title: The diffusion kinetics of a nanofilled and a midifilled resin composite immersed in distilled water, artificial saliva, and lactic acid.
abstract: This study investigated the diffusion kinetics of a nanofilled (Filtek Z350) and a midifill (Filtek P60) resin composite immersed in distilled water, artificial saliva and lactic acid. Resin composite specimens were desiccated, immersed in the media, weighed at suitable time intervals until they reached sorption equilibrium and were then desiccated again. Sorption and solubility (µg/mm(3)) were calculated based on ISO 4049:2000(E). The diffusion coefficient (m(2).s(-1)) was determined according to Flick's second law. The degree of conversion (DC%) was evaluated by FT-IR and the action of the media on the surfaces of the resin composite was evaluated by SEM. Z350 immersed in lactic acid presented the highest sorption (25.9 ± 1.3). The highest solubility was presented by Z350 immersed in lactic acid (5.6 ± 0.9), followed by P60 immersed in lactic acid (4.4 ± 0.5). The other groups presented no significant difference among them. The diffusion coefficients of both resin composites immersed in lactic acid and that of Z350 immersed in artificial saliva were significantly higher. The lowest diffusion coefficient was presented by P60 immersed in distilled water. The DC% was not significant, (p > 0.05). The SEM analysis showed that the effect of lactic acid on the resin composites was more deleterious than those of water and artificial saliva.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal Fluminense University, Niterói, Rio de Janeiro, Brazil. emsilva@vm.uff.br
authors.forename: Eduardo Moreira
authors.initials: EM
authors.lastname: da Silva
authors.forename: Luana
authors.initials: L
authors.lastname: Gonçalves
authors.forename: José Guilherme Antunes
authors.initials: JG
authors.lastname: Guimarães
authors.forename: Laiza Tatiana
authors.initials: LT
authors.lastname: Poskus
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Fellows
mesh_terms: D000042:Absorption; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D004058:Diffusion; D006244:Hardness; D006868:Hydrolysis; D007700:Kinetics; D019344:Lactic Acid; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry; D058105:Polymerization; D012464:Saliva, Artificial; D012995:Solubility; D018709:Statistics, Nonparametric; D014867:Water
chemical_list: D003188:Composite Resins; C443708:P60 Condensible Resin Composite; D012464:Saliva, Artificial; C533204:filtek Z350; D014867:Water; D019344:Lactic Acid