Root Canal Therapy: Take Two! Guest Post by Neha Shah, D.M.D.

Superb endodontist (and awesome human being) Neha Shah DMD writes our latest guest post and explains a pervasive mystery in dental treatment:

Many people are surprised when they hear that they need a root canal on a tooth that has already been previously root canal treated. Wasn't the entire purpose of doing the root canal to not to ever feel pain again in the tooth? Commonly I hear from patients, “All the nerves are out, so how come this tooth is hurting?” The most common misconception from patients is that when a tooth has had root canal treatment, it is as if the procedure has created a force around it so strong that not even kryptonite can penetrate it. However, this is far from reality.

When a tooth has been treated for a root canal, it is in essence "rendered dead". A tooth that has had root canal therapy is essentially void of the living pulp tissue at the core of the tooth and therefore not able to respond to temperature stimulation. So the tooth is not able to tell you if something is hot or cold. However, it is still able to perform other functions of a mature, vital tooth because it still has the basic structures of a natural tooth namely enamel, dentin and cementum. This is what renders it susceptible to all of the threats that a vital healthy tooth is susceptible to. In fact, some may argue that a root canal treated tooth is slightly more vulnerable than a healthy, vital tooth. This means a tooth that has been treated for a root
canal is susceptible to decay (cavity), fracture, and infection just like any other tooth in the mouth. So it is imperative that a root canal treated tooth is properly cared for and protected.

One of the biggest threats to our teeth is BACTERIA. Our teeth are constantly bathed in saliva that have bacteria. These bacteria which are naturally present in our oral cavity are opportunists and when the environment is ripe will attack the basic structures of the tooth. So at every opportunity, at every level from performing the root canal, to sealing the root canal, to sealing the tooth, this basic goal of keeping the bacteria out is practiced by dental health provider and encouraged to patient.

So what is causing that root canal treated tooth to hurt? Infection and Inflammation. For every infection there is associated symptomatic (painful) or asymptomatic (no pain) inflammation. The primary reason why root canal needs to be redone is for what we term "coronal leakage" ("coronal" meaning "crown"). What this essentially means is that bacteria have penetrated through and into a previously disinfected root canal system. Other less common factors that lead to retreatment is a previously untreated canal, undetected root fracture, or persistent infections within the root canal system due to complex anatomy or extraradicular infections. Regardless, the common thread that runs through these causes of failures is again bacteria, "bugs", or microorganisms.

In a nutshell, the etiology is bacteria and the treatment is disinfection. This is precisely the primary goal of retreatment therapy. During retreatment any existing restorations or posts leading to the root canal system have to be disassembled. The root filling material has to be removed and the entire root canal system has to be disinfected. Once the disinfection process has been completed which usually is completed in two or more visits, new root filling material is then placed and once again an opportunity has been set to seal the tooth properly and restore it to full function. In essence, retreatment is like giving the tooth 2nd life. In some
ways you can use the analogy of the life lines from “Who Want’s to be a Millionaire?” #1 life line for a tooth is root canal therapy. #2 life line is your endodontist when (s)he performs retreatment procedure due to reinfection of the initial root canal therapy and your last life line is your endodontist when (s)he performs an apicoectomy on a tooth that has already had root canal therapy more than once. Your million dollar is when you save your self of the aggravation of extracting the tooth and finding a way to replace it with a prosthesis.

To illustrate, here is a case that has failed for many of the reasons mentioned above:

*Coronal leakage
*Missed canal
*Separated files
*Persistent infection due to anatomy
*Inadequate initial debridement

 

 

Once the etiologies were identified, all of them needed to be addressed to set the stage for success.

For the above case, the tooth’s prior root canal had to be disassembled through a permanent crown. Goal of the retreatment for this case was to remove post, remove separated files, locate additional canal, remove existing root filling and fully debride and disinfect root canal system and medicate to create an environment for healing. The last two x-rays show the finished treatment.

You may realize that the tooth behind the one that was treated is in a similar predicament. It too will require retreatment for long term success.

Root canal therapy is a highly predictable, highly successful procedure when the tooth is treated and restored properly. Like any medical/dental procedure, the responsibility of performing the procedure properly lies in the hands of the health care provider but the care and maintenance after the procedure is shared by the patient and the provider. Remember, if at first you don’t succeed, try, try again.

(Dr. Shah practices at TEC Endodontics: http://www.tecendo.com/) 

Comments

[andy]

Root canal therapy is a highly predictable, highly successful procedure when the tooth is treated and restored properly. but care and maintenance of our teeth is very essential. great entry. great advice. keep writing.

[London Hypnotherapy]

Intreseting read. Thank you

[Vlad Tismensky, DDS]

Nice work Dr. Shah! Hoping to see the periapical area resolving with time.

[Williams Schermer]

Root canal is one of the most important breakthroughs in dentistry, as it relives damaged teeth. This is a great read here. This post definitely raises awareness and busted the myths related to root canal.

[andy]

Nice post regarding the problem faced by most of us related to root canals, and this post is very helpful. This is a great innovation. I think more people will opt for root canal procedure because having root canals discolors the teeth.

[andy]

To determine whether your tooth needs root canal treatment, your dentist will often place hot or cold substances against the tooth. The purpose is to see if it is more or less sensitive than a normal tooth. He or she will examine the tissues around the tooth and gently tap on the tooth to test for symptoms.