Fractured teeth represent a silent disease.  Pets do not grab their cell phones and call their dentist when this happens – people do.  As discussed, pets mask their discomfort. 

In the case of fractured teeth with pulp (nerve exposure) the tooth is painful for a few days then as the pulp dies the acute pain subsides.  This give the pet owner the false sense that everything is fine.  Once the pulp is exposed the infection progresses down the canal to the tip of the tooth root.  When the tip of the tooth root becomes infected the pet simply avoids using the tooth.  

 

With upper fourth premolars (the large pointed tooth is the back of the mouth) heavy biofilm accumulation is a clue that the tooth hurts, especially when noted only on one side.   The bacteria always win if left untreated.

Treatment is either removal of the fractured tooth or root canal therapy, if sufficient tooth remains to warrant this procedure.  Root canal therapy is very successful in companion animals given anatomically, pets teeth are better suited for this procedure.  Treated teeth most always last the pet's life...unless, of course, the pet is an aggressive chewer and enjoys fracturing its teeth.