Materials and Methods: Six resin models with 3 implants in each were scanned with a spiral CT scanner (SP), an i-CAT cone beam scanner (iCAT) and a NewTom cone beam CT scanner (NT). Models were scanned twice with each scanner, providing three pairs of CT scans for each model for a total of 18 pairs. A computer-based implant-planning software was used to superimpose each pair. Reproducibility was evaluated by calculating implant deviations between each pair of CTs and compared among the three CT systems. Study variables included implant shoulder and apex vertical deviations, implant shoulder and apex horizontal deviations and angular deviations, expressed as mean±standard deviation. Comparison between the three CT systems was done using analysis of variance for the above study variables.
Results: Implant shoulder vertical deviations were 0.324±0.209mm, 0.279±0.185mm and 0.409±0.382mm and implant apex vertical deviations were0.324±0.21mm, 0.277±0.18 and 0.407±0.38mm for SP, iCAT and NT, respectively, p>0.05 for both variables. Implant shoulder horizontal deviations were 0.324 ±0.15mm, 0.343 ±0.175mm and 0.562 ±0.297 for SP, iCAT and NT, respectively, p<0.05. Apex horizontal deviations were 0.517±0.214mm, 0.529 ±0.219mm and 0.809±0.421mm for SP, iCAT and NT, respectively, p<0.05. The differences for both shoulder and apex horizontal deviations were significant for NT vs. SP and NT vs. iCAT. Angular deviations were 1.325±0.692°, 2.131±1.174° and 1.325 ±0.692 ° for SP, iCAT and NT, respectively, the differences being statistically significant for SP vs. iCAT.
Conclusions: Although there were significant differences between CT systems, all provided adequate reproducibility. SP, currently the gold standard in CT, was found to have the smallest deviations.