Accuracy of digital impressions versus conventional impressions for 2 implants: an in vitro study evaluating the effect of implant angulation

Jaafar Abduo,Joseph E A Palamara

doi:10.1186/s40729-021-00355-6

Jaafar Abduo, Joseph E A Palamara

Open Access

https://doi.org/10.1186/s40729-021-00355-6

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Abstract

BackgroundAccurate implant impression is an essential requirement for the fabrication of implant prosthesis. This in vitro study evaluated the accuracy of digital impressions by intraoral scanner (IOS) systems in comparison to conventional impressions for recording the position of 2 parallel implants and 2 divergent implants.Materials and methodsIn vitro 3-unit prosthesis master models with 2 tissue level implants were fabricated; one model had parallel implants, and the other model had one 15° tilted implant. The conventional open-tray impressions were obtained with non-splinted (NSP) and splinted (SP) impression copings. Trios 4 (TS), Medit i500 (MT), and True Definition (TD) were used to make digital impressions with scan bodies. A total of 10 impressions were obtained with every technique. The virtual test images of the conventional and digital impressions were converted to 2 virtual implant images. For each group, trueness, precision, inter-implant distance deviation, and angle deviation were measured.ResultsThere was a general tendency for digital impressions to provide a more accurate outcome for trueness, precision, and angle deviation. The 2 conventional impressions showed similar accuracy, except for the angle deviation, where the NSP was significantly inferior than SP (p < 0.01) for the divergent implants model. The TD was generally the least accurate among all the IOS systems, especially for the inter-implant distance deviation (p < 0.05).ConclusionsWithin the limitations of the laboratory set-up of the present study and the limited clinical resemblance, the digital impressions appeared to have sufficient accuracy for 2 implants and were least affected by the presence of angle between implants. The most inferior outcome was observed for the NSP technique.

Highlights

Accurate implant impression is an essential requirement for the fabrication of implant prosthesis
In relation to trueness (Fig. 3), for the parallel implants model, the most accurate results were for Trios 4 (TS) followed by Medit i500 (MT), True Definition (TD), and SP impressions respectively
The difference was significant between the NSP impression and all the digital impressions only (p < 0.05), and no significant difference was observed between the other groups

Summary

Introduction

Accurate implant impression is an essential requirement for the fabrication of implant prosthesis. To simulate a routine IOS workflow, the experiment implemented reverse engineering of the recorded scan bodies for the purpose of direct evaluation of the virtual implants position This is different from the majority of the published studies that evaluated the accuracy of the scanned surface of the scan bodies with or without the surrounding tissue [15, 21,22,23, 25]. The relevance of this step is that the virtual implants position is the determining factor of the accuracy of any impression technique. The null hypotheses where there is no difference between the different digital impressions and the conventional implant impressions, and there is no effect of the presence of divergence angle between the 2 implants

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Discussion

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