06 February 2019

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Is intraoral scanner reliable?

Lorenzo Breschi

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Intraoral impressions with digital scanners are becoming increasingly popular. The speed and reduction of the steps necessary to reach the final product are desirable characteristics in modern dentistry.

But are we working on lower quality standards? 

A systematic review written by Dr. Jaafar Abduo and his group (*), aimed to evaluate the accuracy of the available IOS systems for dental impressioning and to identify the influencing factors on accuracy. Only 32 studies were suitable for the analysis. There is tendency for the studies of this systematic review to support the superior accuracy of PVS and polyether impressions over IOS impression. This observation appears to be dependent on the span of the impression.
For single tooth scanning or for short span abutments impression, the accuracy of IOS impression is similar to the PVS and polyether impression. For whole arch scanning, the studies consistently revealed the superiority of PVS impression over IOS impression.
The authors evidenced that the scanning systems and the powder application do not appear to be a major influencing factor on the accuracy of the impressions. On the other hands, it appears that there is an influence of the scanning sequence and camera movement on the accuracy of the virtual model. Registering the whole arch dimension from each scanning step, for example, appears to be advantageous as it reduces the systematic deviation from stitching of the images. Moreover there is some evidence that smooth surfaces are easier to capture by light scanners in comparison to irregular and corrugated surfaces. Thus it’s reasonable for the clinician to modify the preparation design by ensuring smooth and regular surfaces with rounded internal line angles. 

CONCLUSIONS
General analyzes on intraoral impressions are the daughters of evaluations that concern different scanners at different times; probably even today the defects of the scanners that have emerged in the literature have been corrected.
The clinical reality will give us more information in the future.  

(*) Accuracy of intraoral scanner: a systematic review.