title: Comparison of microleakage on one composite etched with phosphoric acid or a combination of phosphoric and hydrofluoric acids and bonded with several different systems.
abstract: BACKGROUND
  There are no data available on whether or to what extent hydrofluoric acid affects the marginal integrity of dentin-bonded composite restorations when it is used instead of phosphoric acid in the total-etch technique.
  
  
  OBJECTIVE
  This in vitro study examined the etching effects of phosphoric acid versus a combination of phosphoric and hydrofluoric acid by evaluation of microleakage in a composite restoration bonded with different dentin adhesive systems.
  
  
  METHODS
  Extracted teeth (n = 90) containing 2 class II preparations, mesial occlusal (MO) and distal occlusal (DO) standarized (cervical margins in dentin) were perfused with Ringer solution and etched in 1 of 2 ways: with phosphoric acid only or with phosphoric combined with hydrofluoric acid. Different dentin bonding agents were then applied (Etch & Prime 3.0, Optibond Solo, Prime & Bond NT, Scotchbond 1, Syntac Single Component, or Syntac Sprint; (n = 15 for each etching material)). The preparations were restored with a hybrid composite (Herculite XRV) and submitted to 5000 thermocycles (5 degrees C to 55 degrees C) to simulate the in vivo situation. Microleakage was assessed with 2% methylene blue diffusion for 24 hours. Dye penetration was calculated as a percentage of the total length of the gingival margins of the preparation with light microscopy at original magnification x 32. The results were analyzed with the Kruskal-Wallis multiple comparison z-value assay (alpha = .05).
  
  
  RESULTS
  Differences in dye penetration were significant, both as a function of the dentin adhesive and the conditioning mode applied. In the specimen groups conditioned with phosphoric acid, Optibond Solo (54% +/- 44%) and Syntac Sprint (74% +/- 39%) demonstrated the lowest penetration values. Higher values were obtained for Prime & Bond NT (81% +/- 34%), Scotchbond 1 (83% +/- 31%), Etch & Prime 3.0 (85% +/- 33%), and Syntac Single Component (95% +/- 16%), with no significant differences (alpha=.05) between specimen groups. The best results were obtained for Syntac Sprint (24% +/- 26% dye penetration) after conditioning with a mixture of phosphoric and hydrofluoric acid. The least favorable result was obtained for Optibond Solo (65% +/- 31%). It was significantly different from Prime & Bond NT (76% +/- 37%), Scotchbond 1 (85% +/- 29%), and Etch & Prime 3.0 (88% +/- 24%). Syntac Single Component (75% +/- 32%) was significantly different from Syntac Sprint. Syntac Single Component and Syntac Sprint exhibited significantly better results when conditioned with a combination of phosphoric acid and hydrofluoric acid than with phosphoric acid only.
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, total-etching water-based (Syntac Single Component) and acetone-based (Syntac Sprint) bonding agents with a combination of phosphoric acid and hydrofluoric acid led to significant reductions (alpha=.05) in dye penetration compared to phosphoric acid conditioning only. Ethanol-based dentin bonding agents (Etch & Prime 3.0, Optibond Solo, and Scotchbond 1) were not significantly influenced by the type of conditioner used.
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Johann Wolfgang Goethe University, Frankfurt am Main, Germany. s.szep@em.uni-frankfurt.de
authors.forename: Susanne
authors.initials: S
authors.lastname: Szep
authors.forename: Nicole
authors.initials: N
authors.lastname: Langner
authors.forename: Silja
authors.initials: S
authors.lastname: Bayer
authors.forename: Diana
authors.initials: D
authors.lastname: Börnichen
authors.forename: Christoph
authors.initials: C
authors.lastname: Schulz
authors.forename: Thomas
authors.initials: T
authors.lastname: Gerhardt
authors.forename: Anette
authors.initials: A
authors.lastname: Schriever
authors.forename: Joachim
authors.initials: J
authors.lastname: Becker
authors.forename: Detlef
authors.initials: D
authors.lastname: Heidemann
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000179:Acrylates; D017438:Bisphenol A-Glycidyl Methacrylate; D003763:Dental Leakage; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D003804:Dentin / Q000187:drug effects; D017220:Dentin-Bonding Agents; D011756:Diphosphates; D000431:Ethanol; D006801:Humans; D006858:Hydrofluoric Acid / Q000494:pharmacology; D008298:Maleates; D008689:Methacrylates; D010756:Phosphoric Acids / Q000494:pharmacology; D011109:Polymethacrylic Acids; D019279:Resin Cements; D018709:Statistics, Nonparametric
chemical_list: D000179:Acrylates; D017220:Dentin-Bonding Agents; D011756:Diphosphates; C121187:Etch&Prime; D008298:Maleates; D008689:Methacrylates; C428805:OptiBond SOLO; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C443859:Syntac Sprint; C078484:Syntac dentine adhesive; C065770:Herculite XR; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate; C041330:Scotchbond; C030242:phosphoric acid; D006858:Hydrofluoric Acid