VALIDITY OF RADIOGRAPHIC MEASUREMENT OF INTERPROXIMAL BONE LOSS

The aim of the present study was to compare radiographic assessment of interproximal bone loss using a loupe with a 0.1 mm calibrated grid a nd a computer-assisted analysis system (LMSRT). In 35 patients sufferi ng from untreated advanced periodontal disease, 62 standardized radiog raphs were taken presurgically. The horizontal and vertical angulation difference of the central beam from the orthoradial projection was ca lculated for each radiograph. At the time of surgery, for 115 interpro ximal defects, the distances from the cementoenamel junction (CEJ) to alveolar crest (AC), and CEI to bottom of the bony defect (ED) were me asured. In all radiographs, the linear distances CEJ to AC, and CEJ to BD were assessed using a loupe and LMSRT. Comparison between radiogra phic and intrasurgical assessments was performed using paired t-tests. A stepwise multiple linear regression analysis was used to evaluate f actors that influence the discrepancy between radiographic and intrasu rgical measurements. Both analyzing techniques underestimated interpro ximal bone loss as compared with intrasurgical measurements (CEJ-AC: l oupe: 0.86 +/- 1.84 mm [p < 0.001]; LMSRT: 0.58 +/- 1.86 mm [p < 0.005 ]; CEJ-BD: loupe: 1.22 +/- 2.33 mm [p < 0.001]; LMSRT: 0.80 +/- 2.09 m m [p < 0.001]). LMSRT underestimated interproximal bone loss significa ntly less than the loupe (p < 0.001). The difference between LMSRT and intrasurgical assessments was modulated by the factors of vertical an d horizontal angulation difference and defect depth (p < 0.1). Orthora dial projection reduced underestimation of radiographic assessment of bone loss. LMSRT underestimated interproximal bone loss to a lesser ex tent than conventional evaluation by loupe.