title: Technical factors in fractal analysis of periapical radiographs.
abstract: OBJECTIVE
  Fractal analysis quantifies complex geometric structures by generating a fractal dimension, which can measure trabecular bone density. The use of non-standardized radiographic techniques potentially limits the reliability of fractal analysis. The objective of this study was to determine how variations in radiographic technique affect fractal dimension.
  
  
  METHODS
  Periapical radiographs of maxillary incisors taken on eight dry human skulls at varying angulation, tube potential and impulse settings were subjected to Fourier transform fractal analysis.
  
  
  RESULTS
  A significant (p < 0.05) difference in fractal dimension, ranging from 2.5 to 2.9, was found between the skulls, potentially reflecting variations in bone trabeculation. However, variations in angulation, tube potential or impulse did not have a statistically significant effect (p > 0.05) on fractal dimension, with the standard deviation of the fractal dimension ranging from +/- 0.005 to +/- 0.062 at various radiographic machine settings.
  
  
  CONCLUSIONS
  This study indicates that non-standardized periapical radiographs may provide a reliable method for determining fractal dimensions, which could be useful in analysing changes in alveolar bone density in various bone disorders.
authors.affiliation: Department of Growth and Development, University of California, San Francisco, USA.
authors.forename: L
authors.initials: L
authors.lastname: Jolley
authors.forename: S
authors.initials: S
authors.lastname: Majumdar
authors.forename: S
authors.initials: S
authors.lastname: Kapila
mesh_terms: D000539:Alveolar Process / Q000000981:diagnostic imaging; D015519:Bone Density / Q000502:physiology; D005583:Fourier Analysis; D017709:Fractals; D006801:Humans; D007180:Incisor / Q000000981:diagnostic imaging*; D008437:Maxilla / Q000000981:diagnostic imaging*; D010486:Periapical Tissue / Q000000981:diagnostic imaging*; D016300:Radiography, Bitewing / Q000379:methods / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D013674:Technology, Dental