Impression For Crown and Bridge

[Dr. Hussein Almaliky]

Impression For Crown and Bridge

Impression: it is the negative reproduction or negative likeness of the oral soft and hard tissue and their relationship. Impression can be made by placing fluid or semi fluid material inside the patient mouth and wait until it set's then removing it. From the impression, a positive reproduction or cast is made.

Requirements of a good impression:
1. It should be an exact duplication of the prepared tooth, including all the preparation and enough uncut tooth surfaces beyond the preparation to allow the dentist or technician to be certain the configuration of the finish line.
2. Other teeth and tissue adjacent to the prepared tooth must be accurately reproduced to permit accurate articulation of the cast and to allow a proper contouring of the restoration.
3. The impression of the preparation must be bubble-free, especially in the area of finishing line.

Requirements of the impression material:
1. It must become elastic after placement in the mouth because it must be withdrawn from the undercut that usually exists on the external tooth surface adjacent to the preparation. So, it should be able to return to original shape after removal.
2. It must have an adequate strength to resist tearing during its removal from the mouth.
3. It must have adequate dimensional stability and reproduction of details, so we can get the exact imprint of the prepared and unprepared teeth.
4. It must have a good handling and setting property that meet the dental requirement and it should be free of toxic or irritating compounds.

Download the lecture in Microsoft Word here:

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[nicholesgibs]

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