title: Novel dental adhesives containing nanoparticles of silver and amorphous calcium phosphate.
abstract: OBJECTIVE
  Secondary caries is the main reason for restoration failure, and replacement of the failed restorations accounts for 50-70% of all restorations. Antibacterial adhesives could inhibit residual bacteria in tooth cavity and invading bacteria along the margins. Calcium (Ca) and phosphate (P) ion release could remineralize the lesions. The objectives of this study were to incorporate nanoparticles of silver (NAg) and nanoparticles of amorphous calcium phosphate (NACP) into adhesive for the first time, and to investigate the effects on dentin bond strength and plaque microcosm biofilms.
  
  
  METHODS
  Scotchbond multi-purpose adhesive was used as control. NAg were added into primer and adhesive at 0.1% by mass. NACP were mixed into adhesive at 10%, 20%, 30% and 40%. Microcosm biofilms were grown on disks with primer covering the adhesive on a composite. Biofilm metabolic activity, colony-forming units (CFU) and lactic acid were measured.
  
  
  RESULTS
  Human dentin shear bond strengths (n=10) ranged from 26 to 34 MPa; adding NAg and NACP into adhesive did not decrease the bond strength (p>0.1). SEM examination revealed resin tags from well-filled dentinal tubules. Numerous NACP infiltrated into the dentinal tubules. While NACP had little antibacterial effect, NAg in bonding agents greatly reduced the biofilm viability and metabolic activity, compared to the control (p<0.05). CFU for total microorganisms, total streptococci, and mutans streptococci on bonding agents with NAg were an order of magnitude less than those of the control. Lactic acid production by biofilms for groups containing NAg was 1/4 of that of the control.
  
  
  CONCLUSIONS
  Dental plaque microcosm biofilm viability and acid production were greatly reduced on bonding agents containing NAg and NACP, without compromising dentin bond strength. The novel method of incorporating dual agents (remineralizing agent NACP and antibacterial agent NAg) may have 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: Mary Anne S
authors.initials: MA
authors.lastname: Melo
authors.forename: Lei
authors.initials: L
authors.lastname: Cheng
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.forename: Michael D
authors.initials: MD
authors.lastname: Weir
authors.forename: Lidiany K A
authors.initials: LK
authors.lastname: Rodrigues
authors.forename: Hockin H K
authors.initials: HH
authors.lastname: Xu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002130:Calcium Phosphates; D003188:Composite Resins / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry* / Q000494:pharmacology; D003773:Dental Plaque / Q000382:microbiology; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry* / Q000494:pharmacology; D033081:Shear Strength / Q000187:drug effects; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology; D013234:Stem Cells / Q000378:metabolism
chemical_list: D000180:Acrylic Resins; D000900:Anti-Bacterial Agents; D002130:Calcium Phosphates; C029012:Composite Dental Resin; D003188:Composite Resins; D003738:Dental Cements; D011140:Polyurethanes; D019279:Resin Cements; C519480:amorphous calcium phosphate; D019344:Lactic Acid; D012834:Silver; C041330:Scotchbond