title: Effects of age condition on the distribution and integrity of inorganic fillers in dental resin composites.
abstract: OBJECTIVE
  The aim of this study is to evaluate the distribution of the filler size along with the zeta potential, and the integrity of silane-bonded filler surface in different types of restorative dental composites as a function of the material age condition.
  
  
  METHODS
  Filtek P60 (hybrid composite), Filtek Z250 (small-particle filled composite), Filtek Z350XT (nanofilled composite), and Filtek Silorane (silorane composite) (3M ESPE) were tested at different stage condition (i.e., fresh/new, aged, and expired). Composites were submitted to an accelerated aging protocol (Arrhenius model). Specimens were obtained by first diluting each composite specimen in ethanol and then dispersed in potassium chloride solution (0.001 mol%). Composite fillers were characterized for their zeta potential, mean particle size, size distribution, via poly-dispersion dynamic light scattering. The integrity of the silane-bonded surface of the fillers was characterized by FTIR.
  
  
  RESULTS
  The material age influenced significantly the outcomes; Zeta potential, filler characteristics, and silane integrity varied both after aging and expiration. Silorane presented the broadest filler distribution and lowest zeta potential. Nanofilled and silorane composites exhibited decreased peak intensities in the FTIR analysis, indicating a deficiency of the silane integrity after aging or expiry time.
  
  
  CONCLUSIONS
  Regardless to the material condition, the hybrid and the small-particle-filled composites were more stable overtime as no significant alteration in filler size distribution, diameter, and zeta potential occurred. A deficiency in the silane integrity in the nanofilled and silorane composites seems to be affected by the material stage condition.
  
  
  CONCLUSIONS
  The materials conditions tested in this study influenced the filler size distribution, the zeta potential, and integrity of the silane adsorbed on fillers in the nanofilled and silorane composites. Thus, this may result in a decrease of the clinical performance of aforementioned composites, in particular, if these are used after inappropriate storage conditions.
authors.affiliation: Biomaterials Research Group, School of Dentistry, Universidade Anhanguera de São Paulo (UNIAN - SP), Rua Maria Cândida, 1813, São Paulo, SP, Brazil, CEP 02071-013. paulodalpino@yahoo.com.
authors.forename: Paulo Henrique Perlatti
authors.initials: PH
authors.lastname: D'Alpino
authors.affiliation: Hospital de Reabilitação de Anomalias Craniofaciais (HRAC-USP), Universidade de São Paulo, Bauru, SP, Brazil.
authors.forename: Nádia da Rocha
authors.initials: Nda R
authors.lastname: Svizero
authors.affiliation: Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Odair
authors.initials: O
authors.lastname: Bim Júnior
authors.affiliation: Department of Pharmacy and Biotechnology, Universidade Anhanguera de São Paulo (UNIAN - SP), São Paulo, SP, Brazil.
authors.forename: Claudete Justina
authors.initials: CJ
authors.lastname: Valduga
authors.affiliation: DF-FC, UNESP - Universidade Estadual Paulista, POSMAT - Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Bauru, SP, Brazil.
authors.forename: Carlos Frederico de Oliveira
authors.initials: CF
authors.lastname: Graeff
authors.affiliation: Dental Biomaterials and Minimally Invasive Dentistry, Departamento de Odontología, Facultad de Ciencias de la Salud, Universidad CEU Cardenal Herrera, Valencia, Spain.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sauro
mesh_terms: D003188:Composite Resins / Q000737:chemistry; D003799:Dental Stress Analysis; D008422:Materials Testing; D010316:Particle Size; D062047:Silorane Resins / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins; C438835:Filtek P60 Composite Resin; C444701:Filtek Z250; D062047:Silorane Resins; C533204:filtek Z350; C555513:silorane composite resin
keywords: Aging; Dynamic light scattering; Filler sizing distribution; Methacrylate; Resin composites; Silorane; Zeta potential