The Influence of Hard- and Software Improvement of Intraoral Scanners on the Implant Transfer Accuracy from 2012 to 2021: An In Vitro Study

Abstract

This study aimed to investigate the transfer accuracy (trueness and precision) of three different intraoral scanning families using different hardware and software versions over the last decade from 2012 to 2021, compared to a conventional impression. Therefore, an implant master model with a reference cube was digitized and served as a reference dataset. Digital impressions of all three scanning families (True definition, TRIOS, CEREC) were recorded (n = 10 per group), and conventional implant impressions were taken (n = 10). The conventional models were digitized, and all models (conventional and digital) were measured. Therefore, it was possible to obtain the deviations between the master model and the scans or conventional models in terms of absolute three-dimensional (3D) deviations, deviations in rotation, and angulation. The results for deviations between the older and newer scanning systems were analyzed using pairwise comparisons (p < 0.05; SPSS 26). The absolute 3D deviations increased with increasing scan path length, particularly for the older hardware and software versions (old vs. new (MW ± SD) True Definition: 355 ± 62 µm vs. 483 ± 110 µm; TRIOS: 574 ± 274 µm vs. 258 ± 100 µm; and CEREC: 1356 ± 1023 µm vs. 110 ± 49 µm). This was also true for deviations in rotation and angulation. The conventional impression showed an advantage only regarding the absolute 3D deviation compared to the older systems. Based on the data of the present study, the accuracy of intraoral scanners is decisively related to hardware and software; though, newer systems or software do not necessarily warrant improvement. Nevertheless, to achieve high transfer accuracy, regular updating of digital systems is recommended. The challenge of increasing errors with increasing scan paths is overcome in the most recent systems. The combination of two different scanning principles in a single device seems to be beneficial.

Accuracy of digital implant impressions in clinical studies: A systematic review

“…In the study by Chochlidakis et al (Chochlidakis et al, 2020), the True Definition IOS was used, and the deviations were also very high. A study by Schmidt, Schlenz, et al (2021) confirmed that no better result was achieved with the True Definition IOS with its newer hardware generation in combination with newer software version. As the True Definition Scanner works on the active wavefront sampling recording principle with structured light projection and relies on the use of powder (Logozzo et al, 2014), the lower use of powder recommended by the manufacturer could hypothetically be responsible for the lower accuracy.…”

“…Similar results have been reported in in vitro studies from the same time (Nedelcu & Persson, 2014; Patzelt, Bishti, et al, 2014). Newer hardware devices or software versions of the scanners can lead to more accurate results (Schmidt, Schlenz, et al, 2021). The findings of another study also showed high deviations (Alsharbaty et al, 2019), and an older version of the TRIOS IOS was used in this study.…”

“…While the use of a best‐fit method typically produces numerically lower values, the values of a three‐dimensional measurement were significantly higher. This method tends to hide real differences (Ameza‐Lasuen et al, 2020; Schmidt et al, 2021, 2021a). However, this becomes apparent only when an external reference structure is used and is seen as a benchmark, without which the actual deviations in the transfer of the intraoral to the extraoral situation cannot be estimated.…”

“…However, even though the digital system should help avoid errors in the conventional process chain, errors can also occur in the digital workflow. The selected scanpath (Ender & Mehl, 2013; Müller et al, 2016), the user (Rutkunas et al, 2017), a lack of calibration (Rehmann et al, 2017), the software or hardware version (Haddadi et al, 2018; Schmidt, Schlenz, et al, 2021; Shim et al, 2015; Vag et al, 2021), and scanbody used (Schmidt et al, 2019; Schmidt et al, 2021b) are possible factors that influence the accuracy.…”

Reader’s Forum

“…2 - 4 Therefore, it is important to scan the arch according to the manufacturer’s instructions. Other factors associated with the scan data accuracy are scanner software versions, 5 , 6 ambient lights, 7 and scanning skills. 8 In our study, an intraoral scan was performed following the manufacturer’s instructions to minimize errors during data capturing.…”