title: Degradation of resin composites in a simulated deep cavity.
abstract: The aim of this study was to analyze the sorption and solubility of a nanofilled (Filtek Z350) and a midifilled (Filtek P60) resin composite in oral environment-like substances, in a simulated deep cavity. A cylindrical cavity prepared in a bovine incisor root was incrementally filled with resin composites. The obtained resin composite cylinders were cut perpendicularly to the axis to obtain 1-mm-thick discs that were divided into fifteen groups (n=5) according to depth (1, 2, 3, 4 and 5 mm) and immersion media (distilled water - DW, artificial saliva - AS and lactic acid - LA). The sorption and solubility were calculated based on ISO 4049:2000. Additionally, the degree of conversion (DC%) was calculated by FT-IR spectroscopy. Data were analyzed using multifactor analysis of variance (MANOVA) followed by Tukey's HSD post-hoc test and linear regression analysis (a=0.05). The DC% was higher for the midifilled resin composite and was negatively influenced by cavity depth (p<0.05). The nanofilled resin composite presented higher sorption and solubility than did the midifilled (p<0.05). The immersion media influenced the sorption and the solubility as follows: LA>AS>DW, (p<0.05). Both phenomena were influenced by cavity depth, with the sorption and solubility increasing from 1 to 5 mm (p<0.05). The degradation of resin composite restorations may be greater in the deepest regions of class II restorations when the composite is exposed to organic acids present in the oral biofilm (lactic acid).
authors.affiliation: Analytical Laboratory of Restorative Biomaterials - LABiom-R, Dental School, UFF - Fluminense Federal University, Niterói, RJ, Brazil.
authors.forename: Luana
authors.initials: L
authors.lastname: Gonçalves
authors.affiliation: Analytical Laboratory of Restorative Biomaterials - LABiom-R, Dental School, UFF - Fluminense Federal University, Niterói, RJ, Brazil.
authors.forename: Cristiane Mariote
authors.initials: CM
authors.lastname: Amaral
authors.affiliation: Analytical Laboratory of Restorative Biomaterials - LABiom-R, Dental School, UFF - Fluminense Federal University, Niterói, RJ, Brazil.
authors.forename: Laiza Tatiana
authors.initials: LT
authors.lastname: Poskus
authors.affiliation: Analytical Laboratory of Restorative Biomaterials - LABiom-R, Dental School, UFF - Fluminense Federal University, Niterói, RJ, Brazil.
authors.forename: José Guilherme Antunes
authors.initials: JG
authors.lastname: Guimarães
authors.affiliation: Analytical Laboratory of Restorative Biomaterials - LABiom-R, Dental School, UFF - Fluminense Federal University, Niterói, RJ, Brazil.
authors.forename: Eduardo Moreira da
authors.initials: EM
authors.lastname: Silva
mesh_terms: D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D006244:Hardness; D006868:Hydrolysis; D066298:In Vitro Techniques; D007700:Kinetics; D008422:Materials Testing; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012464:Saliva, Artificial / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D012387:Root Canal Filling Materials; D012464:Saliva, Artificial; C533204:filtek Z350; D014867:Water