Accuracy of second pour casts using dual-arch impressions

Area of Science:

• Dental Materials Science
• Prosthodontics
• Impression Techniques

Background:

• Accurate dental impressions are crucial for fabricating prosthetics.
• Addition silicone materials are widely used for their accuracy and hydrophilicity.
• The choice of impression tray can influence the dimensional stability of the cast.

Purpose of the Study:

• To compare the accuracy of second pours from addition silicone impressions.
• To evaluate three types of impression trays: custom acrylic resin complete-arch, metal dual-arch, and plastic dual-arch trays.
• To determine if tray type affects the dimensional accuracy of gypsum casts.

Main Methods:

• Thirty impressions were made on a typodont using the three tray types (10 per group).
• Custom metal dies with reference marks were used to measure mesial-distal, buccal-lingual, occlusal-gingival, and inter-tooth dimensions.
• Gypsum casts were poured twice, with the second pour evaluated 24 hours after the initial impression.

Main Results:

• No statistically significant differences in accuracy were found among the three tray types for most measurements.
• The metal dual-arch tray demonstrated statistically significant higher accuracy in the inter-tooth measurements compared to the other trays.
• All trays produced acceptable accuracy for the second pour of addition silicone impressions.

Conclusions:

• The type of impression tray used has a minimal impact on the overall accuracy of second pours with addition silicone materials.
• Metal dual-arch trays offer an advantage for capturing precise inter-tooth distances in the second pour.
• Clinicians can be confident in using various tray types for routine impressions, with metal dual-arch trays preferred for critical inter-tooth measurements.