Whether it comes from patients or general dentists, one thing that I get asked pretty often is this: “Why do root canals take 2 visits sometimes? And how is it decided whether a root canal will take one appointment or multiple?”

This is actually a really, really important question. 

Naturally my first response is: Well, it depends on the case. 

But after years of experience, I have learned that there are some factors that guide my decision as an endodontist whether to treat a tooth with a single visit or more than one. 

I’ll walk you through a few scenarios.  

The Emergency Patient

When I get an emergency patient who needs same day treatment that I have to work into my schedule, that patient won’t be getting treatment done in one visit. The reason for this? It’s simply because of time. 

I don’t want to have to reschedule tons of patients who may have had their appointments for months—so I typically don’t treat these emergency cases to completion.

I’ll do a pulpectomy or a full pulpal debridement in order to make sure the patient has  enough pain control to move on with their life and schedule a follow-up to complete their root canal in the meantime. 


One big reason why root canals take 2 treatments is often because of retreatments. The majority of patients that come to me for a retreatment get done in two separate visits, since they always tend to have a more serious infection than a patient that’s just getting an initial root canal. 

Occasionally I’m able to treat these patients in a single visit if it’s an anterior tooth and I want to get the patient back to their general dentist quickly to have the tooth restored with a post and a core. 

Another scenario that might require just one visit is if there’s retreatment just because of some coronal leakage, and there’s no real periapical radiolucency. In a case like that I just refresh the gutta percha and—voilà!—the case is done. 

So, while there are some exceptions to the “retreatments require multiple visits” rule, typically, these are patients that will need to visit the clinic again.  

The Symptomatic Patient

Here’s another twofer: if a tooth is too symptomatic. That is, if the patient comes in with a lot of pain, it’s often just not a good idea to do a root canal in one visit. 

Okay, so symptomatic patients often need 2 root canal visits. Why? 

Because I always want my patients to go back to their general dentist pain free. In order to control their pain, if they’re feeling really bad before treatment, I will usually medicate the tooth with calcium hydroxide and make sure they can function normally by the time they go back to get their final restoration. This takes extra time—which usually means two visits.


If a patient is swollen or they are draining in any way, then I prefer two visits to treat them. I want their infection to be completely resolved before I start to obturate that canal.  

It’s always a good idea to make sure your canals are bone dry before you obturate. And that’s a good reason to pencil in two appointments. 

Pain During Treatment

When a patient feels me working during a root canal, even with adequate anesthesia, I will extend the treatment to two visits. This is one of those scenarios that can be really touch-and-go. I often have every intention of filling the tooth in one visit, but if a patient is really uncomfortable, then I prefer to take a little more time. 

This is pretty unusual, but I believe good things take time. I think one of the best things about root canal therapy is that you can just close it up and come back to it another day. This means you never have to (and never should!) rush a treatment. Always take your time and make sure your patient is pain free before they get their crown. 

The Large Periapical Radiolucency

Sometimes when a periapical radiolucency is WAY too big, I want to extend my work over the course of two visits because occasionally these cases need some surgical intervention in between—they just won’t heal with root canal therapy alone. 

When I anticipate a post-operative flare up because of the size of the lesion, two visits is much better than one. 

Special Cases

Here’s a catch-all: when there’s something special going on a tooth—maybe some resorption, or special anatomy (like C-shaped anatomy)—then I will schedule multiple visits. 

If you see anything that throws you through for a loop, or is just not super common, I suggest two visits to make sure you have a working plan. 

Difficult Teeth

The last common reason why a root canal might take 2 visits is because you’re working on a hard tooth. 

I’ll be completely honest: Not every root canal is a slam dunk for me. Some cases that I think are going to be so straightforward based on the radiograph are actually really tough when I get inside the tooth.

What can you do then? Spread the treatment out over two visits and make sure you do the best root canal you possibly can!

Why Do Some Root Canals Take 2 Visits? Talking Through Scheduling with Your Patients

When I talk to a patient during their evaluation and am orienting them about their procedure, I let them know that they should expect two visits for their root canal, but I also let them know that I’ll try to get it done in just one. This language makes sure that their expectations are managed and appropriate. I never promise anybody one visit, although I do make it happen about 85% of the time.

I take this approach because root canals are SO technique sensitive and I want to take my time, do it right, and give every patient the highest quality of care. 

My reasoning for never promising a single visit and spreading out the treatment across two visits when necessary is that I never want to look at that tooth ever again! I want to make sure that when that tooth is treated with a root canal by me, they don’t have to come through my door ever again for the same problem. 

I hope this information is helpful for you going forward. 

What’s your approach to discussing treatment and planning with your patients? Let me know in the comments!

– Sonia