title: Antimicrobial and mechanical properties of acrylic resins with incorporated silver-zinc zeolite - part I.
abstract: The purpose of this in vitro study was to evaluate the antimicrobial activity of acrylic resins containing different percentages of silver and zinc zeolite, and to assess whether the addition of zeolite alters the flexural and impact strength of the resins.
  
  
  
  The characteristics of acrylic resins support microorganism development that can threaten the health of the dentures user.
  
  
  
  A microwave-polymerised (Onda-Cryl) and two heat-polymerised (QC20 and Lucitone 550) acrylic resins were used. The materials were handled according to the manufacturers' instructions. Fifty rectangular-shaped specimens (8 x 10 x 4mm) were fabricated from each resin and assigned to 5 groups (n = 10) according to their percentage of Irgaguard B5000 silver-zinc zeolite (0%- control, 2.5%, 5.0%, 7.5% and 10%). Flexural strength and Izod impact strength were evaluated. The antimicrobial activity against two strains of Candida albicans and two strains of Streptococcus mutans was assessed by agar diffusion method. Data were analysed statistically by one-way anova and Tukey's test at 5% significance level.
  
  
  
  The addition of 2.5% of Irgaguard B5000 to the materials resulted in antimicrobial activity against all strains. Flexural strength decreased significantly with the addition of 2.5% (QC20 and Lucitone 550) and 5.0% (Onda-Cryl) of Irgaguard B5000. The impact strength decreased significantly with the addition of 2.5% (Lucitone 550) and 5.0% (QC20 and Onda-Cryl) of zeolite.
  
  
  
  The addition of silver-zinc zeolite to acrylic resins yields antimicrobial activity, but may affect negatively the mechanical properties, depending on the percentage of zeolite.
authors.affiliation: Dentistry College, University of Franca, Franca, SP, Brazil. lucianacasemiro@hotmail.com
authors.forename: Luciana Assirati
authors.initials: LA
authors.lastname: Casemiro
authors.forename: Carlos Henrique Gomes
authors.initials: CHG
authors.lastname: Martins
authors.forename: Fernanda de Carvalho Panzeri
authors.initials: Fde C
authors.lastname: Pires-de-Souza
authors.forename: Heitor
authors.initials: H
authors.lastname: Panzeri
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000704:Analysis of Variance; D000891:Anti-Infective Agents, Local / Q000737:chemistry / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects; D003799:Dental Stress Analysis; D003819:Denture Bases; D004548:Elasticity; D008422:Materials Testing; D018583:Pliability; D012834:Silver; D013295:Streptococcus mutans / Q000187:drug effects; D017641:Zeolites / Q000737:chemistry / Q000494:pharmacology*; D015032:Zinc
chemical_list: D000180:Acrylic Resins; D000891:Anti-Infective Agents, Local; D017641:Zeolites; D012834:Silver; D015032:Zinc