Reliability of digital radiography of interproximal dental caries.
OBJECTIVE
To compare the effects of different image processing modes (filters) on the reproducibility and validity of the assessment of interproximal carious lesions viewed in digitized radiographic images.


METHODS
Variables studied were film type, exposure time, and tissue scatter radiation. Images were assessed in relation to film type, exposure time and tissue scatter. Standardized radiographs of 50 extracted teeth were obtained and 44 areas of interproximal caries were detected. Six radiographs were obtained of each tooth and digitized using FRIACOM software. Four were made using D-type film with and without soft tissue scatter equivalent at normal exposure time (0.32 seconds) and underexposed (0.16 seconds). Two were made using E-type film with TSE normal (0.16 seconds) and underexposed (0.08 seconds). On each of the 300 radiographs, the central depth (CD) of each carious lesion was measured at 18x magnification both on the unchanged radiographic image and after use of two different filters. All measurements were repeated after 1 week to estimate reproducibility.


RESULTS
Histometric CD assessments provided a gold standard for comparison with the radiographic measurements (validity). Whereas reproducibility was not influenced by one of the filters, filter "structure" improved the overall validity of CD measurements. In this study, digital manipulations of radiographic images resulted in statistically significant improvement of the validity of CD measurements.
Sanden
Etje
E
Section of Periodontology, Department of Operative Dentistry and Periodontology, Ruprecht-Karls-University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.
Koob
Andreas
A
Hassfeld
Stefan
S
Staehle
Hans Jörg
HJ
Eickholz
Peter
P
D003731:Dental Caries / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D011856:Radiographic Image Enhancement; D019252:Radiography, Dental, Digital / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D013997:Time Factors; D014962:X-Ray Film / Q000145:classification