Fig.5                                  Fig.6



               Fig.2                      Fig.3                      Fig.7                                  Fig.8




Dental Education Lecture: Root Canal Therapy & Whitening

We talk about external and internal bleaching last lecture.  Our teeth become dark and dull when the nerve (pulp) is dead.  Reasons for dying nerve are cavity (Fig.1) and trauma (Fig.5).  The signs of dead nerve are abscess in root tip area (arrow in Fig.1) and bone infection shown by X-ray (black shadow: arrow in Fig.2; arrowheads in Fig.6).

In the first case (Fig.1-4), a 20 year-old lady starts braces in her country.  One of upper front teeth is discolored with an abscess.  Previous root canal filling (white in the middle of the tooth, Fig.2) is not solid or thick enough with space next to it (arrowhead).  We redo root canal therapy (thicker filling with no space; arrowhead in Fig.3).  We intentionally leave a large space (red *) in the crown end for internal bleaching.  We also remove old filling and fill with a temporary filling.  The latter is removed before we do internal and external bleaching.  Final result is shown in Fig.4.  

A 40 year old motorcyclist lost several teeth in an accident several years ago (Fig.5).  The 2 remaining teeth look pretty dark. He comes to my office for an upper partial denture.  Due to color discrepancy against neighboring and opposing teeth, we recommend root canal therapy and internal bleaching for these 2 teeth and external bleaching for whole mouth.  After treatment, the shade of these 2 teeth improve.  We use the two same shade guides on photo taking for unbiased comparison (Fig.5 and 7).  After internal bleaching, we fill the space with white material as indicated by 2 double arrows in Fig.8, which further improve whitening.  Final result for the second case is shown in Fig.9 after we deliver a partial denture.  He is also pleased with functioning denture.  He eats better.

Successful root canal therapy resolves abscess.  There is no redness in the root tip area in Fig.4.  Compare it with the same area pointed by arrow in Fig.1.  Bone infection is also improved after root canal therapy.  Black shadows pointed by arrowheads in Fig.8 are either reduced in size or the density increases as compared to those in Fig.6.  You can look at more cases of tooth whitening or study how to do internal bleaching at home.

Xin Wei, DDS, PhD, MS 1st edition 02/01/2009, last revision 02/11/2009