Matthias Wedel

Quality of individually calibrated customary printers for assessment of typical dental diagnoses on glossy paper prints: a multicenter pilot study.

OBJECTIVE The objective of this study was to compare dental radiographs printed on glossy paper from calibrated low-cost printers with monitor display. STUDY DESIGN Three typical intraoral radiographs were selected and a questionnaire was developed with questions assessing accuracy and subjective quality. A test pattern was designed for printer calibration. After calibration, radiographs were printed on glossy paper with 3 ink-jet and 2 thermo-sublimation printers. Sixteen raters evaluated the printed radiographs, 9 of them also on standardized viewing monitors. Subjective ratings were compared, and an ROC-analysis based on expert-consensus monitor readings was performed. RESULTS Low inter-rater reproducibility (mean Cohens Kappa monitor: 0.49; printers: 0.44), but high diagnostic accuracy was found for all printers (areas [Az] underneath the ROC curves: 0.725 to 0.884). The overlap between the 95% Az confidence intervals of the mean indicate no significant differences. CONCLUSION Our preliminary findings indicate that dental radiographs may be evaluated on glossy paper prints of calibrated customary printers.

Diagnostic yield of ink-jet prints from digital radiographs for the assessment of approximal carious lesions: ROC-analysis

AIMS 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. MATERIALS AND 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.