Effect of repeated cycles of chemical disinfection on the roughness and hardness of hard reline acrylic resins.
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.
Pinto
Luciana de Rezende
Lde R
Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
Acosta
Emílio José T Rodríguez
EJ
Távora
Flora Freitas Fernandes
FF
da Silva
Paulo Maurício Batista
PM
Porto
Vinícius Carvalho
VC
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
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