title: An antifungal coating for dental silicones composed of chlorhexidine nanoparticles.
abstract: OBJECTIVE
  The aims of this study were to synthesise a range of chlorhexidine-containing nanoparticles (CHX-NPs), and investigate the feasibility of using these as an antifungal coating for dental silicones.
  
  
  METHODS
  CHX-NPs were precipitated in aqueous reaction by mixing solutions of CHX digluconate with solutions of sodium triphosphate (TP), trimetaphosphate (TMP) or hexametaphosphate (HMP). CHX-NPs were deposited on commercial dental silicones by immersion coating, and these were characterised for hydrophilicity (contact angle) and water uptake (mass change). Soluble CHX elution into artificial saliva was measured using ultraviolet spectrophotometry. Antifungal efficacy against Candida albicans was investigated using a cell proliferation assay.
  
  
  RESULTS
  Coating silicones with CHX-NPs did not significantly affect hydrophilicity, as assessed using water contact angle, or water uptake as assessed by mass change following 16 weeks' immersion in artificial saliva. CHX-NP-coated silicone specimens released soluble CHX into artificial saliva. The salt of CHX and the immersion time affected the rate, concentration and duration of CHX release, with CHX-HMP exhibiting a slow, sustained release and CHX-TP and CHX-TMP exhibiting a faster, more concentrated release. C. albicans metabolic activity was inhibited by presence of CHX-HMP-NPs in suspension.
  
  
  CONCLUSIONS
  CHX-NPs provided a localised, controlled dose of soluble CHX at the surface of dental silicones without adversely affecting hydrophilicity or water uptake. CHX-HMP NPs provided effective antifungal control of C. albicans in a cell proliferation assay. Coating materials with these nanoparticles could be an effective way of delivering low, but clinically relevant, concentrations of chlorhexidine in the oral environment.
  
  
  CONCLUSIONS
  Denture stomatitis is a common oral infection and is associated with fungal infestation of denture soft lining and obturator materials, which are often silicones such as those used here. Our study suggests that CHX-NPs may be a useful strategy in design of antifungal coatings for these materials.
authors.affiliation: Oral Nanoscience, School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Garner
authors.affiliation: Microbiology, Oral Microbiology, School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors.forename: Angela H
authors.initials: AH
authors.lastname: Nobbs
authors.affiliation: Restorative Dentistry, School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: McNally
authors.affiliation: Oral Nanoscience, School of Oral and Dental Sciences, University of Bristol, Bristol, UK. Electronic address: M.E.Barbour@bristol.ac.uk.
authors.forename: Michele E
authors.initials: ME
authors.lastname: Barbour
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002710:Chlorhexidine / Q000494:pharmacology*; D003764:Dental Materials / Q000737:chemistry; D003822:Denture Liners; D008826:Microbial Sensitivity Tests; D053758:Nanoparticles; D012828:Silicones
chemical_list: D000935:Antifungal Agents; D003764:Dental Materials; D012828:Silicones; D002710:Chlorhexidine
keywords: Candida albicans; Chlorhexidine; Denture; Nanoparticles; Obturator