Accuracy evaluation of intraoral optical impressions: A clinical study using a reference appliance

Abstract

Statement of problem Trueness and precision are used to evaluate the accuracy of intraoral optical impressions. Although the in vivo precision of intraoral optical impressions has been reported, in vivo trueness has not been evaluated because of limitations in the available protocols. Purpose The purpose of this clinical study was to compare the accuracy (trueness and precision) of optical and conventional impressions by using a novel study design. Material and methods Five study participants consented and were enrolled. For each participant, optical and conventional (vinylsiloxanether) impressions of a custom-made intraoral Co-Cr alloy reference appliance fitted to the mandibular arch were obtained by 1 operator. Three-dimensional (3D) digital models were created for stone casts obtained from the conventional impression group and for the reference appliances by using a validated high-accuracy reference scanner. For the optical impression group, 3D digital models were obtained directly from the intraoral scans. The total mean trueness of each impression system was calculated by averaging the mean absolute deviations of the impression replicates from their 3D reference model for each participant, followed by averaging the obtained values across all participants. The total mean precision for each impression system was calculated by averaging the mean absolute deviations between all the impression replicas for each participant (10 pairs), followed by averaging the obtained values across all participants. Data were analyzed using repeated measures ANOVA (α=.05), first to assess whether a systematic difference in trueness or precision of replicate impressions could be found among participants and second to assess whether the mean trueness and precision values differed between the 2 impression systems. Results Statistically significant differences were found between the 2 impression systems for both mean trueness (P=.010) and mean precision (P=.007). Conventional impressions had higher accuracy with a mean trueness of 17.0 ±6.6 µm and mean precision of 16.9 ±5.8 µm than optical impressions with a mean trueness of 46.2 ±11.4 µm and mean precision of 61.1 ±4.9 µm. Conclusions Complete arch (first molar-to-first molar) optical impressions were less accurate than conventional impressions but may be adequate for quadrant impressions.

Intrasubject comparison of digital vs. conventional workflow for screw‐retained single‐implant crowns: Prosthodontic and patient‐centered outcomes

“…to the conventional impression technique, the dental models based on digital impressions were found equally accurate using various IOS systems (Ender & Mehl, 2011Guth, Edelhoff, Schweiger, & Keul, 2015;Guth, Keul, Stimmelmayr, Beuer, & Edelhoff, 2013;Keul et al, 2014;Koch, Gallucci, & Lee, 2016). The data are consistent for partial impressions, but controversies remain for the full-arch impression (Atieh, Ritter, Ko, & Duqum, 2017;Moreira, Rodrigues, Pinho, Fonseca, & Vilaca, 2015;Papaspyridakos et al, 2015). The in vivo precision of several dental impression systems was also investigated both for quadrant and complete arch digital impressions and compared with the conventional technique.…”

Accuracy of Dynamic Virtual Articulation: Trueness and Precision

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Influence of Tooth Preparation Design and Scan Angulations on the Accuracy of Two Intraoral Digital Scanners: An in Vitro Study Based on 3‐Dimensional Comparisons

“…Some intraoral scanners use zinc oxide or titanium oxide powders in the scanning protocol. However, recent intraoral scanners usually do not require powder in their scanning protocol and seem to have comparable or better accuracy to that of the powdered protocol 18‐20 . Two different intraoral scanners representing the traditional powder protocol scanner, the True Definition (3M TM ESPE, St. Paul, MN) (TRU) and the powder‐less protocol scanner, the TRIOS® (3Shape, Copenhagen, Denmark) (TRI), were chosen for this in vitro study.…”