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

Area of Science:

• Dental Materials Science
• Prosthodontics
• Impression Techniques

Background:

• Accurate dental impressions are crucial for fabricating well-fitting prostheses.
• The choice of impression technique and material can influence the dimensional accuracy of the resulting stone dies.
• Understanding these factors is vital for predictable clinical outcomes in restorative dentistry.

Purpose of the Study:

• To compare the accuracy of stone dies produced by single-step and two-step double-mix impression techniques.
• To evaluate the dimensional stability of dies made from polyether and vinyl polysiloxane impression materials.
• To determine the influence of impression technique (single-step vs. two-step without relief) on die accuracy.

Main Methods:

• Polyether (Impregum) and vinyl polysiloxane (Perfectim) materials in two consistencies were used for impressions of a stainless steel die.
• Impressions were made using either a single-step or a two-step (without relief) technique.
• The dimensional accuracy of the resulting stone dies was measured using a measuring microscope and compared to the original die.

Main Results:

• The two-step impression technique without relief produced significantly smaller dies for both materials compared to the original die.
• Stone dies from two-step polyether impressions showed greater shrinkage than those from two-step vinyl polysiloxane impressions.
• No significant dimensional differences were found between single-step polyether and vinyl polysiloxane impressions.

Conclusions:

• The two-step impression technique without relief is associated with higher discrepancies and significant die shrinkage.
• The single-step impression technique offers better dimensional accuracy for both investigated materials.
• Material selection and impression technique significantly impact the accuracy of dies for complete crown preparations.