After a root canal treatment, the survival of the tooth depends heavily on the way it is restored. In some cohorts, a tooth left without a crown was lost 6 times faster, so the quality of the treatment and the final restoration have to be assessed together.
If a root canal treatment has been proposed, has failed or remains painful, Noria Health Hub can arrange a full check-up or a second medical opinion in Brussels, with a report within 24 h, coordinate your care where needed across more than 40 medical pathways in 48 h, then, if your medical condition allows, arrange surgery within 7 days.
Root canal treatment, telling biological success from tooth survival
The distinction has to be set out before any figure. Success means healing, that is, the disappearance of the image at the root tip and the absence of clinical signs. Survival simply means that the tooth is still in the mouth. A tooth can survive a long time without being healed. This is the number 1 source of discrepancy between published figures.
| What is measured | The result |
|---|---|
| Weighted success, strict criterion, meta-analysis of 40 studies | 74.7% |
| Weighted success, loose criterion | 85.2% |
| The same, across 42 studies published 2003 to 2020 | 82.0% strict, 92.6% loose |
| Tooth survival at 8 years, 1,462,936 teeth from a US insurance database | 97% |
| Survival at 20 years, 598 teeth followed 5 to 37 years | 81%, and 76% at 30 years |
The insurance line covers 1.46 million teeth, which makes it the largest cohort in existence. But it measures retention, not healing. The 2 pieces of information are useful, provided they are not mixed up.
One awkward datum completes the picture and it is rarely quoted. Across 300,861 teeth analysed in 33 cross-sectional studies, 36% of endodontically treated teeth carry an image at the root tip, against 2% of untreated teeth. It is not a failure rate, because an image can be in the process of healing. It is the reality on the ground, and it is harsher than the figures from controlled trials.
The way the tooth is restored strongly influences its survival
This is the most solid result in the whole file and the most directly useful in practice for a patient.
| What is measured | The result |
|---|---|
| Treated teeth without a crown, rate of loss | 6.0 times faster |
| Survival with a crown | 94% at 5 years, 89% at 10 years |
| Survival without a crown | 77% at 5 years, 62% at 10 years |
| Share of extracted teeth with no full coverage, across 1.46 million teeth | 85% |
| Crown placed more than 4 months after treatment | Extraction risk multiplied by 3.38 |
The last line is the one nobody explains. It is not only the crown that matters, it is the delay before placing it. Waiting more than 4 months triples the risk.
A series of 119 consecutive extractions of treated teeth gives the real causes of loss. Periodontal disease 40.3%, endodontic failure 19.3%, unrestorable fracture 15.1%, vertical root fracture 13.4%, unrestorable caries 5.2%. In other words, only 1 extraction in 5 is a root canal failure in the strict sense. The rest is periodontal, restorative or fracture-related. In the same series, only 5.9% of the extracted teeth carried a crown.
The factors associated with a better outcome
| What is measured | The result |
|---|---|
| Rubber dam, national database of 517,234 teeth | Extraction risk reduced, hazard ratio of 0.81 |
| Operating microscope, mesiobuccal root of maxillary molars | 3 times more lesions at retreatment if the initial treatment was done without one |
| Apical microsurgery against traditional surgery | 94% against 59% success |
| Absence of a pre-existing lesion against presence | Odds ratio of 1.95 favouring absence |
| Treatment in 1 visit against several | No difference in success, odds ratio 1.16 |
The last line settles a very widespread debate. The number of visits does not change the result. The rubber dam, the microscope and the quality of the final restoration do.
Persistent pain, an outcome distinct from radiographic success
Anaesthesia fails more often than patients, and many clinicians, believe. Across 5,094 patients and 46 randomised trials, the success rate of pulpal anaesthesia in irreversible pulpitis is 52%, all strategies taken together.
The detail is starker still. With an inferior alveolar block using lidocaine alone, success is 28% on first molars, 25% on second molars and 39% on premolars. With a supplementary articaine infiltration, that rises to 42, 48 and 73%. What works best in the network meta-analysis is intraosseous injection, with the best confidence level in the network.
