Detection and measurement of approximal radiolucencies by computer-aided image analysis

Serial standardized bitewing radiography permits monitoring of the development of approximal carious lesions. A quantitative method using image-analysis techniques was developed. Only certain types of hardware proved capable of processing this complex image adequately. A computer-aided, software-driven, TV-based system incorporating an image memory, recursive filtration, and 256 gray-level resolution, which can both detect and measure approximal enamel radiolucencies produced by natural carious lesions, has been developed. The radiolucent boundary is delineated, displayed, and plotted to scale. For the first time, objective values for depth, area, width, perimeter, and "degree of radiolucency" can be automatically derived. Currently the system is seen as a tool in caries research; in the future such systems may have wider applications.