Effect of Auxiliary Devices on the Accuracy of Complete‑Arch Implant Digital Impressions: An in Vitro Study

Abstract

Purpose

To evaluate the effectiveness of the auxiliary device in acquiring implant and soft tissue data using intraoral scanning and its influence on the accuracy of digital impressions for edentulous implants.

Methods

Three standardized implant models for edentulism, categorized as 2-4, 2-5 and 2-4-6, were designed and printed based on the distribution of implants. Various auxiliary devices were designed for each model, and an artificial gingiva with cube-like marking points was created to test the completeness of soft tissue information capture. The models were scanned using an extraoral model scanner to obtain accurate baseline data. Intraoral scans (Trios 4) were performed before and after adding auxiliary devices. The scan data were evaluated using inspection software. The linear distances of center point of upper plane between scan body was calculated. The Shapiro–Wilk normality test, independent-samples t test, and Mann–Whitney nonparametric test were used for statistical analysis. Statistical significance was set at α = 0.05.

Results

The trueness and precision of most loci improved with the inclusion of auxiliary devices, surpassing their counterparts without such devices. Notably, trueness advanced in: the 2-4 group using 2.5-mm-wide smooth-surface (W2.5-S) for the longest span (#14-#24) [decreased from (0.123 ± 0.034) mm to (0.081 ± 0.033) mm]; the 2-5 group employing 2.5-mm-wide cube-like (W2.5-C) and hemisphere-like(W2.5-H) devices for the longest span (#15-#25), (decreased from [0.155 ± 0.061] mm to [0.028 ± 0.017] mm and [0.035 ± 0.019] mm); and the 2-4-6 group with W2.5-C and W2.5-H devices for loci #16-#24 [decreased from (0.091 ± 0.056) mm to (0.055 ± 0.033 mm and (0.054 ± 0.041) mm] and #16-#26 (decreased from [0.148 ± 0.112] mm to [0.088 ± 0.041] mm and [0.084 ± 0.047] mm) (P < .05). Adding the devices did not affect the root-mean-square values of the soft tissue marker points.

Conclusions

The use of auxiliary devices enhances the accuracy of digital impressions for edentulous implant restorations obtained using intraoral scanners while also capturing complete soft tissue information.