Don’t Take All Published Dental Product Research at Face Value

  • <<
  • >>

Dentalcompare
Clinical Director
 Dentalcompare Blog: Don’t Take All Published Dental Product Research at Face Value

There has been an increasing amount of attention to the world of digital impressions, especially with the addition of a few new players such as Carestream’s CS 3500 or the FastScan from IOS Technologies. Your patients are hearing about it too.

Just last week the Wall Street Journal published an opinion piece, albeit an uninformed one, touting the convenience of CAD/CAM dentistry, but questioning the accuracy and esthetics. They definitely got it wrong, but it is a reminder that we need to know what they got wrong so we can educate our patients when they have questions. The article does allude to the need for more studies on dental CAD/CAM, but even with numerous new studies underway, it is important to think critically about what is being published.

Take, for example, this research article on the accuracy and precision of an intraoral scanner (Invisalign’s iTero), and a desktop scan of a stone model (completed using the D250 from 3Shape). The researchers compared 10 intraoral scans from the iTero, 10 stone model scans with the iTero, and 10 stone model scans with the D250. They looked at each one to determine errors between scans. What they found was that the 10 scans from the intraoral iTero were the most dissimilar, to the tune or 50 microns. They compared that to the D250 scans of the stone model, with only 10 micron deviation, and declared the desktop scanner superior.

The problem here is the methods and conclusion of this study are poorly constructed. They are comparing two very different systems that achieve their results with very different means. They are saying that repeated scans with iTero were not as accurate as model scanning with 3shape, but then the implication is that the latter is better. All it really says is that the 3Shape does really well on a static model, time after time, not that it is better than iTero.

The obvious omission is the inherent inaccuracies contributed by the impression material itself, combined with the setting of the stone model, and all the other places errors can be introduced into the process of taking a physical impression and pouring a model. In other words, how much did that model differ from the original oral structures?

Further, where the most deviations occurred with the iTero was on facial surfaces. This could be more of a stitching error than camera accuracy, but the researchers didn’t go there.

This study was published in the American Journal of Orthodontics. The big picture question here is whether or not an orthodontist will get accurate results from using the iTero. The way the study is presented it leads the reader to the wrong conclusion. If you really want to understand the relevancy of digital impression technology, you have to consider the entire clinical outcome.

For example, does the 50 micron difference between scans really matter when considering the inherent accuracy of the Invisalign aligners that can be created from this scan? Plus, Invisalign as a system is much more accurate than placing brackets by hand, or eye-balling the bend of a wire. What also seems to be completely missing is a comparison to the accuracy of the current way Invisalign generates its digital models, and how that compares to the iTero. (Studies of this have been completed by Invisalign).

The important lesson here is this: just because something is published, doesn’t necessarily mean it can be taken for face value. It is always important to look at the details, and determine whether or not the information given can be integrated into a set of facts used to do the job of dentistry. This goes for research articles, lectures at conventions, or marketing speak from manufacturers.

Comments

-->