title: Logistic regression equation to screen for vertical root fractures using periapical radiographs.
abstract: OBJECTIVE
  To develop a predictive equation to screen for vertical root fractures (VRFs) by numerically evaluating the shapes of radiolucent areas on the periapical radiographs of endodontically treated maxillary incisors and premolars.
  
  
  METHODS
  41 pre-operative periapical radiographs of maxillary incisors and premolars with radiolucent areas at root apices were used. Out of 41 teeth, 18 had a fractured root (VRF group) and 23 had a non-fractured root (non-VRF group). The periapical radiolucent area of each tooth was traced out by six examiners on a personal computer and two indices, "Complexity" and "Radial SD", were measured. For each index, the difference between the VRF and non-VRF groups and the interexaminer differences were analysed with two-way ANOVA at 5% significance level. Multiple logistic regression analysis was used to develop a predictive equation and the probability of VRF in all samples was calculated. A receiver operating characteristic (ROC) curve was constructed to select the optimal cut-point. Each sample was predicted as "VRF" or "non-VRF" with this cut-point.
  
  
  RESULTS
  For both "Complexity" and "Radial SD", the VRF group showed significantly greater values than the non-VRF group (P<0.05). With a cut-point derived from the ROC curve, sensitivity, specificity and efficiency of VRF were 0.68, 0.80 and 0.75, respectively.
  
  
  CONCLUSIONS
  VRF teeth have more complicated radiolucent areas compared with non-VRF teeth. By evaluating the shapes of radiolucent areas, a logistic regression equation to screen for VRF was calculated and this equation could contribute to the diagnosis of VRF.
authors.affiliation: Pulp Biology and Endodontics, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. y.kawamura.endo@tmd.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Kawamura-Hagiya
authors.forename: T
authors.initials: T
authors.lastname: Yoshioka
authors.forename: H
authors.initials: H
authors.lastname: Suda
mesh_terms: D004812:Epidemiologic Methods; D006801:Humans; D011859:Radiography; D014082:Tooth Fractures / Q000000981:diagnostic imaging*; D014092:Tooth Root / Q000000981:diagnostic imaging / Q000293:injuries*; D019553:Tooth, Nonvital / Q000000981:diagnostic imaging*