Precision of fast-set impressions – Randomized controlled clinical trial

Objectives: When fast-set impression materials are used for a one-stage impression-technique, the clinical relevance of an exact timing for mixing, applying and syringing both material components is gaining importance. Aim of this clinical trial (RCT) was to determine the influence of a non-optimal timing on the precision of fast-set impressions. Primary objective was the precision of the three-dimensional (3D) tooth surface reproduction as well as the reproduction of the subgingival tooth surface. Methods: Ninety-six probands were included and three one-stage impressions each were taken with either a polyether (PE: Impregum Penta H/L DuoSoft Quick, 3M ESPE, Germany) or an addition-curing silicone (AS: Aquasil Ultra LV, Dentsply DeTrey, Germany). The impression taken with optimal timing was chosen as reference. The two additional impressions were taken with two out of eight different non-optimal timings. The order in which the three impressions were taken as well as the material and the non-optimal timing were assigned to each proband according to a randomization list. Standardized-made master-casts were digitized and the data resulting from the non-optimal timed impressions was compared to the reference in order to access the 3D precision as well as the subgingival reproduction. Statistical analysis was performed using multivariate models. Results: Mean values for tooth 46 ranged from +/- 12 microns for PE to +19 and – 14 microns for AS. Significantly higher mean values (62 to -40 microns) were found for AS in contrast to PE (21 to -26 microns) in the area of the distal neighboring tooth. The reproduction of the subgingival tooth area did not show any significant differences. Conclusion: The machine-mixed polyether material showed a significantly higher precision in the distal lower jaw, where the influence of saliva, swallowing and deformation due to impression removal is increasing.

The dental company 3M ESPE AG in Seefeld, Germany, supported this study.