title: Effect of quaternary ammonium and silver nanoparticle-containing adhesives on dentin bond strength and dental plaque microcosm biofilms.
abstract: OBJECTIVE
  Antibacterial bonding agents are promising to hinder the residual and invading bacteria at the tooth-restoration interfaces. The objectives of this study were to develop an antibacterial bonding agent by incorporation of quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effect of QADM-NAg adhesive and primer on dentin bond strength and plaque microcosm biofilm response for the first time.
  
  
  METHODS
  Scotchbond Multi-Purpose adhesive and primer were used as control. Experimental adhesive and primer were made by adding QADM and NAg into control adhesive and primer. Human dentin shear bond strengths were measured (n = 10). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production, and live/dead staining assay (n = 6).
  
  
  RESULTS
  Adding QADM and NAg into adhesive and primer did not compromise the dentin shear bond strength which ranged from 30 to 35MPa (p>0.1). Scanning electron microscopy (SEM) examinations revealed numerous resin tags, which were similar for the control and the QADM and NAg groups. Adding QADM or NAg markedly reduced the biofilm viability, compared to adhesive control. QADM and NAg together in the adhesive had a much stronger antibacterial effect than using each agent alone (p<0.05). Adding QADM and NAg in both adhesive and primer had the strongest antibacterial activity, reducing metabolic activity, CFU, and lactic acid by an order of magnitude, compared to control.
  
  
  CONCLUSIONS
  Without compromising dentin bond strength and resin tag formation, the QADM and NAg containing adhesive and primer achieved strong antibacterial effects against microcosm biofilms for the first time. QADM-NAg adhesive and primer are promising to combat residual bacteria in tooth cavity and invading bacteria at the margins, thereby to inhibit secondary caries. QADM and NAg incorporation may have a wide applicability to other dental bonding systems.
authors.affiliation: Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.forename: Mary Anne S
authors.initials: MA
authors.lastname: Melo
authors.forename: Lei
authors.initials: L
authors.lastname: Cheng
authors.forename: Michael D
authors.initials: MD
authors.lastname: Weir
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Bai
authors.forename: Hockin H K
authors.initials: HH
authors.lastname: Xu
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects*; D015169:Colony Count, Microbial; D001840:Dental Bonding; D003763:Dental Leakage / Q000517:prevention & control; D003773:Dental Plaque / Q000378:metabolism*; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008422:Materials Testing; D050296:Microbial Viability / Q000187:drug effects; D008963:Molar; D053758:Nanoparticles; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000494:pharmacology; D019279:Resin Cements / Q000737:chemistry* / Q000494:pharmacology; D012463:Saliva / Q000382:microbiology; D033081:Shear Strength; D018030:Silver Compounds / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D017220:Dentin-Bonding Agents; D000644:Quaternary Ammonium Compounds; D019279:Resin Cements; D018030:Silver Compounds; D019344:Lactic Acid