Impressions for Crowns and Bridges

Dr. Laura Tam
Authored By:
Dr. Laura Tam
Posted

Introduction

After a tooth has been shaped for a crown, a dental impression must now be taken to get an accurate record of this shaped tooth. Once the impression is taken, a mold of the shaped tooth is made and the crown can be built on this mold. The objective of this video is to show how a dental impression is taken for when you are having a crown done.

Preparation for Impression (Tissue Management).

A dental impression must record ALL of the prepared tooth surface. This cannot always be done if the gums are blocking the impression material from reaching the entire tooth. Therefore, gingival “retraction” cord is often used to temporarily move the gums out of the way. The healthier your gums are, the less the gums tend to get in the way. This is why your dentist will encourage you to maintain you oral hygiene home care around the tooth to be crowned.

When gingival retraction cord is needed, the procedure for tissue management is as follows.

  1. Ensure a dry and clean impression site with the use of cotton rolls, dri-angles and the saliva ejector as necessary.
  2. Place gingival retraction cord around the tooth.
  3. Wait 4 minutes.
  4. Wash and dry the impression site.

Impression.

The procedure for dental impression taking is as follows:

  1. Syringe impression material carefully around the tooth.
  2. Immediately seat the impression tray.
  3. Wait 5 minutes until the impression material has set.
  4. Remove the impression tray.
  5. Remove the gingival retraction cord.

Conclusion

A successful dental impression should accurately record all the features of a tooth preparation for a crown. An accurate mold of the tooth is essential for the fabrication of a well-fitting crown. A dental impression technique after careful tissue management has been shown using a silicone impression material.