title: Substantivity of chlorhexidine to human dentin.
abstract: OBJECTIVE
  To better comprehend the role of CHX in the preservation of resin-dentin bonds, this study investigated the substantivity of CHX to human dentin.
  
  
  METHODS
  Dentin disks (n=45) were obtained from the mid-coronal portion of human third molars. One-third of dentin disks were kept mineralized (MD), while the other two-thirds had one of the surfaces partially demineralized with 37% phosphoric acid for 15 s (PDD) or they were totally demineralized with 10% phosphoric acid (TDD). Disks of hydroxyapatite (HA) were also prepared. Specimens were treated with: (1) 10 microL of distilled water (controls), (2) 10 microL of 0.2% chlorhexidine diacetate (0.2% CHX) or (3) 10 microL of 2% chlorhexidine diacetate (2% CHX). Then, they were incubated in 1 mL of PBS (pH 7.4, 37 degrees C). Substantivity was evaluated as a function of the CHX-applied dose after: 0.5 h, 1 h, 3 h, 6 h, 24 h, 168 h (1 week), 672 h (4 weeks) and 1344 h (8 weeks) of incubation. CHX concentration in eluates was spectrophotometrically analyzed at 260 nm.
  
  
  RESULTS
  Significant amounts of CHX remained retained in dentin substrates (MD, PPD or TDD), independent on the CHX-applied dose or time of incubation (p<0.05). High amounts of retained CHX onto HA were observed only for specimens treated with the highest concentration of CHX (2%) (p<0.05).
  
  
  CONCLUSIONS
  The outstanding substantivity of CHX to dentin and its reported effect on the inhibition of dentinal proteases may explain why CHX can prolong the durability of resin-dentin bonds.
authors.affiliation: GEO/UNIBAN, Health Institute, Bandeirante University of São Paulo, São Paulo, Brazil.
authors.forename: Marcela R
authors.initials: MR
authors.lastname: Carrilho
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Carvalho
authors.forename: Ethan N
authors.initials: EN
authors.lastname: Sousa
authors.forename: José
authors.initials: J
authors.lastname: Nicolau
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
authors.forename: Annalisa
authors.initials: A
authors.lastname: Mazzoni
authors.forename: Leo
authors.initials: L
authors.lastname: Tjäderhane
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Kelli
authors.initials: K
authors.lastname: Agee
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D000704:Analysis of Variance; D000891:Anti-Infective Agents, Local / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D002710:Chlorhexidine / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D001840:Dental Bonding; D003804:Dentin / Q000378:metabolism*; D017886:Durapatite / Q000378:metabolism; D006801:Humans; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors / Q000494:pharmacology; D011485:Protein Binding; D017001:Tooth Demineralization / Q000378:metabolism*
chemical_list: D000891:Anti-Infective Agents, Local; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D017886:Durapatite; D002710:Chlorhexidine
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