Which impression material is preferred for crown preparation when using an elastomer in a custom tray?

Vinyl polysiloxane is the preferred impression material for crown preparations when using an elastomer in a custom tray because it offers several advantageous properties. First, it has excellent dimensional stability, which is crucial for ensuring that the mold remains accurate over time, especially during the transfer from the mouth to the lab. This material also provides good tear resistance, allowing for the detailed capture of the preparation without distorting the impression upon removal.

Another significant benefit of vinyl polysiloxane is its ability to capture fine details, making it ideal for crown and bridge procedures. This precision is vital when constructing restorations that fit well and function properly. Additionally, vinyl polysiloxane has favorable working and setting times, offering dental practitioners enough time to manipulate it without compromising the efficiency of the procedure.

While other materials like polyether and condensation silicone have their own merits, they may not match the overall performance characteristics that vinyl polysiloxane provides in the context of crown preparations. Polyether, for instance, while providing good accuracy, can be more rigid and less forgiving during removal, potentially causing distortion. Thiokol or mercaptan rubber has largely fallen out of favor due to their more complex handling and less desirable properties compared to modern alternatives. Thus, for crown