What is a Post & Core and how to scan it – Part #1

What is a Post & Core and How to Scan It - Part 1Dental labs handle ‘Post & Core’ cases from time to time. These days, clinics are requesting zirconia-fabricated cases for aesthetic reasons.




Image Source : http://www.speareducation.com/spear-review/2014/05/restoring-discolored-endodontically-treated-teeth-case-7

It is hard to get aesthetically satisfactory ‘Post & Core’ results with metal because the metal can be seen through the prosthesis.




Image Source : https://www.infodentis.com/post-and-core/main-concepts.php

CAD/CAM must be used to make the ‘Post & Core’ with zirconia. However, it is not easy to scan the post area with general stone model scanning methods because the model contains a deep hole, making it difficult to scan the geometry (the arrow point in the picture).



Due to the scanning difficulty, several methods to scan ‘Post & Core’ have been created to manufacture the case in zirconia.

The first one is scanning the impression. Scanning the post area is easy because it is a protruding shape on the impression.
However, the margin and core area are hidden by the post, making it difficult to scan them. Also, it is not easy to scan the adjacent teeth or the antagonist tooth (particularly at the arrow point in the picture).

Therefore, only scanning the impression is not a satisfactory solution.



A second method is to use a pin to mimic the shape of the post. The process is similar to scanning an implant scanbody, which merges the scan data with the pin library data once the pin is placed in the hole. The method’s basic assumption is that the hole shape is similar to the pin. However, there is a relatively big gap between the hole and the pin so the results are not accurate in many cases.

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The final method is to use wax-up functionality in CAD with scan data of the mockup which is made with pattern resin. This can be more accurate but it is time consuming and requires manual work.


Image Source : https://openi.nlm.nih.gov/detailedresult.php?img=PMC3339019_JCD-15-191-g004&req=4

The ‘Post & Core’ functionality in colLab 2017 has been designed to utilize the advantages of both impression scanning and stone model scanning. The best results are attained in the shortest amount of time by combining an impression scan of the post with a model scan of the core, antagonist, and margins.


How to use the ‘Post & Core’ functionality in colLab 2017:

Set the parameters for a ‘Post & Core’ case. In this example, we will make ‘Post & Core’ for tooth 25.

Select veneer type for tooth 25.

Some people ask why veneer type is used for ‘Post & Core’ cases. There is no separate type for ‘Post & Core’ so veneer was chosen to include the Post & Core settings.


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