Methodological aspects and quantitative adjuncts to computerized subtraction radiography

The methodology for the use of subtraction radiography in the study of human periodontal disease is described in detail to include: 1) design and fabrication of a system for taking standardized radiographs; 2) generation of interpretable subtraction images; 3) adjunctive, quantitative methods for analyses of digitized radiographic images; 4) reference standard for periodontally healthy individuals. Correct use of our system for taking standardized radiographs can provide a sufficient number of pairs of radiographs for the study of patients with severe periodontitis using subtraction radiography. Changes in bone mass observed on subtraction images can be quantified by measurement of their areas and their relationship to the alveolar crest.