A controlled study on the diagnostic accuracy of panoramic and peri-apical radiography for detecting furcation involvement

BACKGROUND: The aims of this study were (1) to determine the accuracy, sensitivity, and specificity of panoramic and peri-apical radiographs in diagnosing furcation involvement, as well as (2) to evaluate the possible impact of clinical experience on these diagnostic parameters. METHODS: An existing radiographic dataset of periodontitis patients requiring implant surgery was retrospectively examined for furcation involvement. Criteria for inclusion were the presence of a CBCT, panoramic and peri-apical radiograph of the site of interest within a one-year time frame. All furcation sites were classified using the CBCT, which was considered as the gold standard, according to Hamp’s index (1975). Ten experienced examiners and 10 trainees were asked to assess furcation involvement for the same defects using only the corresponding panoramic and peri-apical radiographs. Absolute agreement, Cohen’s weighted kappa, sensitivity, specificity and ROC-curves were analyzed. RESULTS: The study sample included 60 furcation sites in 29 multi-rooted teeth from 17 patients. On average, 20/60 furcations were correctly classified according to the panoramic radiographs, corresponding to a weighted kappa score of 0.209, indicating slight agreement. Similarly, an average of 19/60 furcations were correctly classified according to the peri-apical radiographs, corresponding to a weighted kappa score of 0.211, also indicating slight agreement. No significant difference between panoramic and peri-apical radiography was found (P = 0.903). When recategorizing FI Grades into ‘no to limited FI’ (FI Grade 0 and I) and ‘advanced FI’ (FI Grade II and III), the panoramic and peri-apical radiography showed low sensitivity (0.558 and 0.441, respectively), yet high specificity (0.791 and 0.790, respectively) for identifying advanced FI. The ROC-curves for the panoramic and peri-apical radiographs were 0.79 and 0.69 respectively. No significant difference was found between experienced periodontists and trainees (P = 0.257 versus P = 0.880). CONCLUSION: Panoramic and peri-apical radiography are relevant tools in the diagnosis of FI and provide high specificity. Ideally, they are best used in combination with furcation probing, which shows high sensitivity. Furthermore, clinical experience does not seem to improve the accuracy of a radiological diagnosis of furcation sites. TRIAL REGISTRATION: Patient radiographic datasets were retrospectively analyzed.