title: A comparative study of the bioactivity of three materials for dental applications.
abstract: OBJECTIVE
  The aim of this work was to investigate the in vitro bioactivity of two different experimental dental luting cement formulations based on calcium aluminate (CA) in comparison with glass ionomer cement (GIC). One of the CA-based formulations was a hybrid between CA and GIC.
  
  
  METHODS
  Samples were submerged in phosphate buffered saline and stored at 37 degrees C for four periods of time: 1 h, 1 day, 7 days and 4 weeks. After storage the samples were analyzed in order to investigate if a surface layer of hydroxyapatite had formed. The analysis techniques used included grazing incidence X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy.
  
  
  RESULTS
  Both the CA-containing formulations were found to be bioactive. The highest degree of bioactivity was found on the sample with only CA as active substance. A relatively thick and totally covering layer was already formed after 24 h. On the hybrid material hydroxyapatite was found after 7 days. The GIC showed no bioactivity during the test period.
  
  
  CONCLUSIONS
  The utilization of a bioactive material for tooth restorations will give an opportunity for remineralization and a natural and durable seal of the tooth-material interface. Materials based on CA exhibit bioactivity.
authors.affiliation: Department of Materials Science, Angstrom Laboratory, Uppsala University, Uppsala, Sweden. jesper.loof@doxa.se
authors.forename: Jesper
authors.initials: J
authors.lastname: Lööf
authors.forename: Fredrik
authors.initials: F
authors.lastname: Svahn
authors.forename: Tobias
authors.initials: T
authors.lastname: Jarmar
authors.forename: Håkan
authors.initials: H
authors.lastname: Engqvist
authors.forename: Cornelis H
authors.initials: CH
authors.lastname: Pameijer
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D002021:Buffers; D017610:Calcium Compounds / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry; D004577:Electron Probe Microanalysis; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D010710:Phosphates / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D017607:Aluminum Compounds; D001672:Biocompatible Materials; D002021:Buffers; D017610:Calcium Compounds; D003738:Dental Cements; D005899:Glass Ionomer Cements; D010710:Phosphates; C035219:calcium aluminate; D012965:Sodium Chloride; D017886:Durapatite