Dental Education Lecture: Root Tip Infection 

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In last lecture, we talk about a few features of nerve (pulp) infection.  If infection is confined to the nerve, you cannot tell which tooth bothers you.  You have a bad tooth in the upper jaw, but you may feel that pain is from the lower jaw.  Diagnosis is critical.  You should allow the dentist to examine your teeth in an all-around manner.  He may take out a wrong tooth.  When infection spreads outside the root tip, your tooth becomes "high" and tender.  You cannot bite down.  The good thing is that you do not need a doctor for diagnosis.  You know clearly which tooth is a trouble maker.  In this lecture, we discuss two types of root tip infection, i.e., abscess.

In last lecture, we use a big red circle to represent root tip infection.  In reality, you can see a red bump associated with root tip infection (arrow in Fig.1 in this lecture).  The red bump is an abscess.  Sometime yellowish pus comes out the abscess.  It tastes like raw fish.   The affected tooth has a big cavity (Fig.1).  The previous dentist fabricated a temporary crown (*, Fig.2) without finishing root canal therapy.  A week after root canal therapy (Fig.3), the abscess almost completely disappeared (arrow, Fig.4).  As long as infected nerve is completely removed, cleaned up and packed tightly, root tip infection will resolve by itself.  In this case, root canal therapy is fairly well done.  You can see that the main canal is solidly filled.  Some of filling material is pushed into a side canal.  For description of main vs. side canals, please read last lecture.

Sometimes root tip abscess is more severe, as shown in Fig.5 and 6.  A swelling is noticeable on the right side of the face, outside the nose (Fig.5).  The face looks more asymmetric when the patient tilts her chin up (Fig.6).  As discussed in lecture Immediate Extraction, veins in facial region have no valves.  Blood and infection in our face can travel upward to our eye and brain, consequence of which is very bad.  When we lift the upper lip, a chipped canine tooth is jump at our eyes.  Yellowish pus was flowing out of the root stump (Fig.7).  Since this infection is associated with canine, it is called canine space infection.  Before antibiotic discovery, this type of infection was deadly.  We could have chosen immediate extraction to resolve this severe root tip infection.  However, since the canine tooth is one of the most important teeth in our mouth with the longest root, we did immediate root canal therapy supplemented with oral antibiotic. The infection subsided quickly and the tooth was saved.  The appropriate subsequent treatment for this case is discussed in Fig.9 of lecture Tooth Repair.

Xin Wei, DDS, PhD, MS 1st edition 1/30/2009, last revision 06/11/2009