Accuracy of a New Automixed VPS-Material Using a Standardized Abutment-Model

Objectives: Auto-mixing procedures are gaining popularity to improve standardization of impression taking. Most of the materials, dispensed from an auto-mixing device, are of medium- or heavy-body viscosity. Recently, a new auto-mixed vps-material (Express Penta Putty = EPP, 3M ESPE, Seefeld) was introduced to the market. It was the aim of this study to evaluate the accuracy of impressions taken with EPP in a standardized in-vitro setup and to compare it to a commercially available vps-material (Panasil Putty fast set = PPFS, Kettenbach) and a C-Silicone (Optosil Comfort = OC, Heraeus-Kulzer), respectively. Methods: A master-model, consisting of four cylindrical test-abutments with parallel sided areas, fixed on a metal plate and completed with an acrylic mask to a lower jaw model, was used. The master-model and the impression trays were mounted in a Zwick1454 testing device (Zwick-Roell, Ulm) to standardize impression procedure. 20 two-stage putty-wash impressions per group were taken using EPP, PPFS and OC, respectively, at the end of the recommended working time (N=10) and as quick as possible (N=10). Force of impression taking was determined during impression procedure. Stone models were poured >1h after impression taking and stored for 7 days prior to measuring the diameters of the test-abutments (DTU). Data were subjected to parametric statistics (ANOVA: p=0.05). Results: Average discrepancy of DTU ranged from -0.5 to -1.75 %. Significant differences were observed between the vps-materials (p<0.05) and the vps-materials and c-silicone (p<0.05), respectively for both working times. Force during impression taking was significantly higher for PPFS compared to EPP and OC (p<0.05). EPP showed the same force during impression taking as OC (p>0.05). Conclusions: Within the limits of the study it can be concluded, that discrepancy between DTU and master abutment was lowest for EPP. Pressure during impression taking of EPP was comparable to the c-silicone.