Working times of elastomeric impression materials determined by dimensional accuracy

Area of Science:

• Dental Materials Science
• Polymer Chemistry

Background:

• Accurate dental impressions are crucial for fabricating restorations.
• Poly(vinyl siloxane) (PVS) materials are widely used for dental impressions.
• Understanding the precise working time of PVS materials is essential for clinical success.

Purpose of the Study:

• To accurately estimate the working times of five poly(vinyl siloxane) impression materials.
• To compare the estimated working times with manufacturer-provided recommendations.

Main Methods:

• A standard stainless steel model with known 3D landmark distances was used.
• Impressions were made using five PVS materials at successive time intervals.
• Dimensional accuracy of resulting stone dies was measured using a traveling microscope in x, y, and z axes.

Main Results:

• A time interval was considered within the working time if dimensional changes were not statistically significant compared to earlier intervals.
• Rejected time intervals also had absolute dimensions exceeding those from previous intervals.
• Estimated working times were consistently around 30 seconds longer than those stated by manufacturers.

Conclusions:

• The method provides a reliable estimation of PVS working times based on dimensional stability.
• Clinical working times for PVS impression materials may be underestimated by current manufacturer guidelines.
• Further investigation into the clinical implications of extended working times is warranted.