Dental Education Lecture: Why Do We Need to Remove Wisdom Tooth Early?

Wisdom tooth is also called the 3rd molar (3, Fig.1).  It is located behind the 2nd molar (2).  Every tooth has a crown and root(s).  Two arrows in Fig.1 indicate the root portion of 2nd molar.  Like every other tooth, the 3rd molar forms its crown first (3, Fig.1) and develops its root(s) later (Fig.2 and 3).  Its roots keep growing whether the tooth comes in (erupts into a normal position) or not . When the developing root encounters a hard tissue such as a nerve tube (two red lines in Fig.1), the tip bends before being calcified (hardened) (Fig.4 and 5).  If the surgeon is not fully aware of the bent root tip, it is most likely broken during extraction  (arrow in Fig.4; Fig.6).  Retrieving the broken root tip proves to be extremely difficult due to poor visibility. Green lines in Fig.6 indicates the socket.  We have to be careful using a small wedging instrument (blue in Fig7) to remove the tip (arrow in Fig.8).  Since the root tip is so close to the nerve tube (red lines in Fig.9) that the sharp instrument may poke into the tube by accident and injure the nerve inside.  You may lose sensation of the lower lip and all of bottom teeth on the same side.  It is a serious problem.

Fig.1 show a 3rd molar of 15 year old; Fig.2: 17 years old; Fig3: 21 years old; Fig.4: 31 years old.  As we get older, the root becomes longer and curvy.  If we have 3rd molars removed by the age of 21, we may not have problem of curvy root tip.  We have less chance of nerve injury.  We basically need to remove wisdom teeth before they create severe complications.

We have discussed the same issue (early extraction of wisdom teeth) from different aspect before.

Xin Wei, DDS, PhD, MS 1st edition 07/04/2009, last revision 08/30/2009