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. Me thods. Twenty general dental practitioners (GDPs) rated a total of 140 digital images (28 approximal surfaces at five different magnificatio ns, x3, x6, x12, x18 and x30) for caries on a 5-point confidence scale . The observations were compared with the state of the approximal surf aces on visual inspection. For each GDP the average response rate was calculated. Paired t-tests were used to compare the diagnostic respons e at the five different image magnifications. Results. The mean respon se rates obtained at x18 and x30 magnifications were significantly inf erior to those at the three smaller magnifications (p<0.007). Conclusi on. Digital image magnification has a significant influence on observe r performance in the detection of approximal caries, with an upper lim it beyond which diagnostic accuracy may be reduced. Further research i s needed to determine limits for various different diagnostic tasks so as to give GDPs guidelines on the appropriate magnifications to use.