Intraoral scanners (IOS) can be used to create impressions for dental indications within orthodontics, implantology, prosthodontics and as a tool for monitoring changes in the patient’s dentition. An important part of the treatment workflow is the trust that you, as a doctor, have that a scanner can be used reliably. It all starts with the scan, after all.
Scan quality is measured in terms of accuracy. In this article, I will give you a walkthrough of what accuracy is, how it is measured, how it affects your treatment and how you can interpret accuracy data in clinical studies. I’ll highlight a few clinical studies that have been conducted on intraoral scans over the past years and walk you through their conclusions.
Accuracy is the major method in evidencebased research to assess the quality of intraoral scans for clinical use. The consensus on what Accuracy stands for is documented in the ISO 5725-1 standard1, and comprises two elements:
Closeness of agreement between mean of test versus the true reference value.
Closeness of agreement between test results.
Accuracy is regarded as one of the major differentiators for IOS capabilities2. When assessing accuracy studies within the Clinical literature, it is important to be aware of the distinction between in vitro or in vivo. Both are important.
Accurate intraoral 3D models facilitate patient diagnosis, optimal treatment workflows and treatment outcome evaluation. Conventional impressions, whilst widely used for the same treatment purposes, can cause errors when translated into a digital format. This can impact the accuracy of the patient model which treatments are based on.
Our clinical research department keeps a close eye on the research being done on digital technologies in dentistry. Our ebook "Intraoral scanning and treatment quality" gives you a deep dive - with practicioner`s experiences.
For example, impression taking using the conventional method can result in errors such as air bubbles, whereas this problem is eliminated using an IOS.
Furthermore, a digital scan can be stored more easily with no risk of changes because of environmental factors, which is a risk with gypsum models. Think for example of model breakage, or shrinking or expanding during lab transit.
The replicability of taking an IOS is also considerably easier, more comfortable for the patient and less time consuming4. Both conventional and digital impressions require training. This is an important factor in accuracy: poor digital impression taking can affect the treatment workflow by reducing accuracy of the scan. However, the learning curve for sufficient impression taking has been shown to be faster with IOS compared with conventional impression taking methods5.
During the past years, there’s been a lot of studies that compare accuracy of digital impression methods against each other or against conventional impression taking methods. Below, I will highlight a few of the studies where accuracy of intraoral scanners is thoroughly reviewed and compared.
Find out how treatment quality is affected by using intraoral scanning. From clinical studies to practitioners' experiences.
1. Https://www.iso.org/obp/ui/#iso:std:iso:5725:-1:en. ISO 5725-1:1994(en) Accuracy (trueness and precision) of measurement methods and results.
2. Kihara H, Hatakeyama W, Komine F, et al. Accuracy and practicality of intraoral scanner in dentistry: A literature review. J Prosthodont Res. 2020;64(2):109-113. doi:10.1016/j.jpor.2019.07.010
3. Nedelcu R, Olsson P, Nyström I, Rydén J, Thor A. Accuracy and precision of 3 intraoral scanners and accuracy of conventional impressions: A novel in vivo analysis method. J Dent. 2018;69(November 2017):110-118. doi:10.1016/j.jdent.2017.12.006
4. Glisic O, Hoejbjerre L, Sonnesen L. A comparison of patient experience, chair-side time, accuracy of dental arch measurements and costs of acquisition of dental models. Angle Orthod. 2019;89(6):868-875. doi:10.2319/020619-84.1
5. Kouveliotis G, Tasopoulos T, Karoussis I, Silva NR, Zoidis P. Complete denture digital workflow: Combining basic principles with a CAD-CAM approach. J Prosthet Dent. Published online February 2021. doi:10.1016/j.prosdent.2020.12.024
6. Amornvit P, Rokaya D, Sanohkan S. Comparison of Accuracy of Current Ten Intraoral Scanners. Grassia V, ed. Biomed Res Int. 2021;2021:2673040. doi:10.1155/2021/2673040
7. Nulty AB. A Comparison of Full Arch Trueness and Precision of Nine Intra-Oral Digital Scanners and Four Lab Digital Scanners. Dent J. 2021;9(7). doi:10.3390/dj9070075
8. Kim RJY, Benic GI, Park J-M. Trueness of ten intraoral scanners in determining the positions of simulated implant scan bodies. Sci Rep. 2021;11(1):2606. doi:10.1038/s41598-021-82218-z
9. Diker B, Tak Ö. Accuracy of Digital Impressions Obtained Using Six Intraoral Scanners in Partially Edentulous Dentitions and the Effect of Scanning Sequence. Int J Prosthodont. 2021;34(1):101-108. doi:10.11607/ijp.6834
10. Gutmacher Z, Kelly A, Renne W, et al. Evaluation of the accuracy of multiple digital impression systems on a fully edentulous maxilla. Quintessence Int. 2021;52(6):488-495. doi:10.3290/j.qi.b1244373