Fig.1 Fig.3 Fig.5
Fig.2 Fig.4 Fig.6

Dental Education Lecture: Redo Molar Root Canal

It is not uncommon to redo molar root canal, because the anatomy of molar is very complicated.  It usually has three canals.  Sometimes there is an extra canal that is easily missed.  Besides, canals may be so tinny tiny that they are difficult to clean up.   Germs left behind cause reinfection.

In this lecture, we are going to show you three cases of molar root canal redo.

First, Ms. Xiao has severe abscess around a top molar in spite of the fact that the tooth has had root canal done.  X-ray shows that only one of three-canaled tooth (#3) has root canal fill (white arrowhead: <, Fig.1).  There is a large shadow (indicated by 4 red <) around the two unfilled root canals.  We inserted a rubber-like stick (2 black <) into the opening of the abscess.  The tip of the stick points to the shadow.  In all, we need to redo root canal for this molar.  Like front tooth root canal redo, we need to remove old filling and place a new, more solid, and slightly larger filling (white < in Fig.2).  Unlike front tooth root canal redo, we need to search for, clean up and fill the missed canals (black <).  X-ray in Fig.2 is taken 1.5 years after root canal redo.  The root tip shadow disappears, as compared to Fig.1.  By the way, crowns are placed for the teeth #3 and 4 after root canal.  These two teeth have big fillings before re-treatment (Fig.1).  The tooth #4 has a large cavity (C).

Mr. Jian is our second patient today.  He has pain in his bottom molar tooth once a week after root canal.  X-ray shows that root canal filling (black < in Fig.3) in 3 canals is short of root tip (white <).  We think that germs remaining in the root tip are culprit.  In fact, it is not so simple.  Root canal redo not only cleans up root tip of the three canals (Fig.4), but also finds an extra curvy canal (black <).  White < points to the root tip of the extra canal.  Pain goes away immediately after root canal redo.

Mrs. Yu is our last patient of root canal redo.  She does not have any pain at all, but one of her molars is severely broken down (< in Fig.5) and needs a crown.  Old root canal is not properly done.  In order to prevent potential re-infection after crown placement, we finish root canal redo (Fig.6). 

Xin Wei, DDS, PhD, MS 1st edition 05/13/2010, last revision 05/13/2010