Dr Szuba-Paszkiewicz, what are some of the most common errors that dental professionals make when taking traditional dental impressions?
The most common errors are inadequacies in the surface mapping of the impression materials, including air bubbles, delaminated layers between wash and body material, and shrinkage or extension of the material. Discomfort can be caused for the patient, including the triggering of the gagging effect when there is too much material on the tray. Since there is only one approach for traditional impression taking, no corrections can be made after the impression has been taken.

Taking digital impressions is said to be faster and more precise than taking traditional impressions. However, despite their perceived benefits, digital scanners come with some limitations. Could you name a few, and give dental professionals advice on how to overcome them?
The limitations are most visible when scanning highly reflective surfaces or when there is high mobility tissue. This is most common when scanning edentulous ridges, especially in the mandibular region. Full-arch implant cases are difficult to achieve with sufficient accuracy and precision. However, there are some tricks that help immobilise the tissues, and it is also possible to scan by quadrants. Dental professionals can place some immobile composite or miniature screws onto the tissue to set reference points for the scanner. Alternatively, owing to its ultra-precise passivity for restorations, dental professionals could use a photogrammetric scanner for full-arch implant cases.

In your opinion, in which cases would it be more appropriate to take analogue impressions and why?
Analogue impression taking is more appropriate in cases where there is insufficient fixed pink tissue or edentulous ridge and when the scanner cannot match the surfaces together to achieve a precise 3D image. Long-span implant bridges with more than three implants should also be taken by analogue impression.

Editorial note: The webinar, titled “Digital impression in modern dentistry: The possibilities and limitations of actual procedures. Facing the challenges,” was presented live on Tuesday, 22 June, at 12 p.m. CEST, and is available to be viewed on demand on the FDI Oral Health Campus.

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