By Linda G. Levin, D.D.S., Ph.D.
As healthcare providers we interface with the public every day. Our conversations range from introductory niceties and diagnostic interrogations to discussions about treatment plans and outcomes. The last topic often evokes the question, “How long will my root canal treatment last?” It’s a valid question and the answer is often rife with contingencies and complexities that vary for each patient and each tooth. Yet, what has stood out to me in these conversations is the patient’s implicit impression that a root canal will last forever. Is that reasonable or even possible to predict reliably? Do patients ask the same questions of their restorative dentists about a composite restoration or crown? Is the reality that all dental work is temporary?
I suspect the answer to the last question is. well, yes. The oral cavity is more hostile than outer space when it comes to manmade materials. I often tell patients that we begin to digest our restorations the minute they are placed. Restorations are occlusally loaded and thermocycled constantly. They are subjected to immediate and unrelenting enzymatic assault and bathed in a microbial-rich salivary soup. When one considers all this, it is amazing that we can restore most teeth back to function for many years. It is also not surprising that imperfect restoration of a root-filled tooth will lead to the demise of even the most precisely executed root canal therapy.
Dentists are not the only healthcare providers who provide prosthetic reconstruction of body parts – our medical colleagues must deal with the same questions of longevity when they place joints, valves, plates or screws. What is their experience? The American Association of Hip and Knee Surgeons states that annual failure rates represent the most accurate way of assessing longevity of joint replacement. They further state that “Most current data suggests that both hip and knee replacements have an annual failure rate between 0.5-1.0%.” They explain that this means that there is a 90-95% chance a prosthetic joint will last 10 years and 80-85% chance it will last 20 years. So, no, prosthetic joints do not last forever.
What about replacement heart valves? The American Heart Association states that a tissue heart replacement valve will last 10 to 20 years or, stated differently, have a reoperation rate of 3.4% per patient per year. A mechanical valve has a reoperation rate of 0.7% per patient per year. So heart valves, like prosthetic joints, do not predictably last forever. In fact, given these statistics, they will most likely fail in a proportion of patients over a 10- to 20-year period. Online patient resources state, “Longevity of an artificial tissue valve depends on many patient variables and medical conditions. This makes it impossible to predict how long a valve or repair device will last in any one patient.” It appears that cardiothoracic surgery and dentistry have more in common than one would think!
In dentistry we have hundreds, if not thousands, of studies designed to look at the long-term success rates of procedures and materials. But what exactly does “long term” mean? Very few endodontic outcome studies observe a defined cohort for more than 10 years. In fact, most dental outcome studies are five years or shorter in length (and many of those are the length of an endodontic residency program). The average size of the cohort is around 100 patients.1 These small study sizes and short observational periods have necessitated the use of power statistics and meta-analysis to fashion meaningful conclusions. So using the best evidence available, we still can only predict endodontic longevity for 5-10 years. Until we have larger and longer-term studies, we cannot know with authority how long our services will last or which factors influence their longevity.
Insurance companies, however, do have access to large amounts of data pertaining to specific dental procedures. A recent study published in the May 2016 issue of the Journal of Endodontics leveraged an insurance company database to evaluate 487,476 endodontic patients over a 10-year period.2 One of the largest endodontic studies ever reported, it presented important data regarding endodontic outcomes and factors that influence success. Notably, the study found that the survival rates of endodontically treated teeth are high even at 10 years after treatment, and that molars treated by endodontists have significantly higher survival rates after 10 years than molars treated by non-endodontists.
Practice-based research networks also offer exciting solutions to the data famine in dental outcomes for both general and specialty care. They represent a consortium of dental practices and dental professionals who conduct practice-based research on various clinical topics, and have the unique potential to answer questions too difficult to address in an academic setting. Funded by the National Institute of Dental and Craniofacial Research and founded in 2005, the National Dental Practice-Based Research Network conducts broad-scale, real-world research on clinical outcomes. The NDPBRN’s recent endodontic pain study resulted in six data-based original articles, with more in progress.
The AAE actively supports the NDPBRN. The Board of Directors and I believe that this network is uniquely positioned to collect the very data our patients are seeking. Upcoming studies designed to assess clinical outcomes from endodontic procedures will examine factors that affect the success of endodontic treatment, as well as the management of anxiety, infection, inflammation and pain. Those of you who attended AAE16 may have noticed the NDPBRN booth where you could register for the PREDICT study investigating post-operative pain. Currently, 117 endodontists are enrolled in the study but they need more. Greater endodontist participation in these studies will help demonstrate that specialists achieve improved treatment outcomes, superior pain management and higher patient satisfaction. Visit the website to enroll.
Let’s work together to find the evidence that shows our patients that saving their natural dentition is their best choice. While the answer to “How long will my root canal last?” may not be “forever” for every case, data from the NDPBRN and other well-designed clinical outcome studies likely will help us to maximize the longevity of our treatments.
- Friedman S, Abitbol S, Lawrence HP. Treatment outcome in endodontics: the Toronto Study. Phase 1: initial treatment. J Endod. 2003;29(12):787-93.
- Burry JC, Stover S, Eichmiller F, Bhagavatula P. Outcomes of primary endodontic therapy provided by endodontic specialists compared with other providers. J Endod. 2016;42(5):702-5.