Imaging of periimplant bone levels of implants with buccal bone defects

The aim of the present study was to use four different methods to evaluate three radiographic techniques for their accuracy in assessing the marginal periimplant bone levels at implants with buccal bone defects in an experimental setting. Twenty-four implants were placed in the mandibles of six adult beagle dogs with substantial buccal bone defects, which were augmented by bone particles with and without resorbable membranes. After healing for 5 months, (1) periapical radiographs, (2, 3) reformatted images in (2) sagittal and (3) coronal planes from axial computer tomography (CT) scans and (4) direct magnification images (DIMA) were made and compared with histometric analysis of bone levels. Two values were used for comparison: (i) the lingual bone level and (ii) the true bone level calculated as a mean value from the lingual and the buccal bone levels of all histologic sections of each implant. Metric evaluation of periapical radiographs, sagittal reformation of CT scans and DIMA showed that the results were close to the histometrically assessed lingual bone level, while the true bone level was significantly lower and not reflected by any of the imaging modalities. Coronal reformation showed that there was significant overestimation of the lingual and underestimation of the buccal bone level when compared with histometric values. It is concluded that assessment of bone level and bone regeneration in implants with buccal bone defects remains problematic, and data from periapical radiograms tend considerably to overestimate the bone anchorage of these implants.