The aim of this study was to develop a computerized measurement system for analysis of unstandardized serial radiographic images. A new approach for estimating the error associated with the determination of alveolar crest loss is described. The study shows that a difference of 0.87 mm in cemento-enamel junction-crest measurement between unstandardized serial radiographs taken within accepted clinic routine is required for a significant loss in crestal bone height. The ability to detect with significance a difference of less than 1 mm in crestal bone height makes the appropriate use of traditional bite-wing radiographs a useful diagnostic tool for the assessment of periodontal maintenance.