Background and Objective:  A report describing the software Dental Image Analyzer (DIA) was published in this journal in 2009. A new function – measurement of the periodontal intrabony defect angle – was added to the software in 2010. The purpose of this study was to investigate whether measurements of the radiographic intrabony defect angle using digital radiographs and the newly developed DIA tool were comparable with measurements obtained using the conventional protractor method.

Material and Methods:  The baseline radiographic defect angle of intrabony defects was measured conventionally, using a protractor, in 60 selected teeth from 47 patients and then digitally using the newly developed DIA tool. The measurements were made independently by four experienced dentists. The radiographic defect angle of intrabony defects was measured after the three anatomical landmarks were identified, namely the cemento–enamel junction, the top of the crest and the bottom of the defect.

Results:  Both methods showed a high interexaminer reliability for measurements of the radiographic defect angle of intrabony defects (intraclass correlation coefficient > 0.97). Moreover, both methods showed high reliability (intraclass correlation coefficient > 0.96). On the other hand, the new DIA tool, compared with the conventional method, exhibited high sensitivity (0.92) and high specificity (0.91) in selecting defects of ≥ 37° or < 37°. Analysis of the time taken for measurements revealed significant differences between the two methods, with the protractor method being more time consuming.

Conclusions:  This study provided evidence for the lack of a significant difference between the conventional method and the DIA tool for radiographic measurement of intrabony defects. However, digital analysis was significantly faster.