Guided Scanning Improves Full Arch Precision of an Intra-Oral Scanner

Objectives: To compare the precision of two intra-oral scanner software packages, the CEREC Software (CSW Version 4.5.2) and the guided scanning software CEREC Ortho Software (COSW Version 1.1.2), in capturing implant position and angulation over a full arch.
Methods: A cobalt chrome model of a maxillary arch was created with six dental implants (WINSIX; BioSAFin) milled into the surface. The implants were positioned bilaterally at the canine, premolar and molar regions. Scan bodies facilitated data capture. An intraoral scanner (CEREC Omnicam; Sirona Dental Systems GmbH) was calibrated according to the manufacturer’s instructions. Ten full arch scans were obtained using each software package (CSW and COSW). Analysis was performed using custom software written with the Visualization Toolkit (http://www.VTK.org). Six identical CAD implant files were aligned to each scan and ten reference points were uniformly selected around the circumference of each CAD implant. The distances between corresponding points were recorded for each combination of implant-pairs. The angles between the long axes of each implant-pair were also obtained. The range of the 95% confidence intervals (CI) for both distance and angle was plotted against the inter-implant distance.
Results: The range of 95% CI for distance increased with the inter-implant distance for CSW (regression coefficient = 0.0015, p<0.001) and COSW (regression coefficient = 0.0004, p=0.002).The range of 95% CI for angle was associated with the distance between implants for CSW (p=0.04) but not for COSW (p=0.52). There were more fluctuations of the range of 95% CI for the distance and the angle for CSW than for COSW.
Conclusions: The COSW was more precise in capturing implant position and angle over increasing inter-implant distances. These findings may be the result of a reduction in cross arch warping with the COSW.