Why Do So Many Impressions Need To Be Taken For A Crown?

If you've never had a crown placed on a tooth before, you may be surprised at just how many impressions need to be taken before the crown is placed. While getting an impression can be a little awkward, each one is vital to the success of the procedure. Here are some of the impressions you'll need to have done and why they will help your dentist.

Provisional Impression

This is the very first impression you'll have taken at your appointment, before the dentist shapes down any enamel. The provisional, or temporary impression, is used to make a temporary crown. Temporary crowns are usually made from acrylic and will last you a couple of weeks until your permanent crown can be placed. Once the impression has been taken, the dental assistant will set it aside until the doctor is ready for him or her to insert acrylic into it and shape it for placement. There are many benefits of a provisional:

• It prevents adjacent teeth from shifting into space where enamel has been removed
• It makes the patient more comfortable, as he or she won't have to bite down on a enamel that has been shaved down
• It protects the prepared site from saliva, food debris, and infection

Bite Registration and Opposing Impression

The bite registration and opposing impression are taken next. The bite registration is usually taking with a syringe rather than a tray. The dentist will have you bite down on impression material which will capture the upper and lower jaws' occlusion.

The opposing impression is taken to show the teeth of the opposite jaw. For instance, if you are getting a crown placed on the maxillary arch, then the opposing impression would be taken for the mandibular arch. While it may seem strange for the dentist to take an impression of teeth that aren't going to be worked on, it is necessary to have these impressions as they show dental lab technicians how a patient bites down. Without these impressions, the crown may feel funny or sit too high in a patient's mouth, making it uncomfortable to chew.

Master Impression

The master impression is taken once the dentist has used the high-speed hand-piece to shape the tooth. First, the dental assistant will pass the dentist a light-body impression material with a syringe. The light-body material can capture very accurate details and margins of the tooth.

While the dentist is placing the light-body material, the assistant will fill up a tray with heavy-body impression material. The heavy body material has a different viscosity and doesn't capture as many details as the light-body material. However, it will help to hold the master impression together.

The light-body and heavy-body materials are usually different colors as this helps the dental lab certify that all the necessary details have been taken in the impression. Once the master impression is taken, the dentist will send it to a dental lab where your final crown—usually made of porcelain—will be made and sent back to you for your recall appointment.

As you can see, each impression serves its purpose in the fabrication of your crown. For more details on your crown placement, contact a dentist in your local area or visit a site like http://www.accentdentalnwi.com/.