Avaliação comparativa das imagens por subtração obtidas por filme radiografico e sistemas digitais, no diagnostico de lesões de carie em esmalte

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The aim of the present study was to compare the diagnostic performance of digital subtraction images, acquired with InSight® film and three digital radiographic systems, CygnusRay MPS®, DenOptix® and DIGORA®, for the detection of approximal enamel caries-like lesions. In this investigation, 50 caries-free human third molars were randomly assigned to 5 groups: C " control teeth; 60 days; 75 days; 90 days; and 120 days" teeth that were immersed in a demineralizing solution for 60, 75, 90, and 120 days, respectively. The teeth were coated, leaving only a circular window of approximately 7 mm2 in one of the approximal surfaces, allowing contact with an acid solution 50% saturated in relation to the human dental enamel, in order to induce artificial enamel carious lesions. Standardized radiographs of the teeth were taken prior to and after each one of the demineralization periods. Linear and logarithmically enhanced subtraction images were then acquired. Three experienced and well-trained radiologists examined the reference and the final radiographs, by comparing the images, twice. The subtraction images were assessed by a fourth radiologist. At the end of the demineralization phase, the crowns were sectioned longitudinally through the center of the enamel test areas and submitted to Knoop microhardness profiling. Besides, demineralizing solutions of the four experimental groups were analyzed for phosphor and calcium concentrations. Kappa statistics was used to determine the reproducibility values for the diagnosis through conventional, digital and digitized radiographs; ROC analysis was performed to estimate the accuracy of the five radiographic image acquisition modalities. The areas under the ROC curves of linear and logarithmically enhanced subtraction images were also compared. DenOptix® system and the conventional radiography presented higher measures of performance. On the other hand, subtraction images obtained with InSight® film and the digital systems, CygnusRay MPS®, DenOptix® and DIGORA®, were diagnostically comparable. Accuracy values calculated for the subtraction images were greater than 92%; whereas, for the conventional, digital and digitized radiographs, the values ranged from 78,9 to 86,1%. Linear and logarithmically enhanced subtraction images performed significantly better in comparison to the original radiographs. In conclusion, the digital subtraction is a useful image processing tool and may potentially improve radiographic diagnosis of enamel approximal caries lesions.

ASSUNTO(S)

caries dentarias radiografia

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