After treatment, acute pain affects about 8.4% of cases, and 13.6% in the retreatment of a tooth with a lesion. One figure deserves to be known by those still in pain long afterwards. Persistent pain beyond 6 months affects 5.3% of teeth, and above all, 56% of that persistent pain is not of dental origin. Retreating or extracting will not relieve it.
Treatment failure, retreatment, surgery or extraction?
| What is compared | The result |
|---|---|
| Orthograde retreatment, 17 studies | 77% success |
| At 2 to 4 years, apical surgery against retreatment | 77.8% against 70.9%, advantage to surgery |
| At 4 to 6 years, the same | 83% against 71.8%, advantage to retreatment |
| Microsurgery against retreatment, beyond 4 years | 82.5% against 81.7%, convergence |
| Teeth still in the mouth 5 years after specialist retreatment, 4,744 teeth | 89% |
The reversal over time is the major result of this table. Surgery heals faster, retreatment holds better over the long run. That is what justifies the usual order, retreat first.
On the comparison with extraction followed by an implant, we have to be categorical about what is known. No randomised trial has ever directly compared root canal treatment and a single implant on the same tooth. A matched study of 196 against 196 cases finds identical failure rates, 6.1% in both groups, but 5 times more reinterventions on the implant side, 17.9% against 3.6%. A 2025 systematic review of 12 studies concludes that no meta-analysis is possible and that complications and reinterventions are more frequent on the implant side.
Other, more recent work gives the advantage to the implant on raw survival. We cite the 2 sets of findings, because the populations are not comparable. Implant cohorts select favourable sites, endodontic cohorts include teeth that are already heavily broken down. Any commercial claim in either direction goes beyond the evidence.
Antibiotics, still prescribed far too often
| The clinical situation | Share of clinicians prescribing an antibiotic where it is not indicated |
|---|---|
| Symptomatic apical periodontitis without swelling | 25.8% |
| Asymptomatic apical periodontitis or chronic abscess | 31.5% |
| Acute apical abscess without marked symptoms | 47.7% |
| Acute abscess with moderate to severe symptoms | 88.8% |
These figures cover 34 to 38 studies and up to 15,629 clinicians. The 2019 American guideline is a strong recommendation not to prescribe an antibiotic in irreversible pulpitis in an immunocompetent adult, nor as an adjunct to immediate dental treatment.
The Cochrane review on the subject includes a single randomised trial of 40 participants, in which penicillin changes neither pain nor ibuprofen consumption compared with placebo. The evidence is insufficient, and it does not point towards prescribing.
Cone beam CT can reveal lesions invisible on a standard radiograph
Three-dimensional imaging sees far more than a conventional radiograph. Across 273 roots examined by the 2 methods in the same patients, an apical lesion is seen on 20% of roots on radiography against 48% on cone beam.
The consequence is counter-intuitive and it deserves saying. In a retreatment trial, success at 1 year was 93% measured on conventional radiography and 77% measured on cone beam, on the same teeth. In other words, all the historical success rates of 90 to 95% rest on two-dimensional imaging, and they fall mechanically as soon as you look more closely.
The joint guidance of the American endodontic and maxillofacial radiology societies reserves small-field cone beam for specific situations, contradictory signs, complex anatomy, suspected vertical root fracture, treatment failure, surgical planning. It is never a routine examination. And there is no randomised trial demonstrating that ordering a cone beam improves tooth survival.
Devitalised teeth and general health, what the data show
For a century, the idea has circulated that a devitalised tooth is a source of chronic infection responsible for general disease. That theory, known as focal infection, was dominant in the 1920s and was abandoned because it rested only on anecdotal observation. It has returned through social media and through a documentary withdrawn from the platforms in 2019 at the request of several professional bodies.
