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. 2020 Feb 27;15(2):e0228266.
doi: 10.1371/journal.pone.0228266. eCollection 2020.

In vitro comparison of the accuracy of four intraoral scanners and three conventional impression methods for two neighboring implants

Elena Roig  1 , Luis Carlos Garza  1 , Natalia Álvarez-Maldonado  1 , Paulo Maia  2 , Santiago Costa  1 , Miguel Roig  1 , José Espona  1
Affiliations

In vitro comparison of the accuracy of four intraoral scanners and three conventional impression methods for two neighboring implants

Elena Roig et al. PLoS One. .

Abstract

Purpose: To determine whether the accuracy of two-implant model impressions taken with optical scanners was inferior to that of those taken with elastomeric materials.

Materials and methods: Impressions of a resin reference model with two almost parallel implants were taken using three elastomeric impressions (closed tray technique, open tray nonsplinted technique and open tray splinted technique) and scanned with four optical scanners (CEREC Omnicam, 3M True Definition Scanner, 3Shape TRIOS3 and Carestream CS 3600). STL files of the different methods were superimposed and analyzed with control software (Geomagic Control X, 3D systems) to determine the mean deviation between scans.

Results: Compared to elastomeric impressions, optical impressions showed a significantly improved mean precision. TRIOS3 and CS3600 showed a significantly improved mean trueness compared to that of closed tray, CEREC Omnicam and TrueDefinition. All methods showed a certain degree of implant rotation over their axes, which was significantly higher in the closed tray and the open tray nonsplinted techniques.

Conclusions: Optical impressions, taken under these in vitro conditions, showed improved accuracy compared with that of elastomeric impressions.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. STL model obtained by scanning the model with the scan bodies screwed onto the implant analogs.
Fig 2
Fig 2. A plane was constructed on top of the scan body (plane 1).
An offset plane was obtained by a -10 mm reduction apically (offset 1). A cylinder was constructed based on the shape and the axis (axis 1) of the scan body (cylinder 1). The intersection of offset 1 and axis 1 was considered the center of the implant head, or centroid (Point 1).
Fig 3
Fig 3. The best fit alignment was used to measure the distance between the two points.
Fig 4
Fig 4. Measuring the distance between the centroids of the two implant heads.
Fig 5
Fig 5. Two planes were constructed on a wall parallel to the implant axis of each scan body, and the angle between them was determined.
Fig 6
Fig 6. Differences between the distance of the two centroids of the test model and the reference model.
Fig 7
Fig 7. The differences in the angle between the two flat horizontal surfaces of the two implants in the test and the reference models.
Fig 8
Fig 8. One-way ANOVA comparing the precision of the methods analyzed.
The optical methods showed significantly more precision than the elastomeric methods did. The open tray impressions were significantly more precise than the closed tray impressions were (p<0.05).
See this image and copyright information in PMC

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