title: Effectiveness of six different disinfectants on removing five microbial species and effects on the topographic characteristics of acrylic resin.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effectiveness of disinfectant solutions (1% sodium hypochlorite, 2% chlorhexidine digluconate, 2% glutaraldehyde, 100% vinegar, tabs of sodium perborate-based denture cleanser, and 3.8% sodium perborate) in the disinfection of acrylic resin specimens (n = 10/group) contaminated in vitro by Candida albicans, Streptococcus mutans, S. aureus, Escherichia coli, or Bacillus subtilis as measured by residual colony-forming unit (CFU). In a separate experiment, acrylic resin was treated with disinfectants to monitor potential effects on surface roughness, Ra (microm), which might facilitate microbial adherence.
  
  
  METHODS
  Three hundred fifty acrylic resin specimens contaminated in vitro with 1 x 10(6) cells/ml suspensions of standard strains of the cited microorganisms were immersed in the disinfectants for 10 minutes; the control group was not submitted to any disinfection process. Final counts of microorganisms per ml were performed by plating method for the evaluation of microbial level reduction. Results were compared statistically by ANOVA and Tukey's test (p< or = 0.05). In a parallel study aiming to evaluate the effect of the tested disinfectant on resin surface, 60 specimens were analyzed in a digital rugosimeter before and after ten cycles of 10-minute immersion in the disinfectants. Measurements of superficial roughness, Ra (mum), were compared statistically by paired t-test (p< or = 0.05).
  
  
  RESULTS
  The results showed that 1% sodium hypochlorite, 2% glutaraldehyde, and 2% chlorhexidine digluconate were most effective against the analyzed microorganisms, followed by 100% vinegar, 3.8% sodium perborate, and tabs of sodium perborate-based denture cleanser. Superficial roughness of the specimens was higher after disinfection cycles with 3.8% sodium perborate (p= 0.03) and lower after the cycles with 2% chlorhexidine digluconate (p= 0.04).
  
  
  CONCLUSIONS
  Within the limits of this experiment, it could be concluded that 1% sodium hypochlorite, 2% glutaraldehyde, 2% chlorhexidine, 100% vinegar, and 3.8% sodium perborate are valid alternatives for the disinfection of acrylic resin.
authors.affiliation: Department of Oral Biosciences and Diagnosis, São José dos Campos Dental School, São Paulo State University (UNESP), São Paulo, Brazil.
authors.forename: Francine Cristina
authors.initials: FC
authors.lastname: da Silva
authors.forename: Estevão Tomomitsu
authors.initials: ET
authors.lastname: Kimpara
authors.forename: Maria Nadir Gasparotto
authors.initials: MN
authors.lastname: Mancini
authors.forename: Ivan
authors.initials: I
authors.lastname: Balducci
authors.forename: Antonio Olavo Cardoso
authors.initials: AO
authors.lastname: Jorge
authors.forename: Cristiane Yumi
authors.initials: CY
authors.lastname: Koga-Ito