Comparison of observer reliability in assessing alveolar bone changes from color-coded with subtraction radiographs.

OBJECTIVES To assess intra- and interobserver agreement on marginal changes in periodontal bone from color-coded compared with subtraction radiographs. METHODS Sequential radiographs from patients undergoing periodontal treatment were acquired using direct digital intra-oral radiography. Fifty-one pairs of color-coded and subtraction radiographs were produced and evaluated twice by six dentists for changes in marginal bone. Intra- and interobserver agreement were calculated. RESULTS Intra-observer agreement was significantly higher for the color-coded radiographs (P < 0.05). Interobserver agreement was significantly higher for color-coded radiographs at the second (P < 0.001) but not the first (P = 0.34) evaluation. CONCLUSIONS Color coding of radiographic differences by means of image addition may be a feasible alternative to the subtraction technique for evaluating periodontal bone changes.