A root treatment may require several visits to complete due to the complexity of the procedure. Many patients cannot appreciate what work is done as they cannot see any change within their mouths after the appointment. The series of diagrams below illustrates the cause and subsequent treatment of an infected pulp.
Once a healthy tooth becomes heavily decayed there is a chance that the nerve may be invaded by bacteria via holes in the dentin. The second diagram shows how the decay has gone through the enamel and dentin to reach the nerve where it produces inflammation and toothache..
Once the bacteria have reached the nerve the body starts to react by sending immune cells to the region to fight the bacteria. These cells travel around in the blood using the blood vessels as a natural motorway. The problem for our bodies is that blood must enter a tooth through a small hole at the tip of the root. This acts as a bottleneck which usually allows the bacteria to win the battle. The nerve tissue then starts to die from the point where the bacteria entered until all the pulp/ nerve tissue has died. The bacteria then colonise the inside of the tooth.
In order to treat the tooth, the dentist must cut an access hole in the top of the tooth. He will use the drill to do this. Once they have opened the tooth they will use a variety of instruments to clean the inside out. Small instruments the size of fine needles are passed down inside the root canals and used to file the inside walls which will be coated with infective bacteria. The dentist will rinse the inside out with disinfectants to kill bacteria which may hide in smaller canals off the side of the main chamber. Once they have completed this they will dry the canals with fine paper points.
The tooth then needs to be sealed to prevent any other bacteria entering the tooth from the mouth. The dentist will fill the tooth with gutta percha, this material is pink and rubber like in texture. The dentist will place these down inside the tooth and wedge them in to give a tight fit. The excess is then cut off with a hot instrument. Once this is done a normal filling is placed on top, usually a white filling in a front tooth.
One of the most difficult treatments performed by a dentist is a root treatment of a molar tooth. The procedure is difficult for many reasons but many patients expect it to be performed rapidly as they are unaware of the complicating factors.
Reasons for difficulty.

The tooth is situated near the back of the mouth making access difficult especially in those with small mouths. Many of the fine instruments are too long to fit directly into the tooth and have to be bent to make them fit.

Molar teeth have two or three roots and usually between three and four root canals though in some teeth there may be as many as six or seven. Each needs to be treated as any remaining bacteria may cause a painful re-infection of the tooth.

The nerve canals may also be narrow and twisted and difficult to get down. The instruments used are very fine and easily broken under these conditions.