Objectives: The quality of impressions is decisive for the fit and consequently for the success of a prosthodontic reconstruction. It was therefore the purpose of this investigation to evaluate the accuracy of two different impression techniques – an one-step (OSPW) and a two-step putty-wash technique (TSPW) – using a digital scanning technology.

Material and Methods: 60 bovine incisors were prepared with diamond burs under constant water cooling to achieve a standardized clearly visible finishing line. Two impressions per tooth were taken (OSPW- and TSPW-technique, resp.) using a polyvinylsiloxane (Imprint-II heavy and light body, 3M-ESPE, Seefeld) with custom trays. Only the impressions with exactly reproduced finishing lines from all prepared teeth were included in the investigation. The prepared original teeth as well as the corresponding working casts were scanned with an optical scanning system (diGident, Girrbach Dental-Systeme, Pforzheim). Data of each specimen were imported into Metris Software (Metris NV, Leuven) for determination of the surface, volume and 3-dimensional difference compared to the original tooth. Data were subjected to non-parametric statistics (U-Test, p=0.05).

Results: For both techniques, the working casts were smaller than the original tooth. However, the differences related to the original tooth surface (s) and volume (v) were higher for the TSPW technique (s:4.24%, v:3.01%) compared to the OSPW technique (s:3.59%, v:1.81%). Differences were not significant (p>0.05).

Conclusions: Within the limits of this study it can be concluded that both impression techniques - using Imprint II as impression material - have the potential for clinical acceptable results. However, there is a tendency for a better accuracy for the OSPW technique.

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