title: Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode.
abstract: Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle.
  
  
  OBJECTIVE
  To investigate the degradation of four resin-based cements: Rely X ARC (R), Variolink II (V), Enforce (E) and All Cem (A), after immersion in distilled water (DW), lactic acid (LA) and artificial saliva (AS) and to analyze the influence of the activation mode on this response.
  
  
  METHODS
  Two activation modes were evaluated: chemical (Ch) and dual (D). In the dual activation, a two-millimeter thick ceramic disk (IPS Empress System) was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37°C for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm 3 ) were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA) and Tukey's HSD test for media comparisons (α=0.05).
  
  
  RESULTS
  Sorption was higher after immersion in LA (p<0.05) and increased significantly with time (p<0.05). Sorption was influenced by the activation mode: Ch>D (p<0.05). The lowest solubility was presented by R (p<0.05).
  
  
  CONCLUSIONS
  Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements.
authors.affiliation: Analytical Laboratory of Restorative Biomaterials - LABiom-R, School of Dentistry, Federal Fluminense University, Niterói, RJ, Brazil. emsilva@vm.uff.br
authors.forename: Eduardo Moreira da
authors.initials: EM
authors.lastname: Silva
authors.forename: Jaime Dutra
authors.initials: JD
authors.lastname: Noronha-Filho
authors.forename: Cristiane Mariote
authors.initials: CM
authors.lastname: Amaral
authors.forename: Laiza Tatiana
authors.initials: LT
authors.lastname: Poskus
authors.forename: José Guilherme Antunes
authors.initials: JG
authors.lastname: Guimarães
mesh_terms: D000042:Absorption; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D055117:Curing Lights, Dental; D006801:Humans; D007101:Immersion; D019344:Lactic Acid / Q000737:chemistry; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D012464:Saliva, Artificial / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C103503:EnForce-Sure Cure; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; D012464:Saliva, Artificial; D014867:Water; C103502:Variolink; D019344:Lactic Acid; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate