Background: Radiographic measurements are often used as a substitute for direct clinical measurements requiring re-entry surgery for follow-up outcome studies.
Aims: (1) To assess the reliability of clinical and radiographic measurements of periodontal defects as compared to direct bone measurements during surgical procedures, and (2) to assess the associations between selected clinical and radiographic measurements of periodontal inter-proximal defects.
Methods: 57 inter-proximal periodontal defects were measured at baseline and at 12 months after surgical treatment. Direct measurements during surgery of the distance between the CEJ to the bottom of defects (ABL) were compared with probing to bone (PB), probing attachment level (PAL), and radiographic measurements.
Results: Probing to bone is an accurate measure to assess inter-proximal bone level as compared to ABL (mean difference: 0.1 mm) and that intra-oral standardized radiographs underestimate bone level and defect depth by approximately 1.4 mm. The interpretation of periodontal changes between baseline and 12 months after treatment by probing to bone, or PAL measurements, or from radiographic images yield almost identical results (mean difference< or =0.2 mm). For the assessments of changes over time using PB change as the standard, intra-class correlation (ICC) coefficients varied between 0.52 to 0.90. The best ICC coefficient was found for relative attachment level change assessed by the Florida probe (0.90), and with an ICC value of 0.61 for changes assessed from intra-oral radiographs. Two-way analysis of variance failed to demonstrate differences between sets of comparisons.
Conclusions: Both radiographic interpretations of changes over time, and measurements of attachment level changes are reliable in assessing the treatment outcome of inter-proximal intra-bony defects when compared to probing to bone changes as the standard method.