How Do We Lose a Tooth?

A 38-year-old lady has a loose tooth (Fig.1 *) with root infection (<).  The tooth is so loose and painful that it needs to go (Fig.2,3), but there is no cavity.  The reason for loss of this tooth is most likely gum disease.  The surface of the crown is full of plaque (Fig.2 *), whereas tenacious tartar is found on the root surface (Fig.3).  She does not brush or floss that well. A striking feature of this tooth is that there is root resorption involving all of three roots (Fig.2 <).  Resorption means that roots have been eaten or dug out.  How?

Both cavity and gum disease are caused by bacteria (although by different species).  But gum disease is more involved by our body reaction.

Fig.4 represents a healthy root with smooth outline.  Our body recognizes it as a friend and does not attack it.  When we do not brush or floss our tooth and particularly the root portion for a while, the root surface is contaminated by bacteria (Fig.5).  Our body is so angry that it mounts strong immune responses, trying to get rid of the bad bacteria.  However, our body is not so smart.  It thinks the contaminated root an enemy.  The immune attacks (Fig.6 blue thunders) kill the bacteria and at the same time destroy the root (root resorption, Fig.6 rough surface) and surrounding bone (Fig.1<).  Although the crown may appear to be intact, the roots have thousands upon thousands of tiny wounds (holes, indentations).  This is how we lose our tooth or teeth. 

Xin Wei, DDS, PhD, MS 1st edition 06/22/2012, last revision 06/22/2012