title: The effects of noise reduction, sharpening, enhancement, and image magnification on diagnostic accuracy of a photostimulable phosphor system in the detection of non-cavitated approximal dental caries.
abstract: OBJECTIVE
  Contrast, sharpness, enhancement, and density can be changed in digital systems. The important question is to what extent the changes in these variables affect the accuracy of caries detection.
  
  
  METHODS
  Forty eight extracted human posterior teeth with healthy or proximal caries surfaces were imaged using a photostimulable phosphor (PSP) sensor. All original images were processed using a six-step method: (1) applying "Sharpening 2" and "Noise Reduction" processing options to the original images; (2) applying the "Magnification 1:3" option to the image obtained in the first step; (3) enhancing the original images by using the "Diagonal/" option; (4) reviewing the changes brought about by the third step of image processing and then, applying "Magnification 1:3"; (5) applying "Sharpening UM" to the original images; and (6) analyzing the changes brought about by the fifth step of image processing, and finally, applying "Magnification 1:3." Three observers evaluated the images. The tooth sections were evaluated histologically as the gold standard. The diagnostic accuracy of the observers was compared using a chi-squared test.
  
  
  RESULTS
  The accuracy levels irrespective of the image processing method ranged from weak (18.8%) to intermediate (54.2%), but the highest accuracy was achieved at the sixth image processing step. The overall diagnostic accuracy level showed a statistically significant difference (p=0.0001).
  
  
  CONCLUSIONS
  This study shows that the application of "Sharpening UM" along with the "Magnification 1:3" processing option improved the diagnostic accuracy and the observer agreement more effectively than the other processing procedures.
authors.affiliation: Department of Maxillofacial Radiology, Faculty of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Zahra Dalili
authors.initials: ZD
authors.lastname: Kajan
authors.affiliation: Department of Operative Dentistry, Faculty of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Tayefeh Davalloo
authors.affiliation: Department of Operative Dentistry, Faculty of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Mayam
authors.initials: M
authors.lastname: Tavangar
authors.affiliation: Faculty of Dentistry, Guilan University of Medical Sciences, Rasht, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Valizade
keywords: Dental Caries; Dental Digital Radiography; Image Enhancement