Roles of bone scintigraphy and resonance frequency analysis in evaluating osseointegration of endosseous implant

The purpose of this study is to analyze the roles of two non-invasive techniques, bone scintigraphy and resonance frequency analysis (RFA), in the osseointegration assessment. Sixty implants with sandblasted/acid-etched (SA) or machined (MA) surface were placed into the distal femur condyles of 30 rabbits. At 1, 2, 4, 6, 8, and 12 weeks postsurgery, they were subjected to bone scintigraphy, digital radiographic examination, histological and histomorphometric analysis. RFA was performed on each implant both at the time of implant placement and animal sacrifice. The results showed that variation of Tc-99m-MDP uptake (bone scintigraphy value) coincided with that of new bone formation activity and accumulation of osteoblasts. Bone scintigraphy was more sensitive to the change of peri-implant bone than the digital radiographic examination. But it did not correlate with histomorphometric data and failed to detect the difference between SA and MA implants. It was found that RFA value increased with the bone-to-implant contact during the healing phase and correlated with the histomorphometric data. Moreover, RFA distinguished between the SA and MA implants. It is concluded, therefore, that bone scintigraphy may be a dynamic method on peri-implant bone healing, while RFA may be a reliable biomechanical technique that can monitor the osseointegration at macro level. We propose that the combination of these non-destructive techniques may facilitate the identification of the nature of osseointegration.