Root Canal Success Rates and How Long Treated Teeth Last
This page is for anyone weighing up root canal treatment or living with a root-filled tooth. Studies measure success, meaning infection around the root has healed, and survival, meaning the tooth is still in place. Results vary by study, setting and tooth; infection at the root tip beforehand and the restoration afterwards are linked with the outlook.
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Clinically reviewed by Dr Ibraheem Ijaz, dentist · GDC 301711
Medical disclaimer: This page is for general information only. It does not replace an examination or treatment by a dentist.
Dr Ibraheem Ijaz, principal dentist at Deepcar Dental Care, reviewed this page. He is a General Dental Practitioner, GDC 301711, with BDS, BSc (Hons), MSc (Leeds), PG Dip Implant Dentistry and PG Cert Restorative and Aesthetic Dentistry.
What does root canal success mean?
Root canal success usually means the infection around the root tip has healed, while survival generally means the tooth is still in the mouth.
Success is judged on X-rays and examination; survival studies count whether the tooth was kept. A tooth can stay in place without fully healing, so the two should not be combined.
What do published studies report?
Published root canal outcomes depend on what was measured, where and for how long.
| Study and setting | Measured | Found |
|---|---|---|
| Review of 63 studies, 1922 to 2002 (Ng and colleagues, 2007) | Success, first-time treatment, strict criteria, at least 1 year on | 68% to 85% pooled; no improvement in four or five decades; evidence on treatment factors sub-optimal |
| Review of 14 studies, mostly retrospective (Ng and colleagues, 2010) | Survival | 86% at 2 to 3 years, 93% at 4 to 5 years, 87% at 8 to 10 years |
| UK dental hospital, postgraduate students (Ng and colleagues, 2011) | Healing per root; survival per tooth (first-time treatment) | Healing in 83% of roots at 2 to 4 years; 95% of teeth still in place at 4 years |
| US insurance records, 1.46 million teeth (Salehrabi and Rotstein, 2004) | First-time treatment: teeth kept; later re-treatment, surgery or extraction | 97% kept at 8 years; 3% had re-treatment, surgery or extraction |
| 99 US general practices, 71,258 teeth (Thyvalikakath and colleagues, 2022) | First-time treatment: survival without further treatment or tooth loss | 75% at 5 years, 54% at 10 years, 26% at 20 years; the authors note significant limitations |
These results describe the people in each study, not any one practice. Thyvalikakath and colleagues note that insurance-claims studies cover only insured people and typically lack diagnoses.
A 2007 systematic review (Torabinejad and colleagues) found similar long-term survival for single implant crowns and restored root-filled teeth, and higher success rates for implant crowns. But it said differing success criteria made comparing success futile and direct comparisons were extremely rare. Our pages on dental implants and on root canal or extraction cover those decisions.
What most affects how long a root-filled tooth lasts?
The tooth's condition before treatment, the root filling and the restoration over it are among the factors studies link with the outcome.
For healing, a 2008 systematic review of first-time treatment (Ng and colleagues) found four conditions improved success significantly: no lesion at the root tip beforehand, a root filling with no gaps, one ending within 2 mm of the root tip, and a satisfactory restoration. Results varied substantially between studies.
In a 2011 study (Ng and colleagues), a lesion at the root tip before treatment lowered healing, more so the larger it was. Factors linked with tooth loss included pain or a discharging sinus beforehand, diabetes, systemic steroid treatment, deep narrow gum pockets, root perforation and filling pushed beyond the root tip.
How much does the restoration over a root-filled tooth matter?
Evidence suggests the restoration over a root-filled tooth matters as much as the root filling for healing, and studies link a crown with longer survival.
A 2011 meta-analysis of nine studies (Gillen and colleagues) found healing most likely when both were adequate. With only one adequate, poorer outcomes may be expected, with no significant difference between the two.
For survival, Ng and colleagues' 2010 review ranked a crown first of four factors, while calling the evidence weak. Thyvalikakath and colleagues linked a crown with a median survival 5.3 years longer, and Salehrabi and Rotstein found 85% of root-filled teeth later extracted had no full coverage, such as a crown.
Leeds Teaching Hospitals NHS Trust says not having the final restoration done promptly significantly increases the risk of treatment failure or tooth fracture. Brittleness, vertical root fractures and which teeth need a crown or onlay are covered in why a root-filled tooth usually needs a crown.
Questions about this treatment? Book online or call the practice.
Why are root-filled teeth lost?
Root-filled teeth can be lost when infection persists or returns, or for reasons beyond the root canal treatment.
Thyvalikakath and colleagues list decay, gum disease, tooth fractures and failed crowns or bridges among other reasons. Where infection persists or returns, the options are covered on our page on root canal re-treatment.
When is the result of root canal treatment checked?
European Society of Endodontology guidance (2006) recommends judging the result at least one year after root canal treatment, with an examination and an X-ray.
The British Endodontic Society, citing this guidance, calls the outcome uncertain when symptoms are vague or mild and a lesion is unchanged or smaller on X-ray, and advises monitoring until it resolves or for at least four years. A lesion that is new, growing, or still present after four years is among the signs of an unfavourable outcome.
When should you see a dentist about a root-filled tooth?
NHS guidance says the area may feel swollen and sore after root canal treatment, but it should get better in a couple of weeks.
NHS guidance says to see a dentist if you have toothache that lasts more than 2 days, does not go away when you take painkillers, comes with a high temperature, pain when you bite, red gums or a bad taste in your mouth, or comes with a swollen cheek or jaw. Do not go to your GP, as they cannot give dental treatment.
Call your dentist; if they are closed, their answerphone may say what to do. If you do not have a dentist or cannot get an emergency appointment, call 111 or visit 111 online.
Go to A&E if you have toothache and the area around your eye or your neck is swollen, or swelling in your mouth or neck is making it difficult to breathe, swallow or speak. Do not drive to A&E: ask someone to drive you, or call 999 and ask for an ambulance.
Where can you read more about root canal treatment?
Our guide to root canal care explains how treatment clears infection so a tooth can be kept. Restorative dentistry focuses on saving natural teeth rather than replacing them with implants.
Frequently asked questions
How long does a root canal last on average?
There is no single average, because studies count different outcomes. In 99 US general practices (Thyvalikakath and colleagues, 2022), median survival without further treatment or tooth loss was 11.1 years. The authors say this is shorter than most previous studies; their suggested reasons include a broader patient mix, more procedures counted as tooth loss and fewer crowns.
Does the type of tooth affect how long a root canal lasts?
Yes, studies suggest it can. A 2010 systematic review (Ng and colleagues) linked teeth other than molars with better survival, on evidence it called weak. In 99 US general practices (Thyvalikakath and colleagues, 2022), front teeth had a median survival of 12.4 years and premolars 10.3 years, with no significant difference between molars and premolars.
Why do root canal success rates vary so much between studies?
Partly because studies define success differently. A 2007 systematic review of first-time treatment (Ng and colleagues) found studies reporting average success from 31% to 96% when only complete healing counted, and higher figures when a shrinking lesion also counted. Apart from these X-ray criteria, no study characteristic it examined explained the variation.
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