Micro-CT versus SEM Backscatter imaging of early implant bone healing

Objectives: Three-dimensional analysis of bone growth around dental implants through microfocus computer tomography (micro-CT) allows non-destructive quantification of newly mineralized bone and correlates to measurements obtained using radiographic and SEM backscatter imaging (SBI). Methods: Six hounds had all mandibular premolars extracted and ridges allowed to heal for 3 months prior to implant placement. 60 titanium implants (3.5mm diameter x 8mm long) were placed in standardized circular defects (1mm peri-implant gap) created in the premolar region of the mandibles and allowed to heal for 2-8 weeks. The animals were sacrificed and the mandibles sectioned. Each specimen was scanned using micro-CT (ImTek MicroCAT II, Siemen, Knoxville TN) at 800kVp, 500uA using 2.0mm aluminum filter to acquire 1024 slices. Reconstruction slices were imported into Amira 4.1 (Mercury Computer Systems, Inc.) and areas of mineralization within the defect measured. A second set of measurements confined to the middle one-third of the defect were made to reduce the effects of streak artifact. Half of these specimens were embedded in plastic, sectioned, and imaged by SEM-BI. The amount of new bone growth in the defect area was quantified and compared to values obtained using micro-CT. Results: Bone geometry around the implant could be viewed in all dimensions at a resolution of 28.76ìm. The percent of bone fill within the middle one-third correlated strongly with the amount observed in the entire defect. (r=0.93, 0.02 < p < 0.05). The values obtained from the middle one-third of the defect also correlated strongly with the amount of new bone growth measured using SBI (r=0.90, p=0.001.) Conclusions: The results suggest that the effects of streak artifact did not greatly effect the measurements of bone fill as calculated using Micro-CT, and that measurements obtained from Micro-CT are reliable as compared to those from SEM-SBI. Supported by Astra Tech AB.