In dentistry, we often hear patient’s frustrations expressed (understandably) something along the lines of: “Doc, my tooth was fine before you worked on it and now I need a root canal IN ADDITION to what you did?! Why didn’t you tell me I would need a root canal?”
Even in today’s advancing digital dental world, the need for a root canal can be anything from blatantly obvious to completely unexpected. To complicate matters, dentists know that any tooth that has been treated with a root canal is structurally weaker than the same tooth with a vital living dental nerve.
If a root canal is needed due to the tooth being physically displaced or due to decay that has indirectly or directly engaged the dental nerve, then the need for a root canal is obvious. If a tooth has been physically hit but not mobilized or decay is deep but does not either visually encroach upon the nerve perimeter or enter the nerve proper, then the tooth may or may not need a root canal in its near future. This tooth will then be at elevated risk of needing a root canal sometime in the future. Sometimes a tooth can have conservative dental restorations or even no restorations yet the dental nerve still dictates the need for root canal therapy. This is often the case for people who clench or brux their teeth with the chronic physical trauma of excess dento-muscular loading causing irreversible inflammation of the dental nerve.
Dentists are limited in both the diagnostic tools available to test a tooth’s dental nerve and the practicality of their use. For example, an x-ray is an after the fact semi-accurate indicator of a dental nerve needing a root canal. This is why an x-ray should only be used as a companion diagnostic tool in the evaluation of dental nerves, unless a dental nerve’s inflammation &/or infection presence is blatantly obvious. Other dental nerve tests involve thermal (cold or hot modalities) and electrical. None of these tests are time efficient to perform on every tooth hence they are omitted from routine (symptom free) exams. Also, theses tests only test for the status of a dental nerve at the time of the test; they are not accurate indicators of future dental nerve viability. It is not uncommon for dental nerves to be tested multiple times over multiple appointments to make a definitive diagnosis of the dental nerves physiologic status.
The physiology of a dental nerve is very instrumental in this on-going saga of unexpected dental nerve symptoms and the resulting need for root canal therapy which results in the need for structural tooth treatment (can range from a filling to a foundation and crown). When an adult tooth comes into the human mouth, assuming it is a healthy normal tooth/dental nerve, then that dental nerve (pulp) is at the most healthy stable homeostasis status it will ever be. When dental nerves are subjected to trauma, they DO NOT HEAL back to 100%. If the trauma induces a reversible inflammation in the dental nerve it will stabilize into a compromised status. Each additional trauma to the dental nerve cumulatively compromises the dental nerve’s ability to remain vital. Dental nerves are traumatized by: clenching, bruxing, increased load due to other teeth missing, decay, cracking, and dental treatment (drilling, adhesives, some materials, treatment techniques, treatment timing) and the hardness of food in one’s diet. Some of the more common causes for a dental nerve to require a root canal are;
- Long term accumulation of traumatic injuries resulting in the dental nerve becoming irreversibly inflamed &/or infected, or
- Acute trauma breaks a tooth and exposes the dental nerve, or,
- Acute trauma mobilizes &/or dislodges a tooth, or
- Decay grows next to or into the dental nerve
Combine the physiology of dental nerves with the limited “snap shot” and “after the fact” diagnostics available to dentists and it is reasonable to see why discomfort &/or pain are often what initiate dental nerve diagnostic protocols for a patient who has been there-to-for dentally healthy and symptom free. Individuals who are not dentally healthy can readily have multiple dental nerve infections and be devoid of pain or swelling until they reach the disease tipping point into a crisis. This most often presents itself as a quickly occurring advanced swelling or pain that is non-responsive to analgesics, prescription or over-the-counter.
When a root canal is required and a root canal procedure is selected to be done (patient wants to save/keep their natural tooth), an access hole has to be drilled through the tooth structure (and any existing dental restoration within the pathway to the nerve) to get to the inside of the tooth where the dental nerve is. A root canal procedure is initiated when the dental nerve is removed from the inside of the tooth body and all of its roots. The resulting space is prepared, disinfected and filled with a compatible material, usually something called gutta percha. The root canal’s access hole must then be restored.
A root canal DOES NOT restore its access hole opening, i.e., it does not restore the structural integrity of the tooth. The type of restoration used to restore the structural part of the tooth depends on several things; was this tooth all natural? Did this tooth already have a restoration? How much volume of tooth did any previous restoration replace, i.e. a small filling, a large filling, an onlay, a foundation and crown? What tooth is this, a back molar, a front incisor? Does it have missing teeth around it? Is this tooth going to be used to help “hold” a prosthetic device like a cemented bridge or a removable partial? Are esthetics & cosmetics a factor? How long does the patient want their tooth’s restoration to last?
The good news is that an experienced knowledgeable clinician can, more times than not, perform a well executed root canal with little to no pain. The reality is that both dentists and patients alike want to minimize the need for root canals. The bad news is that at present time, the dental profession does not have a direct pulpal test that is harmless, consistent, and reliable, while being both diagnostic and predictive. Hence, for the foreseeable future, the saga goes on for all of us.