Single-Visit vs. Multiple-Visit Endodontic Treatment: A Review

There are differing opinions regarding single-visit vs. multiple-visit endodontics.  Some clinicians feel strongly that teeth with apical periodontitis (necrotic or retreatment) need the extra step of CaOH therapy to be successful while others are comfortable with these cases being done in a single visit.  What does the research say regarding this?  Here's a summary of the more recent research:

Please note that the systematic reviews, in an effort to summarize the existing research and find the best evidence, exclude review papers, case studies, review studies and studies that are determined to be "low evidence" and focus on randomized clinical trials or quasi-randomized clinical trials.  However, like most of our dental research, there is a serious lack of studies that can be considered "high-level" evidence, large enough sample size, good research design and proper identification of study bias.  This is a problem found throughout our scientific research and requires the reader to evaluate the quality of research on a study by study basis.

Single versus Multiple Visits for Endodontic Treatment of Permanent Teeth (A Cochrane Review) by Manfredi et. al. 2016, included in their review, 25 randomized controlled trials, of which only 3 studies were found to be a low risk of bias, 8 unclear bias levels and 14 high bias levels.  They found no evidence of a difference between single visit or multiple visit treatment in terms of radiological failure, immediate post operative pain, swelling or flare-up incidence, sinus tract formation or complications.  There was moderate evidence that patients undergoing single step treatment were more likely to use painkillers over those undergoing multiple visit treatment.

A Systematic Review of Nonsurgical Single-Visit Versus Multiple-Visit Endodontic Treatment by Wong et. al 2014 which reviewed a total of 47 papers of clinical trials on the subject.  Meta-analysis showed that post-operative complications of both groups were similar.  Neither group could guarantee the absence of post-operative pain.  Neither single-visit or multiple-visit treatment had superior results in terms of healing or success rates.

Single-Visit or Multiple-Visit Root Canal Treatment: Systematic Review, Meta-Analysis and Trial Sequential Analysis by Schwendicke et. al. 2017 included 29 trials (4341 patients), of which all but 6 showed high risk of bias. Based on 10 trials, risks of complications was not significant. Based on 20 studies, risk of pain was not significant. Based on 8 studies, risk of flare-up was higher in single-visit treatment.  Conclusion was insignificant evidence to rule out whether important differences between these strategies exist.

Outcome of Single- vs. Multiple-Visit Endodontic Therapy of Non-Vital Teeth: A Meta-Analysis by Almeida et. al. 2017 is a review of 17 randomized clinical trials of non-vital teeth.  They found no difference between single or multiple visit treatment in regard to peri-apical repair or microbiological control.  They did find that single-visit treatment results in 21% less post-operative pain.

Single-Visit More Effective Than Multiple-Visit Root Canal Treatment? by Hargreaves 2006 is a review that includes 3 randomized controlled trials including 146 cases. In this review, included NSRCT of teeth with necrosis or signs of periapical bone loss - excluding pretreatment and surgical tx. It was concluded that single-visit root canal treatment was slightly more effective than multiple-visit treatment with a 6.3% higher healing rate. However this difference was not statistically significant (P = 0.3809).

Single Versus Multi-visit Endodontic Treatment of Teeth with Apical Periodontitis: An In Vivo Study with 1-Year Evaluation by Gill et. al 2016, found no significant differences in healing between teeth treated in single visit, multi-visit without dressing and multi-visit with CaOH dressing.

Treatment Outcomes of Single-Visit Versus Multiple-Visit Non-Surgical Endodontic Therapy: A Randomized Clinical Trial by Wong et. al. 2015, was a university study performed by general dentists, on 220 patients followed for at least 18 months. They reported no significant difference in success rate or prevalence of post-operative pain between the single visit or multiple visit treatments.

In my opinion, the evidence does not support that multi-step initial endodontic treatment, even of necrotic teeth, has any significant improvement in outcomes over single step treatment.  In my experience, patients usually prefer to have their endodontic treatment in single-step treatment as well.

BIAS ALERT:  In an effort to identify my own biases, I would share that I perform the majority of my endodontic procedures in a single-step.  I do use CaOH occasionally on retreatment cases that are not healing as expected or when I run out of time to complete treatment in a single step.

GentleWave by Sonendo: A Third Look

We recently had an in-office demo of the GentleWave procedure by Sonendo, Inc. (Laguna Hills, CA).  We had a great team from Sonendo who came to our office and gave a us a presentation and demonstration, including the opportunity to perform the procedure on an extracted tooth.  We spent almost 3 hours together learning about GentleWave.

The presentation was very informative and clearly explained the unique approach of the GentleWave system.  This included a history of its development with some amazing visual imaging of the technology and how the multi-sonic energy and fluid dynamics are used to clean the canal system.  We also had Dr. Mehrzad Khakpour, a GentleWave co-founder, on a conference call to answer any questions.

There is no doubt that the GentleWave system by Sonendo is a novel and unique approach to the endodontic challenge of cleaning root canal systems.  There are a several things I find very interesting about the GentleWave approach which I really like.

1. The multi-sonic energy and fluid dynamic approach to enhance irrigation and cleaning is very interesting.
2. The minimalization of canal shaping with files continues to move us in a conservative direction to preserve maximum tooth structure.
3. The concept of a negative pressure and evacuation of the irrigants and debris through the treatment instrument is a great idea.
4. The de-gassed irrigants ability to penetrate the complexities of the canal system.
5. The removal of smear layer using multi-sonic and fluid dynamics.
6. For those who do 2-step treatment, this may be a way for them to feel more comfortable with single step treatment - which patients prefer.
7. Sonendo insists that they are focused on continuing the clinical research.
8. Sonendo does have a volume discount for treatment instruments, which gives the endodontist a slight economic advantage over a general practicioner.
9. The technology is really cool. Who doesn't like new technology?

 Here are some of the questions or concerns that I have about the GentleWave procedure:

1. We have current ways to create sonic or ultrasonic activation in the canal system.  These work very well and are much faster and less expensive the GentleWave.
2. With the GentleWave procedure, you still have to locate all the canals, including calcified canals, get patency and open them up to a minimal size.  This is the most difficult and time consuming part of the endodontic procedure.  GentleWave does not solve those problems.  No time saved there.
3. Cost of the treatment instrument, materials to create the platform, additional volume of irrigants and sealers double or triple the material overhead costs of the treatment.
4. Using the GentleWave procedure will add time to the procedure. It has been estimated by one clinician currently using it that it takes 30% more time per case (20 min for this practitioner).  This would decrease the number of patients that could be treated each day.
5. The claims being made regarding improved success rates and decreased post-op sensitivity are anecdotal.
6. Hidden costs of ownership make this technology much more expensive than it appears.  A business model that requires up to 73% of the cost of the initial investment in disposable, single use treatment instruments per year (in order to get the discounted rate) ends up being a much bigger investment.
7. Will insurance companies really allow contracted clinicians to charge additional "non-covered" fees to the root canal procedure?

Being among the earliest adopters of microscopes and CBCT in Arizona, we have been through the process of evaluating new technologies and their impact on the clinical practice of endodontics.  When it comes to incorporating a new technology into practice, it should be able to:

1. Make you better - improve outcomes
2. Make you faster - more efficient
3. Make you more profitable

The GentleWave procedure will not make you faster or more profitable and there is not enough evidence to determine if it would make you better by improving outcomes significantly for patients.

This technology is fascinating. However, for such a large expense, it would be foolish to incorporate any technology into a practice that can so profoundly affect the overhead and productivity of the practice without doing an adequate cost benefit analysis, measuring the opportunity cost and evaluating the return on investment.