title: Fractal dimension evaluation of cone beam computed tomography in patients with bisphosphonate-associated osteonecrosis.
abstract: OBJECTIVE
  The aim of this study was to (1) evaluate the fractal dimension (FD) in regions of the mandible on cone beam CT (CBCT) images of patients with bisphosphonate-associated osteonecrosis of the jaws (BP-ONJ) and (2) to select the most suitable region of interest (ROI) for further study on detection of bone alterations associated with bisphosphonates.
  
  
  METHODS
  CBCT images of patients with BP-ONJ were included with matched controls. Values of FD were compared between groups. Selected ROIs were: ROI-1 - below the mandibular foramen; ROI-2 - above the mandibular foramen; ROI-3 - anterior to the mental foramen; ROI-4 - above the mandibular canal. The area of bone exposure was included as ROI-5. The results were analysed using generalized estimating equations and conditional logistic regression.
  
  
  RESULTS
  There were 36 patients (67% female) with a mean age of 60.7 years. The mean FDs were: ROI-1 - 1.678 for controls and 1.673 for patients (P  =  0.81); ROI-2 - 1.657 for controls and 1.653 for patients (P  =  0.78); ROI-3 - 1.661 for controls and 1.684 for patients (P  =  0.17); and ROI-4 - 1.670 for controls and 1.698 for patients (P  =  0.03). The value of the FD in the area of exposed bone was the highest (1.729). The odds of being a BP-ONJ patient vs being a control was six times as high for individuals with a higher FD score at ROI-4, although the confidence interval was quite wide owing to the small sample size.
  
  
  CONCLUSIONS
  In this preliminary study, BP-ONJ patients had higher FD values than controls at regions close to the alveolar process. The results suggest that FD is a promising tool for detection of bone alterations associated with BP-ONJ.
authors: Department of Oral Medicine, University of Washington, Seattle, WA, USA. sandratorres@ufrj.br
authors: S R
authors: SR
authors: Torres
authors: C S K
authors: CS
authors: Chen
authors: B G
authors: BG
authors: Leroux
authors: P P
authors: PP
authors: Lee
authors: L G
authors: LG
authors: Hollender
authors: M M
authors: MM
authors: Schubert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050071:Bone Density Conservation Agents / Q000009:adverse effects*; D016022:Case-Control Studies; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D004164:Diphosphonates / Q000009:adverse effects*; D005260:Female; D017709:Fractals; D006801:Humans; D016015:Logistic Models; D008297:Male; D008336:Mandibular Diseases / Q000139:chemically induced* / Q000000981:diagnostic imaging*; D008875:Middle Aged; D010020:Osteonecrosis / Q000139:chemically induced* / Q000000981:diagnostic imaging*; D010865:Pilot Projects; D012044:Regression Analysis; D012189:Retrospective Studies; D016037:Single-Blind Method
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates