Dental Education Lecture: Preformed Post
Hector has had molar root canal (Fig.1:<) without a crown (cap) for a while. One day a large portion of the tooth is chipped (*). The remaining filling (F) is too small to hold a cap. So we need to make a preformed post first.
To do so, we remove part of old filling from the tooth (Fig.2: *) and remove part of root canal filling to create a space (<) so that a post can be inserted into the space and glued there (Fig.3: <). The part of the post that sticks outside the space (red outline) can be used to build up a new large filling (F: black outline, so-called core). The new strong filling can hold the crown (cap: C in Fig.4) in place.
If Hector's chip is more severe (almost all of the crown is gone), a cast post is required. Cast post is stronger, but more complicated. Two appointments are needed. By contrast, preformed post just needs one appointment.
If chip or crack extends to the root, the tooth may not be saved. Therefore, after molar root canal, return to office to place a cap as soon as possible. Do not take a chance.
Xin Wei, DDS, PhD, MS 1st edition 06/01/2010, last revision 05/17/2011