Dental Education Lecture: Multi-step Bleaching

Single tooth discoloration is not so appealing (Fig.1).  It is also difficult to fix.  This young lady hurt her lower front tooth in junior high.  In spite of root canal (treatment), the tooth has been discolored since.  She wants to have mouth make-over: first, whitening the tooth and then, having braces.

Before whitening, we have to compare the shade of the discolored tooth (A3.5) and the rest of the teeth (B1).  A3.5 and B1 are shade guides; we re-use them to judge whether we achieve satisfactory results when whitening is done (Fig.8).

The old root canal is apparently not well done (Fig.5): the filling (R, white)) does not reach the root tip (compare >> vs. >); there is a gap between the filling and canal itself.  These may cause infection in the future.  So we decide to redo the root canal (Fig.6).  The new filling (R in Fig.6) is more solid and reaches the root tip.  Two arrowheads in Fig.6 point to defects which happens after injury several years ago (so-called internal resorption).  The root canal filling should remain undisturbed for a couple of days with a temporary (T) filling on the top.  Then the dentist remove the temporary filling and a little more of root canal filling (R in Fig.7).  The latter creates plenty of space for internal bleaching.  

Fig.3 shows the change immediately after redoing root canal. The doctor uses a lot of bleach to kill germs inside the root canal without leaking into the mouth.  The bleach also whitens the tooth to our benefit.  But the darkness may rebound so we need to use a special agent to further whiten the tooth.  We let the patient do it at home for about two weeks.

Fig.4 show the result after take-home bleaching.  Fig.8 shows the final results after in office bleaching and filling the hole (arrowheads in Fig.7) with white filling.

Xin Wei, DDS, PhD, MS 1st edition 08/30/2009, last revision 09/08/2009