Objectives: The ability of micro CT for quantitative analysis of peri-implant bone has never been addressed. This study aimed to establish and validate a method to use this technique for three-dimensional implant-bone profiling.

Methods: Two unthreaded, cylindrical implants with a dual acid-etched surface were placed into the femurs of an eight-week old male Sprague-Dawley rat. At week 2, the femurs were harvested and measured with a desktop micro CT, providing 8 µm isotropic resolution. In order to validate the micro CT outcome, ground histological sections and CT images at the corresponding cross-sections were compared for bone morphometry.

Results: The table shows average cortical and cancellous bone rates (bone volume/ total volume) obtained from three-dimensional micro CT images. The bone formation profile in the cancellous area was characterized as an increasing bone rate as approaching to implant surfaces.

Vicinity Level to Implant (µm)	0-24	24-48	48-72	72-96	96-120	120-144	144-240
Cortical Bone Rate (%)	87	90	88	83	82	82	78
Cancellous Bone Rate (%)	72	46	34	24	18	16	16

The correlation between histology and micro CT was significant for cortical bone (r=0.64; p<0.05) and cancellous bone (r=0.92; p<0.01) at distances from 24 to 240 µm. No significant correlation was found for the area from 0 to 24 µm (r=-0.24; p=0.57).

Conclusions: The results support the validity and usefulness of micro CT assessment as a rapid, non-invasive method for bone volume measurements around titanium implants. The data may need careful interpretation for the 24 µm wide area adjacent to the bone-implant interface.