Souza
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Cruz
authors.forename: Karina M
authors.initials: KM
authors.lastname: de Freitas-Pontes
authors.forename: Evandro
authors.initials: E
authors.lastname: Watanabe
authors.forename: Izabel Y
authors.initials: IY
authors.lastname: Ito
mesh_terms: D000180:Acrylic Resins; D018441:Biofilms / Q000187:drug effects*; D015169:Colony Count, Microbial; D003819:Denture Bases / Q000382:microbiology; D003820:Denture Cleansers; D003824:Denture, Complete / Q000382:microbiology*; D004203:Disinfection / Q000379:methods; D009910:Oral Hygiene / Q000379:methods*; D018709:Statistics, Nonparametric; D014099:Toothbrushing / Q000379:methods*
chemical_list: D000180:Acrylic Resins; D003820:Denture Cleansers