In which instance is irreversible hydrocolloid not suitable?

Irreversible hydrocolloid is a material commonly used for making impressions in dentistry, primarily due to its easy manipulation and ability to capture fine details. However, there are specific situations where it may not be the most suitable choice.

For provisional crown and bridge impressions, while irreversible hydrocolloid can technically be used, it may not provide the accuracy and stability required for definitive provisional restorations because these require a more stable and dimensionally accurate material to ensure a proper fit and function.

In the case of study models, irreversible hydrocolloid is generally an acceptable material since the primary need is to create a replica of the oral structures for study purposes. However, it may not serve well for cases where high fidelity and detail are crucial.

Final impressions, particularly when a chamfer margin is involved, usually require more precise materials such as polysiloxanes or polyethers. These materials offer superior dimensional stability and detail reproduction compared to irreversible hydrocolloids, which can distort or lose detail.

Thus, while irreversible hydrocolloid can technically be used for all the situations mentioned, it is the least suitable for scenarios where high accuracy is necessary, such as for final impressions with detailed margins. The best practice would be to use materials designed for those specific applications to