Accuracy of Single-Step versus 2-Step Double-Mix Impression Technique

الملخص EN

Objective.

To investigate the accuracy of dies obtained from single-step and 2-step double-mix impressions.

Material and Methods.

Impressions (n=10) of a stainless steel die simulating a complete crown preparation were performed using a polyether (Impregum Soft Heavy and Light body) and a vinyl polysiloxane (Perfectim Blue Velvet and Flexi-Velvet) in two consistencies, in one or two (without relief) steps.

Accuracy of the stone dies was accessed at a measuring microscope, using a metallic crown with perfect fit to the reference crown preparation.

Data were submitted to 2-way ANOVA and Tukey test (α=0.05).

Results.

The single-step technique resulted in slightly larger dies, while the 2-step technique without relief produced significantly smaller dies, when compared to the original stainless steel die.

Stone dies obtained from 2-step polyether impressions were significantly smaller when compared to dies obtained from 2-step vinyl polysiloxane impressions (Impregum 2-step: −290.94 ± 71.64 μm; Perfectim 2-step: −201.86 ± 28.58 μm).

No significant differences were observed in dies obtained from either polyether or vinyl polysiloxane with the single-step technique (Impregum single-step: 63.52 ± 16.60 μm; Perfectim single-step: 79.40 ± 14.11 μm).

Conclusion.

Higher discrepancies were detected for the 2-step impression technique without relief for the investigated materials.