· 7 min
When someone hears they need a root canal, the first question is usually whether it will hurt. The second, almost always, is whether it would be better to just pull the tooth. I'm Dr. Valentina Gormaz; I hold a Master's in Endodontics from the University of Valencia and I perform root canals at AS Odontología Digital in Vitacura. In this article I explain what the treatment is, when it's indicated, what it feels like and what makes a treated tooth last for many years.
A root canal, also called endodontic treatment or endodontics, is treatment of the inside of the tooth. Every tooth has a chamber at its center and one or more canals running down the root. That's where the pulp lives, a tissue with nerves and blood vessels that forms the dentin during development and gives it sensation in adulthood. When the pulp becomes irreversibly inflamed or infected, a root canal removes it, cleans and disinfects the canals, and seals them so bacteria can't get back in. The tooth stays in place and in function, with its natural root anchored in the bone.
People often describe it as "killing the nerve", a phrase that sounds scarier than it is: what's removed is diseased tissue that can no longer recover, in order to save the rest of the tooth.
The most common cause is a deep cavity that reaches the pulp. It can also be a fracture that exposes the nerve, an old knock to the tooth, or a large filling that leaked over the years. What the diagnosis looks for is the state of the pulp.
Irreversible pulpitis: the pulp is inflamed and won't recover. It usually causes spontaneous, throbbing pain that wakes you at night or keeps going after the cold is gone. If you haven't yet read what to do while you wait for your appointment, tooth pain: what to do and when it's urgent walks through it step by step.
Pulp necrosis: the pulp has died. Often the pain disappears at that point, which is why some people believe the problem solved itself. In reality the bacteria are still inside the tooth and can form a lesion in the bone, sometimes with swelling or a fistula, a small pimple on the gum where the infection drains. A tooth that darkened after a knock can also be in this situation.
The diagnosis is made with a clinical exam, tooth sensitivity tests and an X-ray. When the anatomy is complex or the X-ray isn't enough, a cone-beam CT (CBCT) scan may be added.
During treatment, with local anesthesia, you can expect pressure and vibration, but not pain. When a tooth arrives very inflamed it's often harder to numb, and the anesthesia is topped up during the visit; that's common.
The data are reassuring. A systematic review of 72 studies found pain in 81% of patients before treatment, 40% at 24 hours and 11% at one week, with intensity dropping sharply from the first day (Pak and White, 2011). In other words, most people arrive in pain and leave better than they came. Some tenderness when chewing for a few days is normal. If the pain increases instead of easing, or swelling appears, let your dentist know.
The treatment follows a fairly standard sequence. First the area is numbed and the tooth is isolated so we can work in a clean, dry field. Then a small opening is made through the biting surface, or from behind on front teeth, to reach the pulp chamber. The canals are located, the diseased tissue is removed, and the canals are cleaned and disinfected along their full length. Finally they're filled and sealed, and the tooth gets a temporary or definitive restoration depending on the case.
Canals are very narrow and their shape varies a lot from tooth to tooth, especially in molars. That's why I work with magnifying loupes: seeing better makes it possible to find canals that go unnoticed with the naked eye, and a canal left untreated is one of the reasons a root canal can fail.
It depends on the case: one visit or two. When the tooth is inflamed but without an established infection, it's often finished in a single appointment. When there's infection, a lesion in the bone or difficult anatomy, sometimes medication is left inside the tooth and the treatment is finished at a second visit. The evidence supports both options. A Cochrane review of 25 trials found no evidence of a difference between one and several visits in radiological failure or complications, although people treated in a single visit used painkillers more often in the following days (Manfredi et al., 2016). The decision is made based on the state of the tooth at the start.
A tooth with a root canal loses part of its structure, both from the decay or fracture that led to treatment and from the opening that was made. Without a restoration that protects it, it's more likely to fracture or to let bacteria back in. In a retrospective study of 203 teeth, root-canal-treated teeth that didn't receive a crown were lost at a rate six times higher than those that did (Aquilino and Caplan, 2002).
That's why, in molars and premolars, the usual approach is to protect the tooth with a dental crown or an onlay covering the cusps, depending on how much healthy tooth remains. In front teeth with little loss of structure, a direct filling is sometimes enough. What you shouldn't do is leave the tooth with the temporary filling for months.
A well-done, well-restored root canal can keep the tooth in place for many years. A systematic review of 63 studies estimated success rates between 68% and 85% using a strict criterion: complete disappearance of the bone lesion on the X-ray (Ng et al., 2007). Factors associated with a better outcome include the tooth's condition before treatment, the quality of the canal seal and a good restoration on top.
When an old root canal fails, with persistent pain, a fistula or a lesion that won't heal, it can often be redone with a retreatment before considering extraction.
If the tooth can be restored, keeping it is usually the first option. Your natural root preserves the bone, the gum and the feel of chewing, and a well-treated natural tooth is hard to beat. There are cases where a root canal isn't the best idea: fractures that extend into the root, teeth with very little structure left, or advanced bone loss. Then extraction and replacement are weighed, as we discuss in implants or natural teeth: when to keep and when to replace.
If you have pain, a darkened tooth or a fistula on the gum, what you need is an evaluation with an X-ray. At AS Odontología Digital you can book through our endodontics page, and if there's swelling or severe pain, our emergency dentist page lets us coordinate care over WhatsApp.
If this article left you with questions, explore the related services or book an evaluation at AS Odontología Digital in Vitacura.
Book an evaluationIt's treatment of the inside of the tooth when the pulp, the tissue with nerves and vessels at its center, becomes irreversibly inflamed or infected. That tissue is removed, the root canals are cleaned and disinfected, and then sealed. It's also called endodontic treatment, and it lets you keep the tooth instead of extracting it.
With local anesthesia, you feel pressure and vibration during treatment, but not pain. Afterwards some tenderness when chewing for a few days is normal. A review of 72 studies showed pain drops sharply from the first day and persists at one week in only a minority of patients. If the pain increases or swelling appears, contact your dentist.
One or two, depending on the case. When there's no established infection it's often finished in one appointment. If there's infection, a lesion in the bone or complex anatomy, sometimes medication is left inside the tooth and the treatment is finished at a second visit.
In molars and premolars, it's almost always worth protecting the tooth with a crown or an onlay covering the cusps, because it has lost structure. A retrospective study found that root-canal-treated teeth without a crown were lost at a rate six times higher. In front teeth with little loss of structure, a direct filling is sometimes enough.
Done and restored well, it can last many years. Factors that influence it include the tooth's condition before treatment, the quality of the canal seal and the restoration placed on top. If an old root canal fails, it can often be redone with a retreatment.
If the tooth can be restored, keeping it is usually the first option, because the natural root preserves the bone and gum. Extraction and an implant are considered when a fracture reaches the root, there's very little tooth structure left or there's advanced bone loss. The decision is made with an exam and an X-ray.
