Dental Education Lecture: When is a post needed?

A post is needed when the tooth is in very bad shape, i.e., badly broken down.  One day Susan bites something hard.  A front tooth is broken (Fig.1) with loss of a crown (inset).  The tooth has root canal done, as shown by pinkish material in the middle of the chipped tooth.  In order to put the crown back, we need to remove part of  the root canal filling material (Fig.2 arrowheads) and make a space (Fig.3 arrowheads).  Then a plastic pattern is being made to fit the root canal space on one end and fit the inner space of the crown on the other end (Fig.5).  The pattern is then sent to a lab to make a high quality metal cast post.  In the meanwhile, a temporary prefabricated post is cemented to the space created and the crown is cemented temporarily.  When she walks out of clinic, she looks something like that shown in Fig.4.

When the cast post is ready, we place and then permanently cement it (arrowhead in Fig.6) into the space and then permanently cement the existing crown (C) into the place.  Fig.4 shows the final result.  Since the cast post is custom-made, it fits the root canal space precisely and provides maximal stability for the crown.

Xin Wei, DDS, PhD, MS 1st edition 12/20/2009, last revision 03/28/2011