title: In vitro remineralization of enamel by polymeric amorphous calcium phosphate composite: quantitative microradiographic study.
abstract: OBJECTIVE
  This study explores the efficacy of an experimental orthodontic amorphous calcium phosphate (ACP) composite to remineralize in vitro subsurface enamel lesions microradiographically similar to those seen in early caries.
  
  
  METHODS
  Lesions were artificially created in extracted human molars. Single tooth sections a minimum of 120microm thick were cut and individually placed in holders exposing only the carious enamel surface. The exposed surfaces were either left untreated (control) or coated with a 1mm thick layer of the experimental ACP composite (mass fraction 40% zirconia-hybridized ACP and 60% photo-activated resin), or a commercial fluoride-releasing orthodontic cement. The composite-coated sections were then photo-cured and microradiographic images were taken of all three groups of specimens before the treatment. Specimens were then cyclically immersed in demineralizing and remineralizing solutions for 1 month at 37 degrees C to simulate the pH changes occurring in the oral environment. Microradiographs of all specimens were taken before and after treatment.
  
  
  RESULTS
  Quantitative digital image analysis of matched areas from the contact microradiographs taken before and after treatment indicated higher mineral recovery with ACP composites compared to the commercial orthodontic F-releasing cement (14.4% vs. 4.3%, respectively), while the control specimens showed an average of 55.4% further demineralization.
  
  
  CONCLUSIONS
  Experimental ACP composite efficiently established mineral ion transfer throughout the body of the lesions and restored the mineral lost due to acid attack. It can be considered a useful adjuvant for the control of caries in orthodontic applications.
authors.affiliation: Paffenbarger Research Center, American Dental Association Foundation, National Institute of Standards and Technology, 100 Bureau Drive Stop 8546, Gaithersburg, MD 20899-8546, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Langhorst
authors.forename: J N R
authors.initials: JN
authors.lastname: O'Donnell
authors.forename: D
authors.initials: D
authors.lastname: Skrtic
mesh_terms: D002118:Calcium / Q000032:analysis; D002130:Calcium Phosphates / Q000737:chemistry / Q000494:pharmacology*; D002327:Cariostatic Agents / Q000494:pharmacology*; D003731:Dental Caries / Q000503:physiopathology*; D003743:Dental Enamel / Q000187:drug effects*; D005459:Fluorides / Q000032:analysis / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008852:Microradiography; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000737:chemistry; D010710:Phosphates / Q000032:analysis; D010795:Phthalic Acids / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry / Q000494:pharmacology*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013997:Time Factors; D014089:Tooth Remineralization / Q000379:methods*; D014961:X-Ray Diffraction; D015040:Zirconium / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D002130:Calcium Phosphates; D002327:Cariostatic Agents; D008689:Methacrylates; D008903:Minerals; D010710:Phosphates; D010795:Phthalic Acids; D011109:Polymethacrylic Acids; D019279:Resin Cements; C519480:amorphous calcium phosphate; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; C074277:ethoxylated bis-phenol A dimethacrylate; C005044:hydroxyethyl methacrylate; C032279:phthalic acid; D015040:Zirconium; D005459:Fluorides; C028541:zirconium oxide; D002118:Calcium