Jim Sarji, DDS of Advanced Gentle Dentistry of Park Slope explains a common procedure.

This is actually a common procedure and we decided to write this article to explain the process to our patients . This often occurs when a tooth has had a previous root canal which has failed. When the first root canal was done a crown was placed over the tooth on the part that was not decayed with a post being inserted into the tooth so that the crown can be attached properly. Now that the root canal has failed and needs to be retreated the dentist is presented with a choice as to how he should progress.

The dentist has two choices

First Option — Ideally the dentist will remove the crown before he drills the access cavity, however this is not always possible. There may be the possibility that he will damage the existing structure of the tooth.

Second Option — If the dentist determines that the crown will not come off then an access cavity must be drilled. In most cases the crown will be replaced although the tooth structure may have changed so it will not be possible to use it again. If the dentist has had to drill through it then this may weaken the crown.

In most instances a new crown is needed as the structure and integrity of the crown will have been changed or may be compromised. The root canal could become re-infected very easily if the previous crown is used. It is almost always advisable to remove the crown therefore protecting the integrity of the crowns and allowing the root canal procedure to take place;

For a dentist to remove a crown in a manner that it remains fully intact and unscathed can be very difficult if not impossible. During the attempt it’s still possible that the crown will be damaged or worse yet the tooth damaged too and maybe significantly.

Other reason for a crown failing is because of tooth decay at the edge of the crown where it meets the gumline. The crown obviously does not decay but the underlying tooth gets decayed. In a situation like this when it this happens, the decay quickly spreads underneath the crown.

If the decay is significant there may be very little tooth structure left under the crown before the pulp (nerve) becomes destroyed by the decay. In a case like this a new crown will not fix the tooth and a root canal will be needed along with the new crown assuming we can actually save the existing tooth structure. When a dentist places a new crown on a tooth that already has had a crown it will take more work and will be more difficult to do that the first crown. This is due to the fact that the margins or edges of the crown will need to be deeper in order to cover up the area where the decay was removed after the old crown was taken off. This is often a complicated procedure but we have a lot of experience in dealing with these.

Crown are long lasting cosmetic restorations that for the most part will give a cosmetic appearance and perform a fuction but they will eventually wear out. Decay under the crown causes the crown to eventually fail. It is important that a dentist can detect early signs of decay at the edge of a crown. It takes a high degree of artistic skill to detect early decay on the edges of a crown. It must be replaced quickly in order to prevent a root canal or infection. Ask us when you come to see us about how you can take more care of your crowns.

Root Canal Re-treatment — What is the process

Many a time a root canal will fail and a patient tooth may not heal as was expected and after the first root canal treatment. This can happen for a number of different reasons and in such cases the dentist will have to open the tooth again and readdress the infection. It may have failed for the following reasons:

• The root canals were to narrow and caused problems for the endodontist or dentist performing the initial procedure.
• The patient had a complicated pattern of root canal (imagine the roots of a plant) and some parts were undetected in the initial procedure.
• While the replacement of the crown or restoration being used in the initial treatment was delayed the interior part of the tooth became infected which resulted in reinfection of the root canals.
• The seal that was made around the restoration (crown) or filling was not adequate and the tooth became recontaminated.

The worrying part is that not all of these will cause symptoms but they can still lie dormant and they can cause serious infection. In a dental x-ray this usually appears as a blackened area at the bottom of the affected root. There are other factors also that could cause a successful endodontic treatment to go wrong.

Some of these root canal issues that could cause a need for further root canal treatment are as follows:

• New decay around the tooth could expose the inside of the root canal filling to bacteria. this could cause a whole new infection to the root canals.
• A crown that has become loose, or broken could expose the tooth structure and cause decay resulting in a new infection.
• The root becomes fractured or the actual tooth becomes fractured.

What is the process during pre-treatment for a root canal.

It is important to review all options before undergoing root canal re-treatment and weigh up the benefits and the alternatives. It is usually always possible to re-treat the tooth but Dr Sarji will have to re-open the tooth. Dr Sarji will create a small hole into the biting surface of the tooth which will allow him access to the root canal. In the majority of cases the restorative materials will be removed and the root canals will be cleaned and carefully examined using microscope technology and high intensity illumination. Dr Saji will search for root canals and look for unusual canals that will require extra treatment. Once Dr Sarji has cleaned and shaped the canals they will be resealed with ‘gutta percha’ and he will create a dental dam around the area so as not to get any infection into the newly cleaned root canals. Once the canals have been sealed he will add the restoration ‘crown’ and the will make sure that the tooth and surrounding structure is completely sealed. The tooth is now sealed and will function properly with the new crown.

Is root canal re-treatment the best alternative and do I have any other options?

It is always best to save a tooth where possible. After a root canal re-treatment teeth can fiction properly for many years, even for the rest of your life. These days endodontic technology is changing constantly and the technology that was available when you had your first procedure may be different from the technology now.

If Dr Sarji cannot re-treat the root canals using non-surgical treatment then endodontic treatment may have to be done. Here he will make a cut in the gums to allow access to the root.

The last alternative to re-treatment or a failed endodontic procedure is the complete extraction of the tooth. Dr Sarji could replace this with an implant, a bridge or possibly a removable partial denture. Any of these procedures will restore a patients chewing ability, their ability to smile and will prevent neighboring teeth from shifting. However these procedures can be costly. They also require Dr Sarji to perform procedures on neighboring teeth. This can be a costly experience and time consuming — a dental implant may work out to be cheaper in the long run.

Jim Sarji, DDS is a dentist in Park Slopeand thepractice owner of Advanced Gentle Dentistry of Park Slope. The practice was started 20 years ago in Park Slope and offers teeth cleanings, root canal treatments, dental fillings, dental crowns, dental implants, emergency dentistry, dental bridges, emergency dentistry and all forms ofcosmetic and general dentistry. The practice is open Monday to Saturday and accepts most insurances. If you are looking for an emergency dentist in Park Slope and you have a dental emergency the call us on 718-499-2375.