EFFECT OF IMAGE MAGNIFICATION OF DIGITIZED BITEWING RADIOGRAPHS ON APPROXIMAL CARIES DETECTION - AN IN-VITRO STUDY

Objective. To evaluate whether or not image magnification of digitized bitewing radiographs had an effect on approximal caries detection. Methods. Twenty general dental practitioners (GDPs) rated a total of 140 digital images (28 approximal surfaces at five different magnifications, x3, x6, x12, x18 and x30) for caries on a 5-point confidence scale. The observations were compared with the state of the approximal surfaces on visual inspection. For each GDP the average response rate was calculated. Paired t-tests were used to compare the diagnostic response at the five different image magnifications. Results. The mean response rates obtained at x18 and x30 magnifications were significantly inferior to those at the three smaller magnifications (p<0.007). Conclusion. Digital image magnification has a significant influence on observer performance in the detection of approximal caries, with an upper limit beyond which diagnostic accuracy may be reduced. Further research is needed to determine limits for various different diagnostic tasks so as to give GDPs guidelines on the appropriate magnifications to use.