DETECTION OF MINERAL LOSS IN APPROXIMAL ENAMEL BY SUBTRACTION RADIOGRAPHY

The purpose of the present study was to determine whether digital subt raction radiography will improve detectability of small, mechanically prepared defects within dental enamel. Lesions with an extent of 1 mm in vertical direction and representing 5% to 10% mineral loss in the d irection of the x-ray beam were prepared in eight extracted molars. Ra diographs of teeth with defects were subtracted from radiographs taken before the lesions were prepared. Seven observers evaluated the image s using a five-point confidence rating scale (receiver operating chara cteristic technique). Examination of the original radiographs showed i ncreasing accuracy of radiographic interpretation with increasing mine ral loss as judged from the areas beneath the receiver operating chara cteristic curves. The same observation was made using subtraction imag es with and without contrast enhancement. There was no indication that subtracted images provided better diagnostic validity than the origin al radiographs. In conclusion, subtraction images do not seem to impro ve the diagnosis of well-defined lesions within dental enamel.