title: Diagnostic yield of ink-jet prints from digital radiographs for the assessment of approximal carious lesions: ROC-analysis.
abstract: OBJECTIVE
  To investigate the diagnostic quality of different quality, individually calibrated ink-jet printers for the very challenging dental radiographic task of approximal carious lesion detection.
  
  
  METHODS
  A test-pattern evaluating resolution, contrast and homogeneity of the ink-jet prints was developed. 50 standardized dental radiographs each showing two neighbouring teeth in natural contact were printed on glossy paper with calibrated, randomly selected ink-jet printers (Canon S520 and iP4500, Epson Stylus Photo R2400). Printing size equalled the viewing size on a 17″ cathode-ray-tube monitor daily quality-tested according to German regulations. The true caries status was determined from serial sectioning and microscopic evaluation. 16 experienced observers evaluated the radiographs on a five-point confidence scale on all prints plus the viewing monitor with respect to the visibility of a carious lesion. A non-parametric Receiver-Operating Characteristics (ROC-) analysis was performed explicitly designed for the evaluation of readings stemming from identical samples but different modality. Significant differences are expressed by a critical ratio z exceeding ±2. Diagnostic accuracy was determined by the area (Az) underneath the ROC-curves.
  
  
  RESULTS
  Average Az-values ranged between 0.62 (S520 and R2400) and 0.64 (monitor, iP4500), with no significant difference between modalities (P=0.172). Neither significant (range mean z: -0.40 (S520) and -0.11 (iP4500)) nor clinically relevant differences were found between printers and viewing monitor.
  
  
  CONCLUSIONS
  Our results for a challenging task in dental radiography indicate that calibrated, off-the-shelf ink-jet printers are able to reproduce (dental) radiographs at quality levels sufficient for radiographic diagnosis in a typical dental working environment.
authors.affiliation: Poliklinik für Zahnärztliche Chirurgie, University Medical Center of the Johannes Gutenberg-University, Augustusplatz 2, D-55131 Mainz, Germany. rschulze@mail.uni-mainz.de
authors.forename: Ralf K W
authors.initials: RK
authors.lastname: Schulze
authors.forename: Stefanie
authors.initials: S
authors.lastname: Grimm
authors.forename: Dirk
authors.initials: D
authors.lastname: Schulze
authors.forename: Kai
authors.initials: K
authors.lastname: Voss
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Keller
authors.forename: Matthias
authors.initials: M
authors.lastname: Wedel
mesh_terms: D016287:Computer Peripherals; D003731:Dental Caries / Q000000981:diagnostic imaging*; D006801:Humans; D007281:Ink; D010209:Paper; D011327:Printing / Q000295:instrumentation*; D012372:ROC Curve; D019252:Radiography, Dental, Digital; D015203:Reproducibility of Results