The accuracy of digital impression with different intraoral scanners on maxillary all on four implants: an in vitro study

Abstract

Objectives: This study aimed to evaluate the effect of 30° angulation of (All-on-four) implants on the accuracy of digital impressions using different intra-oral scanners in the maxillary edentulous arch in terms of trueness and precision.

Materials and methods: A maxillary completely edentulous model was 3D printed with four-cylinder holes measuring 4.3*10 mm, creating space for implant analogs at the canines and second premolar areas. The two anterior implants were placed parallel to each other with 0-degree angulation at the site of the canines, while the two posterior implants were placed at the site of the second premolars with 30° distal angulations. Four peek scan bodies were screwed to analogs. The model is scanned using an EOS X5 desktop scanner and set as a reference model. Afterward, three groups of intraoral scanners group 1 (Trios3shape), group 2 (Medit I700), and group 3 (Launca DL-202) were used to scan the model. Seven scans of the model were performed for each scanner following the manufacturer protocol. The trueness and precision of each intraoral scanner were virtually tested using the Gemoagic Control X software program.

Results: Regarding trueness, there was a statistically significant deviation between the three intraoral scanners recording 38, 44, and 229 μm for the Trios, Medit I-700, and Launca scanners, respectively, while there was no statistically significant difference in precision between the Trios and Medit I700 scanners.

Conclusions: The Trios scanner was the most accurate regarding trueness and precision for recording the maxillary full arch implants, followed by the Medit I-700, and the Launca scanner due to the ability of the Trios scanner to scan the posterior angulated implants as accurately as the anterior straight ones. Also, the scanner technology separately doesn't affect scanning accuracy, but other factors should be taken into consideration such as scanner design and scanner head size.

Clinical relevance: The type of intraoral scanner used in full arch cases greatly affects the accuracy of digital impressions, which may affect the fit of future prostheses, so the operator should carefully choose the proper optical scanner.

Keywords: All on four; Digital impression; Full arch implants; Implants; Intra-oral scanning.

Fig. 1

Virtual setting of artificial teeth on the maxillary edentulous model to determine the implant position according to the prosthetically driven implant placement concept

Fig. 2

The 3D printed model with four cylindrical holes with the implant analogs attached to it

Fig. 3

The 3D printed model with four scan bodies attached to the implant analogs

Fig. 4

Superimposition between the two digital impressions representing the comparator group and the reference model

Fig. 5

(A) Picked up occlusal comparison points on the scan body head (B) Picked up mid-axial comparison points on the scan body head

Fig. 6

Color map representing trueness and precision in root mean square in the three studied groups (A) Trueness of the Lanuca IOS group (B) Trueness of the Medit I700 IOS group (C) Trueness of the Trios IOS group (D) Precision of the Lanuca IOS group (E) Precision of the Medit I700 IOS group (F) Precision of the Trios IOS group

Fig. 7

Bar chart representing the trueness of the three digital impression groups in the straight anterior implants and the angled posterior implants

Fig. 8

Bar chart representing the precision of the three digital impression groups in the straight anterior implants and the angled posterior implants