title: Color change of composite resins subjected to accelerated artificial aging.
abstract: OBJECTIVE
  The aim of this study was to evaluate the influence of accelerated artificial aging (AAA) on the color change of composite resins used in dentistry.
  
  
  METHODS
  Three composite resins were evaluated: Two microhybrids and one hybrid of higher viscosity, with different amounts and sizes of filler particles, shades C2 and B2. A total of 54 specimens were obtained (18 for each composite resin), made of a Teflon matrix (15 mm in diameter and 2 mm in height). The color measurements were obtained with a Spectrophotometer, (PCB 6807 BYK Gardner) before and after AAA. Data were submitted to the Kolmogorov-Smirnov test (α >0.05), ANOVA and Tukey test (α <0.05). After statistical analysis, the color difference among composite resins with the same shades was analyzed.
  
  
  RESULTS
  All composite resins showed unacceptable color changes after AAA (ΔE > 3). Considering the variable ∆E, it was observed that the color tone C2 was already statistically different for the microhybrid composite resin prior to AAA (P < 0.05) and in shade B2 for hybrid of higher viscosity and microhybrid with barium glass fluoride aluminum and silica dioxide (P < 0.01). After this process, a statistically significant difference was observed only for shade B2 between microhybrid composite resins (P < 0.01) and for hybrid of higher viscosity and microhybrid with barium glass fluoride aluminum and silica dioxide (P < 0.05). Regarding the color difference within a same composite resin group, before aging the composite resin hybrid of higher viscosity B2 showed the highest color variation rate and microhybrid with zirconium/silica C2 showed the lowest.
  
  
  CONCLUSIONS
  All composite resins presented unacceptable color changes after 382 h of aging and different composite resins with same hue, presented different colors before being subjected to the aging process (B2 and C2) and after (B2). It was also observed color difference within a group of the same composite resin and same hue.
authors.forename: Denise Cremonezzi
authors.initials: DC
authors.lastname: Tornavoi
authors.forename: José Augusto Marcondes
authors.initials: JA
authors.lastname: Agnelli
authors.forename: Heitor
authors.initials: H
authors.lastname: Panzeri
authors.affiliation: Department of Dental Materials and Prosthodontics, Faculty of Dentistry of Ribeirão Preto, São Carlos, Brazil.
authors.forename: Andréa Cândido
authors.initials: AC
authors.lastname: Dos Reis
mesh_terms: D000704:Analysis of Variance; D003116:Color; D003124:Colorimetry; D003188:Composite Resins; D003764:Dental Materials
chemical_list: D003188:Composite Resins; D003764:Dental Materials