Accuracy of direct digital radiography in the study of the root canal type

To determine the accuracy of direct digital radiography (DDR) in the study of the root canal type. A sub aim was to assess intraexaminer and interexaminer agreement for this feature using DDR system.

100 recently extracted permanent maxillary first premolars from Chinese population were used. Standardized periapical DDR images were taken from a buccolingual and mesiodistal direction. Then the specimens were accessed, injected with dye, demineralized, dehydrated and finally were cleared. The DDR images were evaluated based on the root canal type by two independent trained post-graduate students (examiner A and B) twice at an interval of 2 weeks. The cleared teeth were examined under 5 x magnification using a dental operating microscope by another experienced endodontist, and the data of root canal type were collected.

The Kappa values for the agreement between the examiner A and the clearing technique were 0.3793 and 0.329, between the examiner B and the clearing technique were 0.2481 and 0.2184. While the Kappa values between the two observations of each examiner were 0.7704 and 0.7725, between the two examiners they were 0.537 and 0.4793, respectively.

The intraexaminer agreement was good, and the interexaminer agreement was moderate, but the agreement between either DDR examiner and the clearing technique was poor, indicating the limited value of DDR alone when studying root canal type.