Journal of Dentistry
Volume 35, Issue 9 , Pages 737-743, September 2007

Characterisation of enamel white spot lesions using X-ray micro-tomography

  • Tiffany T.Y. Huang

      Affiliations

    • Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, NSW, Australia
    • Department of Orthodontics, Faculty of Dentistry, University of Sydney, NSW, Australia
    • ,
  • Allan S. Jones

      Affiliations

    • The Electron Microscope Unit, University of Sydney, NSW, Australia
    • ,
  • Li Hong He

      Affiliations

    • Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, NSW, Australia
    • ,
  • M. Ali Darendeliler

      Affiliations

    • Department of Orthodontics, Faculty of Dentistry, University of Sydney, NSW, Australia
    • ,
  • Michael V. Swain

      Affiliations

    • Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, NSW, Australia
    • Corresponding Author InformationCorresponding author. Tel.: +61 2 9351 8357; fax: +61 2 9351 8375.

Received 9 March 2007; received in revised form 25 May 2007; accepted 3 June 2007.

Abstract 

Objectives

The aim of this study was to characterise the mineral density (MD) of natural enamel white spot lesions (WSLs) using X-ray micro-tomography calibrated with different density hydroxyapatite phantoms.

Methods

Seven natural WSLs from four extracted non-carious premolar teeth were scanned at a voxel size of 7.6μm using a desktop X-ray micro-tomography system. Five hydroxyapatite phantoms (sintered pellets of hydroxyapatite powder) with densities ranging from 1.52 to 3.14g/cm3 were used as calibration standards for each scan. Three-dimensional image reconstruction enabled MD gradients throughout the lesion to be quantified using an MD calibration equation derived from hydroxyapatite phantoms. Background noise generated during the measurement of MD was reduced using a Gaussian filter.

Results

Gaussian filter reduced the signal-to-noise ratio (standard deviation) significantly while the basic MD information (average value) remained intact. The mineral gradients through the WSLs examined were compared and are discussed in terms of existing literature. The MD of sound enamel, apparent intact surface layer of WSL, and lowest level of WSL was found to be 2.65–2.89g/cm3, 2.23–2.58g/cm3 and 1.48–2.03g/cm3, respectively. Our MD results are comparable with other studies.

Conclusions

X-ray micro-tomography is a sensitive in vitro technique capable of characterising and quantifying MD of small non-cavitated WSLs. This method has a promising potential for future carious and quantitative remineralisation studies.

Keywords: Mineral density, Micro-computed tomography, White spot lesion, Enamel, Caries, Demineralisation, Hydroxyapatite

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PII: S0300-5712(07)00113-3

doi:10.1016/j.jdent.2007.06.001

Journal of Dentistry
Volume 35, Issue 9 , Pages 737-743, September 2007

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