Influence of scan pattern on full-arch scans with three digital scanners

Objectives Digital imaging has become one of the standard procedures in dental practice. A variety of different intraoral scanners are available for this purpose. A universally valid and accepted procedure for digitizing a specific anatomical situation is not yet available. This makes it difficult to obtain an accurate and reproducible result. The aim of the study was to develop a standardized workflow that improves quality and guarantees precise results regardless of the scanner type. The deviations between the data record and the original should be as small as possible.

Material & methods The data sets were collected from eight different scan protocols and compared with a master scan (laboratory scanner). The protocols were applied five times to a test jaw. The data were collected with three different intraoral scanners in a light box with identical lighting conditions. To quantify the deviations, the scans were superimposed and the deviations in regio 41 and 47 were compared. The statistical analysis was carried out by an ANOVA and a Tukey-HSD post-hoc test.

Results None of the strategies proved to be superior overall. The deviations were on average 0.57mm (SD ± 0.13mm) in the anterior region and 0.72mm (± 0.3mm) in the posterior region. Strategy 3 (swiping movements from 37 to 47 along the dental arch) was able to generate the most accurate data for the anterior region with mean deviations of 0.52mm (± 0.117mm) and strategy 5 (lingual from 37 to 47 - occlusal from 47 to 37 - vestibular from 37 to 47) for the posterior region with mean deviations of 0.61mm (± 0.3mm). Differences between the different scanners were also detected.

Conclusions Depending on the target or size of the digital impression, choosing the right scanning strategy can increase the “accuracy and precision” of the data set. Not only the target region, but also the scanner used should be considered. The available results cannot identify a generally superior strategy currently. This is of particular importance, as deviations in the digital impression can affect the "fit accuracy"of dental restorations. Nevertheless, the aim of further comparative studies should be to develop a universal scanning method that delivers consistently realistic, accurate and precise results regardless of the scanner.