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Conventional Impressions and Digital Scans for All-on-Four Treatment

Now online in the Journal of Prosthodontics, an original research article co-authored by ACP member, Walaa Magdy Ahmed, BDS, MSc, Dip (Pros) PhD, FRCDC.

This study compared the accuracy of digitizing conventional impressions to intraoral surface scans for all-on-four treatment in the maxillary arch, in terms of trueness and precision.

An edentulous maxillary polymerized PMMA 3D-printed resin model with three built-in landmarks was prepared and four implants with internal connections were placed and positioned according to the all-on-four treatment design. The study evaluated and compared the accuracy (precision and trueness) of the digital intraoral scan of the model using a Trios 3 intraoral scanner, and scan bodies and a conventional open tray impression that was digitized using the same scanner.

The present study found no statistically significant difference between the trueness of intraoral surface scans and conventional impressions; however, the results suggest that intraoral surface scans are more accurate than conventional impressions for the all-on-four treatment design in both straight and angled situations without a statistically significant difference.

One of the limitations of this study was that it was an in vitro study. The vast difference in the reflective and refractive indices of the model material versus intraoral soft tissues might affect the accuracy. Within the limitations of the study, the digital groups showed an advantage over the conventional groups suggesting that intraoral surface scan is comparable in terms of trueness and precision.

Marshaha, N, Azhari, AA, Assery, M, Ahmed, WM. Evaluation of the trueness and precision of conventional impressions versus digital scans for the all-on-four treatment in the maxillary arch: an in vitro study. J Prosthodont. 2023; 00– 00. https://doi.org/10.1111/jopr.13666

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