15 October 2022

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Full-arch implant rehabilitation: digital or traditional impression?

Simona Chirico

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Digital dental technology has recently gained considerable popularity and has now been widely incorporated into the prosthetic and implant workflow. Dentists working with edentulous patients have not always used traditional impressions when creating a full arch prosthesis on implants.  

The introduction of digital technology, however, allows digital impressions to be made through intraoral scans, even in edentulous patients. It can even be done during a complex procedure due to the absence of anatomical landmarks, such as teeth. The accuracy of this approach is widely discussed in scientific literature. 

Materials and methods 

The study published by Chochlidakis et al. compared the accuracy of digital impressions with traditional ones in the rehabilitation of completely edentulous patients using full-arch prostheses on implants. 

Sixteen patients were analyzed in the study. Patients who had been completely edentulous for at least one year and who were wearing conventional full dentures in at least one jaw — and who did not require vertical or horizontal grafting procedures — were included in the study. 

Conventional impressions were produced for all patients, scanned subsequently with a desktop (extraoral) scanner and digital impressions were created via full-arc digital intraoral scans. The extraoral and intraoral scans were superimposed and analyzed with reverse engineering software.  

The main outcome was to evaluate the accuracy between conventional impression scans and full arch fingerprints. The secondary outcome, on the other hand, was to evaluate the effect of the number of implants on the 3D (3 Dimensional) precision of the impressions using the Spearman coefficient. 

Results 

The 3D deviations between the full-arch intraoral and extraoral virtual scans of the casts generated from conventional impressions were found to be 162 ± 77 microns.  

In the 4-implant group, 5-implant group and 6-implant group, the 3D deviations were found to be 139 ± 56 μm, 146 ± 90 μm and 185 ± 81 μm, respectively. A positive correlation was found between the increase in the number of implants and 3D deviations, but the differences were not statistically significant. 

Conclusions 

From the study data, researchers concluded that the 3D precision of digital scans to create prostheses on full arch implants falls within a clinically acceptable threshold. 

Chochlidakis, Konstantinos et al. "Digital Versus Conventional Full-Arch Implant Impressions: A Prospective Study on 16 Edentulous Maxillae." J Prosthodont. 2020 Apr;29(4):281-286. doi: 10.1111/jopr.13162.