Finish Root Canal without Damage to Crown
Mrs. Wong in her sixties has had a nice gold crown for 20 years (C in Fig.1). Suddenly the nerves inside the tooth with the crown get infection. She cannot drink or eat. The tooth is sensitive to cold or hot. It is also tender to touch, not to mention chewing. The teeth on the other side of her mouth are even worse. She cannot chew with them for a long time.
Anyway, the tooth with the crown needs root canal. To do root canal, a hole needs to be drilled in the middle of the crown (H in Fig.2) to get out infected, painful nerves. The integrity of the crown is lost. It may exert bad psychological pain on Mrs. Wong. Sometimes it is very difficult to find nerves inside the tooth through the hole.
If the crown is not good, i.e., broken, it should be cut out before root canal. A new crown will be made after root canal.
Luckily we figure out a way to remove the crown without any damage to it (Fig.3). In fact, Mrs. Wong's nerves are tinny tiny and very complicated. There are four of them (1-4 in Fig.3). Two of them (3,4) fuse on the bottom (arrowhead). It takes two appointment to finish root canal. With the crown off, removal of nerves is not so hard. On the second appointment, Mrs. Wong reports that the pain is completely gone. She can eat and drink normally. When root canal is finished, the crown is cemented back in place (Fig.4: C). Mrs. Wong can eat and drink normally after treatment. Hopefully, she can use the crown for another 20 years.
Xin Wei, DDS, PhD, MS 1st edition 08/17/2011, last revision 08/22/2011