Fig.1 Fig.3
Fig.2 Fig.4

Dental Education Lecture: Floss and Crown

Mrs. Yang loves to floss, but the floss gets caught and torn when she flosses a tooth with crown (C in Fig.1).  X-ray shows that there is a pretty big step underneath the crown.  The edge is pretty sharp and rough (Fig.1 magnification).  Food and germs are easily trapped there.  New cavity and gum diseases have high tendency to develop there. Therefore, the crown needs to be replaced. 

She also complains of tooth sensitivity when she flosses there.  Look at the bottom of the tooth (Fig.2).  You may notice shadow at root tip (arrowheads), suggesting infection.  Although root canal (R) has been done before, we need to redo it to get rid of re-infection.

After redoing root canal, a new crown is placed (Fig.3).  There is smooth transition from the crown to our natural tooth (arrowhead).  Mrs. Yang has no difficulty in flossing.  The floss is not torn any more.

Two years after root canal redone (by Dr. John Welch), the root tip shadow is gone (Fig.4).  Tooth sensitivity also disappears.  Mrs. Yang enjoys flossing even more.

Xin Wei, DDS, PhD, MS 1st edition 04/19/2010, last revision 04/22/2010