Influence of zirconia crowns artifacts on cone beam computed tomography and image superimposition for digital planning and guided surgery

Abstract

ABSTRACT

Aim & Hypothesis: The purpose of this in vitro study is to evaluate the effect of zirconia crowns restorations on superimposition process and guided surgery Materials & Methods: Four stone casts generated four groups: a Control Group (CG) with no crowns and three Test Groups with 4 (TG4), 7 (TG7) and 13 (TG13) zirconia crowns. A total of 40 CBCT scans were taken for the four groups (10 CG, 10 4CG, 10 7CG, 10 13CG). All CBCTs were imported into the computer planning software (CoDiagnostiX, Dental Wings, Montreal, Canada) and the casts from all four groups were scanned with a high-resolution laboratory scanner. The obtained STL files were imported into the computer planning software. For Each obtained DICOM dataset, segmentation was performed; superimposition of the three files was done for all the groups. The accuracy of superimposition was assessed, in millimeters, in three planes corresponding to anterior-posterior, horizontal and vertical planes. Results: The overall analysis demonstrated significant differences between CG and TG7; CG and TG13; TG4 and TG7; TG4 and TG13; TG7 and TG13 with (p<0.001) for all of them. The anterior-posterior dimension demonstrated significant differences between CG and TG7 (P<0.001), CG and TG13 (P<0.001), TG4 and TG7 (p=0.004) and TG4 and TG13 (p=0.001). For the vertical dimension analysis, significant differences were found between CG and TG7 (P<0.001), CG and TG13 (P<0.001), TG4 and TG7 (p=0.023) TG4 and TG13 (p=0.005). For horizontal variable, a statistically significant difference between CG and TG7 (p=0.049), CG and TG13 (p<0.001), TG4 and TG13 (p<0.001) TG7 and TG13 (p=0.003). There was no statistical difference between groups 0 and 4 (p>0.05). The highest discrepancy was observed in TG13 with average of 0.482 mm and the lowest discrepancy was found on control group with average of 0.234 mm. Conclusion: The accuracy of superimposition can be greatly influenced by the number of zirconia crowns artifacts in the CBCT image. This can reflect itself as 0.5 mm in horizontal and 1 mm in vertical directions. The higher the number of zirconia restorations, the lower the accuracy of images’ superimposition. Further research is needed to investigate the effect of different distribution of artifacts on image’s superimposition accuracy.