title: Effect of Contrast Inversion Enhancement on the Accuracy of Endodontic File Length Determination in Digital Radiography.
abstract: OBJECTIVE
  The aim of this ex vivo study was to evaluate the accuracy of endodontic file length measurement on digital periapical radiographs after application of contrast inversion digital enhancement.
  
  
  METHODS
  Forty single-rooted single-canal mature permanent human teeth with canals measuring 20-24 mm in length were used in this study. ISO #08 K-files were placed in the root canals of the teeth. The file lengths were measured with a digital caliper as the gold standard. Standard periapical digital images were obtained with the Digora storage phosphor plates and Digora Optime scanner as the original images. The contrast inversion option of Scanora software program version 5.1 was used to produce enhanced images. Three radiologists and three endodontists measured file lengths on the original and enhanced images. The measurements were compared using repeated measures ANOVA and Bonferroni tests (α=0.05).
  
  
  RESULTS
  There were significant differences between the measurement accuracy of the original and enhanced images (p<0.05). The enhanced images exhibited longer measurements compared to the original images. However, the two sets of digital radiographs provided significantly longer measurements compared to the gold standard (p<0.05).
  
  
  CONCLUSIONS
  The contrast inversion tool of Scanora software program decreases measurement accuracy of the length of small endodontic files on digital periapical radiographs. It is suggested that contrast inversion should not be used in determining the lengths of small endodontic files.
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Radiology, School of Dentistry, Physiology Research Center, Ahvaz Jundishapur University of Medical Sciences , Ahvaz, Iran .
authors.forename: Nastaran
authors.initials: N
authors.lastname: Farhadi
authors.affiliation: Assistant Professor, Department of Endodontics, School of Dentistry, Isfahan University of Medical Sciences , Isfahan, Iran .
authors.forename: Ali
authors.initials: A
authors.lastname: Shokraneh
authors.affiliation: Associate Professor, Department of Oral and Maxillofacial Radiology, School of Dentistry, Torabinejad Dental Research Center, Dental Implants Research Center, Isfahan University of Medical Sciences , Isfahan, Iran .
authors.forename: Mojdeh
authors.initials: M
authors.lastname: Mehdizadeh
keywords: Image enhancement; Root canals; Scanora software