title: Novel rechargeable calcium phosphate dental nanocomposite.
abstract: OBJECTIVE
  Calcium phosphate (CaP) composites with Ca and P ion release can remineralize tooth lesions and inhibit caries. But the ion release lasts only a few months. The objectives of this study were to develop rechargeable CaP dental composite for the first time, and investigate the Ca and P recharge and re-release of composites with nanoparticles of amorphous calcium phosphate (NACP) to achieve long-term inhibition of caries.
  
  
  METHODS
  Three NACP nanocomposites were fabricated with resin matrix of: (1) bisphenol A glycidyl dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) at 1:1 mass ratio (referred to as BT group); (2) pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA) at 1:1 ratio (PE group); (3) BisGMA, TEGDMA, and Bis[2-(methacryloyloxy)ethyl] phosphate (BisMEP) at 2:1:1 ratio (BTM group). Each resin was filled with 20% NACP and 50% glass particles, and the composite was photo-cured. Specimens were tested for flexural strength and elastic modulus, Ca and P ion release, and Ca and P ion recharge and re-release.
  
  
  RESULTS
  NACP nanocomposites had strengths 3-fold of, and elastic moduli similar to, commercial resin-modified glass ionomer controls. CaP ion recharge capability was the greatest for PE group, followed by BTM group, with BT group being the lowest (p<0.05). For each recharge cycle, CaP re-release reached similarly high levels, showing that CaP re-release did not decrease with more recharge cycles. After six recharge/re-release cycles, NACP nanocomposites without further recharge had continuous CaP ion release for 42 d.
  
  
  CONCLUSIONS
  Novel rechargeable CaP composites achieved long-term and sustained Ca and P ion release. Rechargeable NACP nanocomposite is promising for caries-inhibiting restorations, and the Ca and P ion recharge and re-release method has wide applicability to dental composites, adhesives, cements and sealants to achieve long-term caries-inhibition.
authors.affiliation: State Key laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an 710032, China; Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Weir
authors.affiliation: Dr Anthony Volpe Research Center, American Dental Association Foundation (ADAF), National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Laurence C
authors.initials: LC
authors.lastname: Chow
authors.affiliation: Biomaterials Group, Biosystems & Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Antonucci
authors.affiliation: State Key laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Jihua
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA; Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Mechanical Engineering, University of Maryland, Baltimore County, MD 21250, USA. Electronic address: hxu@umaryland.edu.
authors.forename: Hockin H K
authors.initials: HH
authors.lastname: Xu
mesh_terms: D001565:Benzoates / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry*; D003188:Composite Resins / Q000138:chemical synthesis / Q000737:chemistry*; D003731:Dental Caries / Q000517:prevention & control*; D003764:Dental Materials / Q000737:chemistry*; D055119:Elastic Modulus; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D053761:Nanocomposites / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry
chemical_list: D001565:Benzoates; D002130:Calcium Phosphates; D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D011109:Polymethacrylic Acids; C519480:amorphous calcium phosphate; C080129:pyromellitic dianhydride glycerol dimethacrylate adduct; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; C074277:ethoxylated bis-phenol A dimethacrylate; D017438:Bisphenol A-Glycidyl Methacrylate
keywords: Calcium phosphate ion release; Calcium phosphate nanoparticles; Dental caries inhibition; Dental composite; Recharge; Remineralization