title: Effect of repeated cycles of chemical disinfection on the roughness and hardness of hard reline acrylic resins.
abstract: OBJECTIVE
  The aim of this study was to assess the effect of repeated cycles of five chemical disinfectant solutions on the roughness and hardness of three hard chairside reliners.
  
  
  METHODS
  A total of 180 circular specimens (30 mm x 6 mm) were fabricated using three hard chairside reliners (Jet; n = 60, Kooliner; n = 60, Tokuyama Rebase II Fast; n = 60), which were immersed in deionised water (control), and five disinfectant solutions (1%, 2%, 5.25% sodium hypochlorite; 2% glutaraldehyde; 4% chlorhexidine gluconate). They were tested for Knoop hardness (KHN) and surface roughness (microm), before and after 30 simulated disinfecting cycles. Data was analysed by the factorial scheme (6 x 2), two-way analysis of variance (anova), followed by Tukey's test.
  
  
  RESULTS
  For Jet (from 18.74 to 13.86 KHN), Kooliner (from 14.09 to 8.72 KHN), Tokuyama (from 12.57 to 8.28 KHN) a significant decrease in hardness was observed irrespective of the solution used on all materials. For Jet (from 0.09 to 0.11 microm) there was a statistically significant increase in roughness. Kooliner (from 0.36 to 0.26 microm) presented a statistically significant decrease in roughness and Tokuyama (from 0.15 to 0.11 microm) presented no statistically significant difference after 30 days.
  
  
  CONCLUSIONS
  This study showed that all disinfectant solutions promoted a statistically significant decrease in hardness, whereas with roughness, the materials tested showed a statistically significant increase, except for Tokuyama. Although statistically significant values were registered, these results could not be considered clinically significant.
authors.affiliation: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Luciana de Rezende
authors.initials: Lde R
authors.lastname: Pinto
authors.forename: Emílio José T Rodríguez
authors.initials: EJ
authors.lastname: Acosta
authors.forename: Flora Freitas Fernandes
authors.initials: FF
authors.lastname: Távora
authors.forename: Paulo Maurício Batista
authors.initials: PM
authors.lastname: da Silva
authors.forename: Vinícius Carvalho
authors.initials: VC
authors.lastname: Porto
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003822:Denture Liners; D003823:Denture Rebasing; D004202:Disinfectants / Q000627:therapeutic use*; D004203:Disinfection / Q000379:methods*; D005976:Glutaral / Q000737:chemistry; D006244:Hardness; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D004202:Disinfectants; D008689:Methacrylates; D008768:Methylmethacrylates; C514244:tokuyama rebase fast II; D014867:Water; C103363:kooliner; C069716:Jet, dental resin; D012973:Sodium Hypochlorite; C010882:chlorhexidine gluconate; D002710:Chlorhexidine; D005976:Glutaral