Effect of repeated immersion solution cycles on the color stability of denture tooth acrylic resins.
OBJECTIVE
Chemical solutions have been widely used for disinfection of dentures, but their effect on color stability of denture tooth acrylic resins after repeated procedures is still unclear. The aim of this in vitro study was to evaluate whether repeated cycles of chemical disinfectants affected the color stability of two denture tooth acrylic resins.


METHODS
Sixty disc-shaped specimens (40 mm x 3 mm) were fabricated from two different brands (Artiplus and Trilux) of denture tooth acrylic resin. The specimens from each brand (n=30) were randomly divided into 6 groups (n=5) and immersed in the following solutions: distilled water (control group) and 5 disinfecting solutions (1% sodium hypochlorite, 2% sodium hypochlorite, 5.25% sodium hypochlorite, 2% glutaraldehyde, and 4% chlorhexidine gluconate). Tooth color measurements were made by spectrophotometry. Before disinfection, the initial color of each tooth was recorded. Further color measurements were determined after subjecting the specimens to 7, 21, 30, 45, 60, and 90 immersion cycles in each tested solution. Color differences (ΔE*) were determined using the CIE L*a*b* color system. Data were analyzed using two-way repeated measures analysis of variance (ANOVA) followed by Tukey tests. The significance level was set at 5%.


RESULTS
There were statistically significant differences in ΔE* among the 5 disinfectants and water during the 90 cycles of immersion for both denture tooth acrylic resins. Distilled water promoted the greatest color change in both denture tooth acrylic resins, nevertheless none of tested disinfectants promoted ΔE* values higher than 1.0 on these acrylic materials during the 90 cycles of disinfection.


CONCLUSIONS
Repeated immersion cycles in disinfecting solutions alter ΔE* values, however these values do not compromise the color of the tested denture tooth acrylic resins because they are imperceptible to the human eye.
Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
Paulo Maurício Batista da
PM
Silva
Emílio José Tabaré Rodríguez
EJ
Acosta
Matheus
M
Jacobina
Luciana de Rezende
Lde R
Pinto
Vinícius Carvalho
VC
Porto
D000180:Acrylic Resins / Q000737:chemistry*; D000704:Analysis of Variance; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D003116:Color; D019551:Dental Disinfectants / Q000737:chemistry / Q000494:pharmacology*; D003824:Denture, Complete; D004202:Disinfectants / Q000737:chemistry; D005976:Glutaral / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007101:Immersion; D008422:Materials Testing / Q000379:methods; D017797:Prosthesis Coloring; D011897:Random Allocation; D012973:Sodium Hypochlorite / Q000737:chemistry / Q000494:pharmacology; D013053:Spectrophotometry; D013997:Time Factors
D000180:Acrylic Resins; D019551:Dental Disinfectants; D004202:Disinfectants; D012973:Sodium Hypochlorite; C010882:chlorhexidine gluconate; D002710:Chlorhexidine; D005976:Glutaral