Antibacterial and physical properties of calcium-phosphate and calcium-fluoride nanocomposites with chlorhexidine.
OBJECTIVE
Previous studies have developed calcium phosphate and fluoride releasing composites. Other studies have incorporated chlorhexidine (CHX) particles into dental composites. However, CHX has not been incorporated in calcium phosphate and fluoride composites. The objectives of this study were to develop nanocomposites containing amorphous calcium phosphate (ACP) or calcium fluoride (CaF(2)) nanoparticles and CHX particles, and investigate Streptococcus mutans biofilm formation and lactic acid production for the first time.


METHODS
Chlorhexidine was frozen via liquid nitrogen and ground to obtain a particle size of 0.62 μm. Four nanocomposites were fabricated with fillers of: nano ACP; nano ACP+10% CHX; nano CaF(2); nano CaF(2)+10% CHX. Three commercial materials were tested as controls: a resin-modified glass ionomer, and two composites. S. mutans live/dead assay, colony-forming unit (CFU) counts, biofilm metabolic activity, and lactic acid were measured.


RESULTS
Adding CHX fillers to ACP and CaF(2) nanocomposites greatly increased their antimicrobial capability. ACP and CaF(2) nanocomposites with CHX that were inoculated with S. mutans had a growth medium pH>6.5 after 3 d, while the control commercial composites had a cariogenic pH of 4.2. Nanocomposites with CHX reduced the biofilm metabolic activity by 10-20 folds and reduced the acid production, compared to the controls. CFU on nanocomposites with CHX were three orders of magnitude less than that on commercial composite. Mechanical properties of nanocomposites with CHX matched a commercial composite without fluoride.


CONCLUSIONS
The novel calcium phosphate and fluoride nanocomposites could be rendered antibacterial with CHX to greatly reduce biofilm formation, acid production, CFU and metabolic activity. The antimicrobial and remineralizing nanocomposites with good mechanical properties may be promising for a wide range of tooth restorations with anti-caries capabilities.
Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, 21201, USA.
Lei
L
Cheng
Michael D
MD
Weir
Hockin H K
HH
Xu
Alison M
AM
Kraigsley
Nancy J
NJ
Lin
Sheng
S
Lin-Gibson
Xuedong
X
Zhou
D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002124:Calcium Fluoride / Q000737:chemistry / Q000494:pharmacology*; D002130:Calcium Phosphates / Q000737:chemistry / Q000494:pharmacology*; D002710:Chlorhexidine / Q000737:chemistry / Q000494:pharmacology*; D003188:Composite Resins / Q000737:chemistry / Q000494:pharmacology*; D003764:Dental Materials / Q000737:chemistry / Q000494:pharmacology*; D004058:Diffusion; D005615:Freezing; D005898:Glass / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000032:analysis; D008422:Materials Testing; D050296:Microbial Viability / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry*; D010316:Particle Size; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013295:Streptococcus mutans / Q000187:drug effects; D013314:Stress, Mechanical
D000900:Anti-Bacterial Agents; D002130:Calcium Phosphates; D003188:Composite Resins; D003764:Dental Materials; D005899:Glass Ionomer Cements; D011109:Polymethacrylic Acids; D019279:Resin Cements; C519480:amorphous calcium phosphate; C020946:triethylene glycol dimethacrylate; D019344:Lactic Acid; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D002124:Calcium Fluoride; D002710:Chlorhexidine