title: Morphometric assessment of enamel demineralisation from photographs.
abstract: OBJECTIVE
  To investigate the validity and reproducibility of a method of morphometric assessment of enamel demineralisation.
  
  
  METHODS
  An in vitro investigation was carried out on 22 human teeth. One investigator coated the crowns of the teeth with an acid-resistant varnish, leaving a small window on the buccal surface. This was incrementally occluded by varnish over a 14-day period, during which the teeth were placed in a demineralising gel at pH 4.5. After varnish removal, a second investigator blindly quantitated the demineralised area by three methods of examination; direct visual, microscopic and from photographs. The microscopic and photographic measurements were carried out using a morphometric assessment with a 121-dot array. Photographs and assessments were repeated after 1 week. The readings were analysed using the kappa statistic, the limits of agreement and the coefficient of repeatability.
  
  
  RESULTS
  Photographic assessments demonstrated excellent agreement for grid positioning (kappa > 0.81) and substantial agreement for reading reproducibility (kappa = 0.61-0.80). The coefficients of repeatability were found to be the same for repeat readings of the same slide and the repeated slides (5.0 mm2). They were higher for the microscopic technique (6.8 mm2) and for the direct visual technique (7.8 mm2). The limits of agreement are presented graphically.
  
  
  CONCLUSIONS
  The photographic technique used was a reproducible method of measuring artificial enamel demineralisation. Measurement from photographs was more reproducible than direct measurement with the naked eye. Subjectiveness of the index leads to most variation and more objective means of assessing enamel demineralisation need to be found.
authors.affiliation: Department of Clinical Dental Science, University of Liverpool School of Dentistry, UK.
authors.forename: P E
authors.initials: PE
authors.lastname: Benson
authors.forename: N
authors.initials: N
authors.lastname: Pender
authors.forename: S M
authors.initials: SM
authors.lastname: Higham
authors.forename: W M
authors.initials: WM
authors.lastname: Edgar
mesh_terms: D006801:Humans; D008853:Microscopy; D015588:Observer Variation; D010781:Photography; D015203:Reproducibility of Results; D017001:Tooth Demineralization / Q000473:pathology*