One Visit or Two? Why I Don't Finish Every Root Canal in One Appointment
I finish most root canals in one visit. That's especially true for vital cases. But for a hot tooth or a chronic apical abscess with a sinus tract, I often choose two visits. The reason isn't that two visits heal better. It's that the patient has a better experience, and in private practice that experience is your reputation.
What the evidence says
The research is fairly settled: healing is about the same either way. A Cochrane review published in the Journal of Endodontics found no difference in radiographic success. A randomized trial in teeth with apical periodontitis reported 96.6% healing with one visit and 89.0% with two at 2 years. That difference was not statistically significant.
The case for two visits comes from microbiology. Vera et al. found fewer bacteria left in isthmuses and ramifications after a calcium hydroxide dressing. Xavier et al. found two visits with calcium hydroxide reduced endotoxins more. So neither approach is wrong. The choice comes down to the case and the patient.
When I finish in one visit
Vital pulp cases, where the canal space isn't yet infected, are my one-visit cases. If I can get good anesthesia and complete the cleaning protocol, there's little reason to bring the patient back.
When I choose two visits
The hot tooth. These patients arrive in severe pain, and profound anesthesia can be hard to get. At the first visit, my goal is to get them out of pain: remove the inflamed pulp, place calcium hydroxide and close. When they return, they're calm, they numb easily and the finishing appointment is painless. That's the appointment they remember and tell their friends about.
Chronic apical abscess with a sinus tract. I place calcium hydroxide between visits. At the second appointment, I can usually show the patient that the fistula has closed. They see healing with their own eyes before I obturate, and the finish is comfortable.
The practice-building case
In the U.S., the procedure is typically billed when the root canal is completed, so finishing every case in one visit is tempting. But reputation compounds. Being known as the office that does painless root canals brings referrals and returning patients. That's worth more than one extra appointment on the schedule. The Cochrane review above also found single-visit patients were more likely to need painkillers afterward, which fits what I see in hot and infected cases.
A note for residents
Training clinics work differently. In dental school and residency, many patients don't return for a second visit once they're out of pain. So residents are often forced to finish in one visit, whatever the diagnosis. In private practice, patients usually do come back, and you have more freedom to choose.
Learn to do both well. Flexibility is what lets you succeed in whichever setting you end up in.
Google Reviews
One comment I wanted to mention is the google reviews. They are difficult to manage but it is crucial to keep up with your reputation online. Most google reviews address these things:
If you and the office staff are friendly
If it was painless
If the office was clean
If it was fast
Notice most office reviews (unless patients themselves are dentists) are not about thanking them for finishing cases to radiographic apex (which is a trend in some areas), or that you made sealer puffs. The main point I wanted to make is that you need to focus on doing painless root canals which will be discussed in later series.
What actually heals the tooth: cleaning and sealing
One visit or two, the number of appointments doesn't heal the tooth. Cleaning and sealing do. Three things matter most:
Apical preparation size. The apical foramen is commonly about 0.25 mm across, roughly a size 25 file, and often larger. In one study of mandibular first molars, foramen diameters ranged from about 0.24 to 0.38 mm. Stopping at a 25 may leave the apical walls untouched. I finish most canals to at least a size 30, and larger in retreatments. A randomized trial by Saini et al. found that enlarging 3 or more sizes beyond the first binding file healed better than enlarging only 2.
Irrigation volume and exchange. Siqueira et al. found that 1%, 2.5% and 5.25% NaOCl reduced bacteria about equally. They concluded that frequent exchange and large volumes of irrigant make up for concentration. My protocol is 10 to 15 minutes of total irrigation time, with ultrasonic activation. A literature review by van der Sluis et al. found that passive ultrasonic irrigation removes more tissue, bacteria and debris than syringe irrigation alone. Some clinicians say they irrigate for up to 2 hours, but that isn't practical in a private practice schedule. A second visit gives you another full round of irrigation, plus a medicament working in between.
Obturation that entombs what's left. No cleaning protocol removes every bacterium. Sjögren et al. reported 94% healing when canals cultured negative at obturation, versus 68% when bacteria remained. So clean first, then seal. A dense, well-adapted fill with sealer entombs the bacteria left behind, cutting off their space and nutrients. A tight coronal seal then keeps new bacteria out. Ray and Trope found 91.4% of teeth with both a good root filling and a good restoration had no periapical inflammation, versus 18.1% when both were poor.
Bottom line
One visit for most vital cases. Two visits when it makes the patient's experience better, especially the hot tooth and the draining abscess. And in every case, size the apex properly, irrigate generously and seal it completely. That's where success comes from.
Next in the series, Part 2: calcium hydroxide. I'll cover when I use it, how long I leave it in, and why it makes the second visit so comfortable.
References
Reference | Summary |
|---|---|
Similar healing; more analgesic use after single visit | |
96.6% vs 89.0% healed at 2 years, not significant | |
Similar healing in infected canals | |
Calcium hydroxide reduces residual bacteria in isthmuses | |
Two visits with calcium hydroxide reduce endotoxins more | |
Enlarging 3+ sizes beyond first binding file improves healing | |
Irrigant volume and exchange offset concentration | |
Ultrasonic activation removes more tissue, bacteria and debris than syringe irrigation | |
94% healing with negative culture at obturation vs 68% with positive | |
Good root filling + good restoration: 91.4% without periapical inflammation; both poor: 18.1% | |
Foramen diameters about 0.24–0.38 mm | |
no significant healing difference |
