title: Degradation of polymeric restorative materials subjected to a high caries challenge.
abstract: OBJECTIVE
  The aim of this study was to evaluate the degradation of different resin filling materials after a caries challenge, by high performance liquid chromatography (HPLC) and contact angle (θ) measurement.
  
  
  METHODS
  Four different polymeric restorative materials (a resin composite, a polyacid-modified resin composite, an ormocer and a resin-modified glass ionomer cement) were tested. Five samples (30 mm × 6 mm × 2 mm) of each material were formed in a Teflon mold, following the manufacturer's instructions. After pH cycles, the solutions were injected in an HPLC. The θ was obtained, before and after pH cycle, by a goniometer at 60% air humidity and 25°C. A distilled water drop (0.006 ml) was put on the material surface, and after 6 min, 10 measures were obtained at 20s intervals. Each sample received 4 drops, one at a time, on different areas.
  
  
  RESULTS
  HPLC results showed elution of byproducts in all materials. This was greater in the acid medium. Bis-GMA and TEGDMA were detected in TPH Spectrum and Definite residues. Analyses of the contact angle by ANOVA and Student-Neuman-Keuls's test showed that the surfaces of TPH Spectrum, Dyract AP and Definite were altered, except Vitremer (p<0.05).
  
  
  CONCLUSIONS
  All materials tested degraded on a caries simulated medium, suggesting that a great effort should be made to disseminate oral health information, since a high caries challenge environment (low pH) can lead to dental composite degradation, with potential toxic risks to patients.
authors.affiliation: Brazilian Navy, Navy Central Clinic, Rio de Janeiro, RJ, Brazil.
authors.forename: Márcio A P
authors.initials: MA
authors.lastname: Borges
authors.forename: Irma C
authors.initials: IC
authors.lastname: Matos
authors.forename: Luis C
authors.initials: LC
authors.lastname: Mendes
authors.forename: Ailton S
authors.initials: AS
authors.lastname: Gomes
authors.forename: Mauro S
authors.initials: MS
authors.lastname: Miranda
mesh_terms: D001711:Biotransformation; D017438:Bisphenol A-Glycidyl Methacrylate / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D020770:Compomers / Q000737:chemistry / Q000378:metabolism*; D003188:Composite Resins / Q000737:chemistry / Q000378:metabolism*; D003731:Dental Caries / Q000378:metabolism*; D003793:Dental Restoration, Permanent / Q000379:methods*; D005899:Glass Ionomer Cements / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008689:Methacrylates / Q000032:analysis; D011092:Polyethylene Glycols / Q000032:analysis; D011109:Polymethacrylic Acids / Q000032:analysis; D011140:Polyurethanes / Q000032:analysis; D013818:Thermogravimetry; D017155:Wettability
chemical_list: D020770:Compomers; D003188:Composite Resins; D005899:Glass Ionomer Cements; D008689:Methacrylates; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C084550:Vitremer; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate