Effect of auxiliary geometric devices on the accuracy of intraoral scans in full-arch implant-supported rehabilitations - an in vitro study.

OBJECTIVES: the aim of the present in vitro study was to evaluate the effect of a novel auxiliary geometric device (AGD) on the accuracy of full-arch scans made with 3 different intra-oral scanners (IOS).

METHODS: An edentulous maxillary model with four internal connection implant replicas was scanned using three different IOS: iTero Element 5D (ITERO) (Align Technology, Tempe, AZ, USA), Trios 4 (TRIOS) (3Shape A/S Holmens Kanal 7 1060 Copenhagen Denmark), and Carestream 3700 (CS) (Carestream Dental, Atlanta, USA). Thirty-six scans were taken with each IOS, 18 with the AGD in place, and 18 without the AGD. A digital master model was created using an industrial optical structured light scanner (ATOS compact Scan 5M, GOM GmbH, Braunschweig, Germany). The master and IOS models were aligned using the scan bodies as a reference area. A surface comparison was performed, and deviation labels were exported for each scan body to evaluate the linear and angular deviation. Total body and platform deviations, and angular deviations were measured.

RESULTS: The use of AGD resulted in a statistically significant increase of angular deviation: 0.87° (SD=0.21) in the AGD group versus 0.64° (SD=0.46) in the no AGD group (p-value=0.005). The difference between the AGD and no AGD groups was not statistically significant for total body and platform deviation values (p-value=0.051 and 0.302 respectively). Using AGD, ITERO showed a statistically significant increase in angular deviation (mean difference=-0.46 µm, p-value=0.002) and a decrease in mean platform deviation (mean difference=63.19 µm, p-value<0.001). No statistically significant differences were found for the other IOSs.

CONCLUSIONS: The use of auxiliary geometric devices (AGD) did not add benefit on CS and TRIOS. On ITERO there is an improvement in platform deviation that is outweighed by the worsening of the angular deviation.

CLINICAL SIGNIFICANCE: In vitro data suggest that intraoral scans can be successfully used in full-arch cases. The use of AGD has no additional benefit on CS and TRIOS. On ITERO there is an improvement in platform deviation that is outweighed by the worsening of the angular deviation. Translational application to clinical practice deserves further investigation, taking into account patients' related and anatomical variables.