Three-dimensional bone-implant integration profiling using micro-computed tomography.

PURPOSE The capability of micro-computed tomography (microCT) for quantitative analysis of peri-implant bone has not been previously addressed. This study aimed to establish and validate a method to use this technique for 3-dimensional bone-implant integration profiling. MATERIALS AND METHODS Unthreaded cylindric implants with a dual acid-etched surface were placed into the right femurs of 7 Sprague-Dawley rats. Two weeks postimplantation, the femurs were harvested and measured with a desktop micro-tomographic scanner with an isotropic resolution of 8 microm. To validate the microCT outcome, ground histologic sections and corresponding CT slices were compared with respect to bone morphometry. RESULTS Bone-implant integration profiles assessed by microCT revealed that the percentage of cancellous bone gradually increased with proximity to the implant surface, while the percentage of cortical bone was not affected by proximity to the implant. Using the optimized segmentation threshold, the bone configuration in the microCT images corresponded to that observed in the histologic sections. The correlation between microCT and histology was significant for cortical (r = 0.65; P < .05) and cancellous bone (r = 0.92; P < .05) at distances of 24 to 240 microm from the implant surface, but no significant correlation was found for the area from 0 to 24 microm from the surface. DISCUSSION AND CONCLUSION The results support the usefulness of microCT assessment as a rapid, nondestructive method for 3-dimensional bone ratio measurements around implants, which may provide new perspectives for osseointegration research. Further study is necessary, however, to address the inherent metallic halation artifact, which potentially confounds peri-implant bone assessment.