title: Effect of ambient light and bit depth of digital radiograph on observer performance in determination of endodontic file positioning.
abstract: OBJECTIVE
  To examine the effects of the luminance and bit depth of digital image on observer performance for determination of endodontic file positioning.
  
  
  METHODS
  Using extracted premolar teeth, no. 08 K-file was placed into the canal and positioned so that the tip was either flush or 1 mm short of the radiologic root apex. The samples were imaged with both conventional and digital radiographs at 8 and 12 bits. Eleven observers read the images under dark and bright condition, and receiver operating characteristics analysis was performed. Additionally, the interpreting time was measured.
  
  
  RESULTS
  The 12-bit images showed similar observer performance compared with conventional images, and better than the 8-bit images. The interpretation time for bright condition and 8-bit images was longer than for dark condition and 12-bit images.
  
  
  CONCLUSIONS
  Twelve-bit digital images were preferred to 8-bit for accurate determination of endodontic file position.
authors.affiliation: Department of Oral Radiology, BK21, and Dental Research Institute, College of Dentistry, Seoul National University, Seoul, South Korea.
authors.forename: Min-Suk
authors.initials: MS
authors.lastname: Heo
authors.forename: Dong-Hun
authors.initials: DH
authors.lastname: Han
authors.forename: Byung-Mo
authors.initials: BM
authors.lastname: An
authors.forename: Kyung-Hoe
authors.initials: KH
authors.lastname: Huh
authors.forename: Won-Jin
authors.initials: WJ
authors.lastname: Yi
authors.forename: Sam-Sun
authors.initials: SS
authors.lastname: Lee
authors.forename: Soon-Chul
authors.initials: SC
authors.lastname: Choi
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D006801:Humans; D008029:Lighting; D015588:Observer Variation; D009811:Odontometry; D012372:ROC Curve; D019252:Radiography, Dental, Digital; D011873:Radiology Information Systems; D015203:Reproducibility of Results; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods