There are many clinical studies available concerning intraoral scanning. The following are a few conclusions from some of them.
"Within the limitations of this study, the zirconia copings fabricated with CAD-CAM using different digitization methods and Ni-Cr copings fabricated using the lost-wax technique and casting produced clinically acceptable marginal and internal discrepancies. No significant differences were found."
Evaluation of the fit of zirconia copings fabricated by direct and indirect digital impression procedures. Lee B et al, 2017
"In dentate situations, the two tested IOS systems achieved a clinically satisfying accuracy for capturing gingival contour in anterior maxilla, with a comparable or superior precision to the conventional impression. Intraoral digital impressions could be a recommended method to record 3-dimensional gingival contour in the esthetic zone."
Evaluation of intraoral digital impressions for obtaining gingival contour in the esthetic zone: accuracy outcomes. Wei D, 2020
"Within the limitations of this in vivo study, all of the digital impression systems were capable of measuring quadrant impression with clinically satisfying precision. There are differences in precision between different digital impression systems, but while statistically significant, they all fall within a range which allows the successful production of restorations in the digital workflow."
In vivo precision of conventional and digital methods for obtaining quadrant dental impressions. Ender A, 2016
"The curtain that doctors have been hiding behind: the one that says digital is no good or the quality isn’t there, no longer exists", says Dr. Vincent Prestipino, Prosthodontist.
As seen from these studies, digital impressions deliver equal if not better results when compared with analog impressions. Thankfully there is now extensive clinical research in this area. In this piece, we have given you a introduction and a glimpse of what they say. On the 3Shape website you can find a complete library clinical studies to review.