Accuracy of casts generated from dual-arch impressions

Area of Science:

• Dentistry
• Dental Materials Science
• Prosthodontics

Background:

• Dual-arch trays are commonly used for simultaneous dental impressions of prepared and opposing teeth.
• Concerns exist among dentists regarding the accuracy of casts produced using dual-arch impression techniques.

Purpose of the Study:

• To compare the accuracy of stone casts generated from two types of dual-arch impression tray and material combinations.
• To evaluate the dimensional accuracy of dies produced using plastic versus metal trays and polyether versus vinyl polysiloxane impression materials.

Main Methods:

• Prepared a maxillary first molar on a dentoform for a full-coverage gold crown.
• Made ten impressions using plastic or metal trays with either polyether or vinyl polysiloxane impression materials.
• Cast impressions in improved dental stone and measured the buccolingual dimension of the resulting die, comparing it to the prepared tooth as a control.

Main Results:

• The plastic/vinyl polysiloxane combination yielded the largest die (10.673 mm), while the metal/vinyl polysiloxane combination produced the smallest die (10.472 mm).
• A significant difference in die dimension was observed between tray types (plastic vs. metal).
• No significant difference in die dimension was found between the impression materials (polyether vs. vinyl polysiloxane).

Conclusions:

• Metal trays resulted in dies smaller than the prepared tooth.
• Plastic trays produced dies that were larger than the prepared tooth.
• Tray material type is a critical factor influencing the dimensional accuracy of dental casts made with dual-arch impression techniques.