title: The inhibition effect of non-protein thiols on dentinal matrix metalloproteinase activity and HEMA cytotoxicity.
abstract: OBJECTIVE
  Phosphoric acid (PA) etching used in etch-and-rinse adhesives is known to activate host-derived dentinal matrix-metalloproteinases (MMPs) and increase dentinal permeability. These two phenomena will result, respectively; in degradation of dentine-adhesive bond and leaching of some monomers especially 2-hydroxyethyl methacrylate (HEMA) into the pulp that would negatively affect the viability of pulpal cells. This study is the first to investigate the inhibitory effect of non-protein thiols (NPSH); namely reduced glutathione (GSH) and N-acetylcysteine (NAC) on dentinal MMPs and compare their effects on HEMA cytotoxicity.
  
  
  METHODS
  Dentine powder was prepared from human teeth, demineralized with 1% PA and then treated with 2% GSH, 2% NAC or 2% chlorhexidine (CHX). Zymographic analysis of extracted proteins was performed. To evaluate the effect of GSH, NAC and CHX on HEMA cytotoxicity, solutions of these compounds were prepared with or without HEMA and rat pulpal cells were treated with the tested solutions for (6 and 24h). Cells viability was measured by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytotoxicity data were analysed by one-way ANOVA and Tukey post hoc tests (p<0.05).
  
  
  RESULTS
  The inhibitory effect of GSH and NAC on dentinal MMPs was confirmed. GSH showed similar effectiveness to NAC regarding HEMA cytotoxicity inhibition.
  
  
  CONCLUSIONS
  NPSH were effective to inhibit dentinal MMPs and HEMA cytotoxicity.
  
  
  CONCLUSIONS
  The tested properties of NPSH provide promising clinical use of these agents which would enhance dentine-bond durability and decrease post-operative sensitivity.
authors: Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Global Center of Excellence (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases at Tokyo Medical and Dental University, Tokyo, Japan.
authors: Mohannad
authors: M
authors: Nassar
authors: Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: hiraope@tmd.ac.jp.
authors: Noriko
authors: N
authors: Hiraishi
authors: Pediatric Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Hitoyata
authors: H
authors: Shimokawa
authors: Pharmacology, Department of Hard Tissue Engineering, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Yukihiko
authors: Y
authors: Tamura
authors: Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Masayuki
authors: M
authors: Otsuki
authors: Oral Implantology and Regenerative Dental Medicine Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Shohei
authors: S
authors: Kasugai
authors: Pharmacology, Department of Hard Tissue Engineering, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Keiichi
authors: K
authors: Ohya
authors: Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Global Center of Excellence (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases at Tokyo Medical and Dental University, Tokyo, Japan.
authors: Junji
authors: J
authors: Tagami
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002710:Chlorhexidine / Q000494:pharmacology; D004396:Coloring Agents; D003764:Dental Materials / Q000633:toxicity*; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects*; D003804:Dentin / Q000201:enzymology*; D005978:Glutathione / Q000494:pharmacology*; D006801:Humans; D008422:Materials Testing; D020778:Matrix Metalloproteinase 2 / Q000187:drug effects; D061965:Matrix Metalloproteinase Inhibitors / Q000494:pharmacology*; D020782:Matrix Metalloproteinases / Q000187:drug effects*; D008689:Methacrylates / Q000633:toxicity*; D010756:Phosphoric Acids / Q000737:chemistry; D051381:Rats; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D000891:Anti-Infective Agents, Local; D004396:Coloring Agents; D003764:Dental Materials; D061965:Matrix Metalloproteinase Inhibitors; D008689:Methacrylates; D010756:Phosphoric Acids; D013778:Tetrazolium Salts; D013844:Thiazoles; C005044:hydroxyethyl methacrylate; C030242:phosphoric acid; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; C522363:Mmp2 protein, rat; C022616:thiazolyl blue; D005978:Glutathione; D002710:Chlorhexidine; D000111:Acetylcysteine
keywords: Cytotoxicity; Dentine; Glutathione; HEMA; Matrix metalloproteinase; N-acetylcysteine; Non-protein thiols