|Endodontics – Root Canal Therapy
by Dr.R.D. Skinner
Causes of death of the pulp in teeth
When a tooth is damaged, the pulp (i.e., the nerve) reacts to the injury by becoming inflamed. Inflammation is characterised by increased blood pressure, swelling, redness and pain. As the pulp of the tooth is confined by the dentine anything more than mild irritation, leads to the death of the pulp. Irritation can be from many sources. Heavy biting forces over time as with bruxism can lead to the death of the tooth. Also exposed dentinal tubules from tooth brush abrasion can in time lead to the death of the pulp. Caries (tooth decay) is the most common cause of dead teeth, when bacteria and their toxins invade the pulp, but also cracks in teeth can lead to irreversible pulpitis as well.
Determination of the need for Endodontics
Careful examination and tests confirm the diagnosis of irreversible pulpitis when the pulp in the tooth is dying or is already dead. At this point there are only two treatment options available. They are extraction of the tooth or endodontic therapy. Careful assessment will determine if the tooth can be endodonticly treated as cracks, root fractures and very extensive caries make the tooth unrestorable. If the tooth is lost, it can often be replaced with a bridge or implant. All posterior (back) teeth that are endodonticly treated should be protected with a crown.
Aims of Endodontic Treatment
The aim of endodontic treatment is to remove all the infected material from the pulp chamber and root canal system and fill the root canal system with an inert filling material. Effectively this creates a clean wound at the end of the roots where the blood supply in the bone around the tooth can effect healing. This is a simple concept but in reality can be difficult and challenging. Even so endodontics has a success rate of about 95%.
How a tooth is Root Treated
Often the first step is to replace the filling in the tooth, removing the decay and placing a restoration that seals the tooth stopping re-infection by bacteria. A pre-treatment x-ray is often taken at this time.
The tooth is isolated by placing a rubber dam over the tooth that forms a sealed barrier between the mouth and the tooth being treated. For those with a latex allergy, there is vinyl dam material available.
The pulp chamber is accessed from the top of the tooth so that instruments can be used to clean and shape the canal system in addition to frequent irrigation. It can sometimes be very difficult to find and negotiate all the canals in a tooth, in recent years there have been many advances in endodontics. We now have nickel titanium files and new filling materials. By far the most important advancement in endodontics today is the use of operating microscopes. Virtually all endodontic specialists use an operating microscope when performing root canal therapy. At my practice both surgeries have an operating microscope. I have been using an operating microscope for most dental procedures since the year 2000.
At the first treatment appointment the canals are shaped and cleaned and disinfected and an x-ray taken to establish the correct length. The tooth is then dressed with a cortico-steriod antibiotic paste and sealed to prevent reinfection.
After a week or two, the procedure is repeated, and if the canals are clean and the tooth has been symptomless, then the root filling is placed, checking with an x-ray that the filling goes to the end of the root.
If the tooth should still be infected, it is cleaned and dressed and left for a longer period. Redressing the tooth will continue until all has settled and the tooth will eventually be filled.
It is interesting to note that people in the United States of America dread root canal therapy as being a long and painful process. In Australia the use of cortico-steriod antibiotic paste ensures that most patients have little or no pain during or after treatment. At the end of treatment a final x-ray is taken to ensure that the root canals have been completely filled.
The Post and Crown
Posterior teeth that have been root filled are often weak and heavily restored. They require protection, and that protection usually consists of a carbon fibre post and Glass Ionomer or composite core material covered by a porcelain fused to precious metal crown. To see how we prepare teeth please go to the Crown and Bridge page.
The copyright for the above article is owned by Dr.R.D Skinner.
For all your Endodontic enquiries please call
(03) 9662 1505.