title: Effect of a novel quaternary ammonium silane on dentin protease activities.
abstract: OBJECTIVE
  Demineralized dentin collagen release C-terminal cross-linked telopeptide (ICTP) and C-terminal peptide (CTX) during degradation. The present study evaluated the effects of dentin pre-treatment with K21, a quaternary ammonium silane (QAS), on matrix metalloproteinase (MMP) and cathepsin K-mediated collagen degradation.
  
  
  METHODS
  Dentin beams were demineralized with 10% H3PO4for 24h. After baseline dry mass measurements, the beams were divided into 5 groups (N=10) according to protease inhibitors. The beams were pre-treated for 2min with 2% chlorhexidine (CHX), 2%, 5% or 10% QAS; no pre-treatment was performed for the control group. The beams were subsequently incubated in calcium- and zinc-containing medium for 3, 7 or 14days, after which changes in dry mass were measured and incubation media were examined for ICTP and CTX release. The MMP-2 and cathepsin K activities in QAS-treated dentin powder were also quantified using ELISA.
  
  
  RESULTS
  The two factors (disinfectants and time) had a significant effect on dry mass loss, ICTP and CTX release (p<0.001). The percentage of dry mass loss increased with time and was significantly lower in all experimental groups when compared to the control at 14days (p<0.001). Conversely, the rate of ICTP and CTX release was significantly lower in the experimental groups, compared to the uninhibited control at 7 and 14days (p<0.001). Dentinal MMP-2 and cathepsin K activities were significantly reduced after demineralized dentin was pre-treated with QAS.
  
  
  CONCLUSIONS
  The experimental QAS is a good inhibitor of MMP and cathepsin K activities in demineralized dentin.
  
  
  CONCLUSIONS
  The newly developed antibacterial quaternary ammonium silane increases the resistance of dentin collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The quaternary ammonium silane cavity disinfectant is promising for use as a protease inhibitor to improve durability of resin-dentin bonds.
authors.affiliation: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Pokfulam, Hong Kong SAR, China.
authors.forename: D
authors.initials: D
authors.lastname: Umer
authors.affiliation: Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Pokfulam, Hong Kong SAR, China. Electronic address: ckyyiu@hkucc.hku.hk.
authors.forename: C K Y
authors.initials: CK
authors.lastname: Yiu
authors.affiliation: Melbourne Dental School, The University of Melbourne, Australia.
authors.forename: M F
authors.initials: MF
authors.lastname: Burrow
authors.affiliation: State Key Laboratory of Military Stomatology, Fourth Military Medical University, Xi'an, Shaanxi, PR China.
authors.forename: L-N
authors.initials: LN
authors.lastname: Niu
authors.affiliation: Department of Endodontics, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA.
authors.forename: F R
authors.initials: FR
authors.lastname: Tay
mesh_terms: D000293:Adolescent; D002118:Calcium / Q000032:analysis; D056657:Cathepsin K / Q000187:drug effects*; D002710:Chlorhexidine / Q000494:pharmacology; D024042:Collagen Type I / Q000378:metabolism; D003804:Dentin / Q000737:chemistry / Q000187:drug effects*; D006723:Hong Kong; D006801:Humans; D006868:Hydrolysis / Q000187:drug effects; D020778:Matrix Metalloproteinase 2 / Q000187:drug effects; D020782:Matrix Metalloproteinases / Q000187:drug effects*; D008964:Molar, Third; D010455:Peptides / Q000378:metabolism; D010756:Phosphoric Acids / Q000009:adverse effects; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D012821:Silanes / Q000008:administration & dosage / Q000494:pharmacology*; D017001:Tooth Demineralization / Q000378:metabolism; D055815:Young Adult; D015032:Zinc / Q000032:analysis
chemical_list: D024042:Collagen Type I; C093073:Demineralized Dentin Matrix; C000624400:K21 compound; D010455:Peptides; D010756:Phosphoric Acids; D000644:Quaternary Ammonium Compounds; D012821:Silanes; C052929:collagen type I trimeric cross-linked peptide; D056657:Cathepsin K; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D015032:Zinc; D002710:Chlorhexidine; D002118:Calcium
keywords: Cysteine cathepsins; Dentin; Matrix metalloproteinases; Quaternary ammonium silane