title: The efficacy of the reverse contrast mode in digital radiography for the detection of proximal dentinal caries.
abstract: OBJECTIVE
  This study evaluated the diagnostic accuracy of the reverse contrast mode in intraoral digital radiography for the detection of proximal dentinal caries, in comparison with the original digital radiographs.
  
  
  METHODS
  Eighty extracted premolars with no clinically apparent caries were selected, and digital radiographs of them were taken separately in standard conditions. Four observers examined the original radiographs and the same radiographs in the reverse contrast mode with the goal of identifying proximal dentinal caries. Microscopic sections 5 µm in thickness were prepared from the teeth in the mesiodistal direction. Four slides prepared from each sample used as the diagnostic gold standard. The data were analyzed using SPSS (α=0.05).
  
  
  RESULTS
  Our results showed that the original radiographs in order to identify proximal dentinal caries had the following values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, respectively: 72.5%, 90%, 87.2%, 76.5%, and 80.9%. For the reverse contrast mode, however, the corresponding values were 63.1%, 89.4%, 87.1%, 73.5%, and 78.8%, respectively. The sensitivity of original digital radiograph for detecting proximal dentinal caries was significantly higher than that of reverse contrast mode (p<0.05). However, no statistically significant differences were found regarding specificity, positive predictive value, negative predictive value, or accuracy (p>0.05).
  
  
  CONCLUSIONS
  The sensitivity of the original digital radiograph for detecting proximal dentinal caries was significantly higher than that of the reversed contrast images. However, no statistically significant differences were found between these techniques regarding specificity, positive predictive value, negative predictive value, or accuracy.
authors.affiliation: Department of Endodontics, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Shimasadat
authors.initials: S
authors.lastname: Miri
authors.affiliation: Department of Oral and Maxillofacial Radiology, School of Dentistry, Islamic Azad University, Tehran, Iran.
authors.forename: Sandra
authors.initials: S
authors.lastname: Mehralizadeh
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry, Islamic Azad University, Tehran, Iran.
authors.forename: Donya
authors.initials: D
authors.lastname: Sadri
authors.affiliation: Department of Research, School of Dentistry, Isfahan Branch, Islamic Azad University, Isfahan, Iran.
authors.forename: Mahmood Reza Kalantar
authors.initials: MR
authors.lastname: Motamedi
authors.affiliation: Dental Students Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Parisa
authors.initials: P
authors.lastname: Soltani
keywords: Dental Caries; Image Enhancement; Image Processing, Computer-Assisted; Radiography, Dental, Digital