title: Color stability of esthetic ion-releasing restorative materials subjected to pH variations.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the color stability of 3 types of fluoride-releasing restorative esthetic materials when exposed to pH variations: (1) a polyacid-modified resin composite; (2) a resin-modified glass ionomer cement; and (3) a conventional glass ionomer cement in 2 different storage conditions.
  
  
  METHODS
  Five samples of each material were stored in artificial saliva (pH 6.8) for 28 days. Five other samples were submitted for a pH-cycling during the same 28 days, which were immersed daily in a demineralizing solution (pH 4.5) for 7.5 hours and in a remineralizing solution (pH 7.0) for 16 hours. Color parameters were analyzed in a reflectance spectrophotometer to evaluate the color changes using the CIE L*a*b* measuring system, after 7 and 28 days. The results were submitted to analysis of variance and Tukey tests.
  
  
  RESULTS
  There was no difference in the same material concerning the different storage conditions. Conventional glass ionomer cement, however, showed greater color stability in relation to resin-modified glass ionomer cement (P <.05) and to polyacid-modified resin composite (P<.01).
  
  
  CONCLUSIONS
  There were no significant color changes due to pH variations, and conventional glass ionomer cement presented greater color stability.
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil. jcpimparato@yahoo.com.br
authors.forename: José Carlos Pettorossi
authors.initials: JC
authors.lastname: Imparato
authors.forename: Anselmo
authors.initials: A
authors.lastname: Garcia
authors.forename: Clarissa Calil
authors.initials: CC
authors.lastname: Bonifácio
authors.forename: Lisa
authors.initials: L
authors.lastname: Scheidt
authors.forename: Daniela Prócida
authors.initials: DP
authors.lastname: Raggio
authors.forename: Fausto Medeiros
authors.initials: FM
authors.lastname: Mendes
authors.forename: Mário
authors.initials: M
authors.lastname: Vedovello Filho
mesh_terms: D000704:Analysis of Variance; D002327:Cariostatic Agents / Q000737:chemistry; D003116:Color; D003124:Colorimetry; D020770:Compomers / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003793:Dental Restoration, Permanent; D004356:Drug Storage; D004955:Esthetics, Dental; D005459:Fluorides / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D012464:Saliva, Artificial
chemical_list: D002327:Cariostatic Agents; C105428:Compoglass; D020770:Compomers; D003188:Composite Resins; D005899:Glass Ionomer Cements; D012464:Saliva, Artificial; C084550:Vitremer; C110713:fuji IX; D005459:Fluorides