title: A fractal dimensional approach to successful evaluation of apical healing.
abstract: OBJECTIVE
  To evaluate whether the initial healing of apical radiolucencies 1 year after root canal treatment could be quantitatively identified by the change in fractal dimension (FD) values for the eventually completely healed cases.
  
  
  METHODS
  Twenty-six patients with successful root canal treatment were recruited. All teeth were associated with complete healing either before or at 1 year following treatment (six of 26) or still undergoing healing at 1 year after treatment but completely healed thereafter (20 of 26). Two radiographs were selected for the same patient, one taken before treatment and the other taken 1 year after treatment. Eight regions of interests (ROIs) were selected from each radiograph, two as the experimental group located close to the infected root apex, two as the control group in the healthy bone and the other four in the healthy bone ensuring the image quality.
  
  
  RESULTS
  Based on the FD values of the four ROIs in the healthy bone, the two radiographs were confirmed to have been taken with similar projection angles and exposure. The FD values were shown to significantly increase (P = 0.006) and decrease (P = 0.000) around the root apex and the neighbouring region of the apical lesion, respectively.
  
  
  CONCLUSIONS
  Changes in fractal dimension values may serve as a necessary condition to quantitatively indicate the initial healing status 1 year after root canal treatment.
authors.affiliation: Department of Dentistry, National Taiwan University Hospital and, Graduate Institute of Clinical Dentistry, National Taiwan University Medical College, Taiwan.
authors.forename: C C
authors.initials: CC
authors.lastname: Huang
authors.forename: J C
authors.initials: JC
authors.lastname: Chen
authors.forename: Y C
authors.initials: YC
authors.lastname: Chang
authors.forename: J H
authors.initials: JH
authors.lastname: Jeng
authors.forename: C M
authors.initials: CM
authors.lastname: Chen
mesh_terms: D000539:Alveolar Process / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D017709:Fractals; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data; D008297:Male; D010485:Periapical Periodontitis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D016300:Radiography, Bitewing / Q000379:methods / Q000706:statistics & numerical data; D012390:Root Canal Therapy / Q000379:methods; D019227:Tooth Apex / Q000000981:diagnostic imaging / Q000503:physiopathology; D014945:Wound Healing / Q000502:physiology