Impact of CBCT-Artefacts and Exposure Settings on Implant Measurement Accuracy

Objectives: To evaluate the effect of metallic artefact and kVp levels on the measurement accuracy of implants and osteotomy sites in two CBCT machines in-vitro.
Methods: A radiographically visible block was prepared. Five implants with progressive thread design (diameter: 3.5mm, length: 11mm) were placed perpendicular to the block. A groove was carved at 2mm apical to the implants to represent the mandibular canal. The block was scanned using two CBCT machines: Machine A (Kodak-9000, 70kVp, 7mA, 0.2mm voxel-size) and Machine B (I-CAT, 120kVp, 5mA, 0.3mm voxel-size). The exposure factors were set at the recommended factory presets. The implants were then removed; the osteotomy length was measured using a digital caliper at the center of the site and scanned in an identical manner. The scans were analyzed separately using iCATVision and CS3D-imaging software, with each software’s default window width and level settings. Measurements of the implant and osteotomy sites were done by two blinded examiners; mean values were recorded and subjected to statistical analysis using linear mixed model at 5% significance.
Results: No statistically significant difference for implant measurements was observed between the two machines independent of kVp-levels. However, significant difference was found in the osteotomy measurements of scans from Machine A, acquired at lower kVp-level than machine B (P< 0.0001), due to better visualization of remaining bone at the apical part of the osteotomy during implant removal (Table).
Conclusions: CBCT exposure parameters likely impact the effect of implant-caused metallic artefacts on the accuracy of measurements at surgical implant sites.