Here is what recent data actually say, and 2 things have to be distinguished. Untreated infection at the root tip is associated with excess cardiovascular risk in several studies. The treated tooth is not, once confounders are accounted for. The best prospective follow-up available, about 8 years across 805 matched subjects, concludes that endodontically treated teeth have limited value as a risk indicator after adjustment, and that it is tooth loss that is a strong indicator.
On cancer, we have information to give and it is an absence. We found no epidemiological study establishing a link between root canal treatment and cancer, in either direction. The claim that a very large majority of cancer patients have had a root canal treatment has no verifiable primary source. The absence of data is itself the information.
Two received ideas corrected by the studies
The first, that a devitalised tooth is dried out and brittle. Dentine water content was measured on pairs of contralateral teeth, 12.35% in vital teeth against 12.10% in treated teeth. No significant difference.
The second, that it is devitalisation that weakens the tooth. Measurement says otherwise. All the endodontic steps together reduce cusp stiffness by only 5%. A simple occlusal cavity reduces it by 20%, and a cavity taking the 2 marginal ridges by 63%. It is not the treatment that weakens the tooth, it is the loss of structure that made the treatment necessary.
International patients, checking who may legally carry out the treatment
One practical point deserves to be known by anyone treated abroad. Across 21 European countries studied, only about 24% officially recognise endodontics as a dental specialty. The European directive on the recognition of qualifications explicitly recognises only 2 dental specialties, orthodontics and oral surgery. The word endodontist therefore does not carry the same legal content from one country to another.
We found no published data on waiting times to see an endodontist in Europe, the United Kingdom or Canada. We flag that rather than transpose a figure from another specialty.
What the studies do not allow anyone to claim
We will not write that root canal treatment succeeds in 95% of cases, because that figure measures retention rather than healing, and because it falls 16 points as soon as you look in three dimensions. We will not claim that an implant is better, or the reverse, because no randomised trial has ever made that comparison. You will not read here that a devitalised tooth makes you ill, because the best prospective data available says the opposite after adjustment.
What we will say is that the heaviest factor, measured at 6 times over, is not inside the canal. It is in what is placed on top, and in how long it takes to place it.
In practice, if this concerns you
You set out your problem, your symptoms or your question. Reports, test results and images already available can be studied before you arrive, so that the pathway is prepared. The aim is not to run every examination as a matter of course, but to select those that can genuinely help confirm a hypothesis, rule out a risk or guide a decision. The findings are then summarised and the next steps organised. Follow-up is coordinated from there.
Need medical advice quickly? For a worry that does not call for the emergency services, you can ask to speak to a doctor at any time through Noria Health Hub. This on-demand medical consultation is billed separately from the assessment pathway.
Further reading
The companion articles.
Caries” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/caries-the-most-widespread-and-the-least-well-decided/”>Caries, the most widespread disease
Replacing” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/replacing-a-tooth-what-lasts-and-what-gets-repaired/”>Replacing a tooth, lifespan, complications and follow-up
Sources
Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K, Outcome of primary root canal treatment, systematic review of the literature, part 1, International Endodontic Journal, 2007. https://doi.org/10.1111/j.1365-2591.2007.01322.x
Ng YL, Mann V, Gulabivala K, Outcome of secondary root canal treatment, systematic review, International Endodontic Journal, 2008. https://doi.org/10.1111/j.1365-2591.2008.01484.x
Ng YL, Mann V, Gulabivala K, Tooth survival following non-surgical root canal treatment, a systematic review, International Endodontic Journal, 2010. https://doi.org/10.1111/j.1365-2591.2009.01671.x
Ng YL, Mann V, Gulabivala K, A prospective study of the factors affecting outcomes of non-surgical root canal treatment, parts 1 and 2, International Endodontic Journal, 2011. https://doi.org/10.1111/j.1365-2591.2011.01872.x
Burns LE, Kim J, Wu Y, Alzwaideh R, McGowan R, Sigurdsson A, Outcomes of primary root canal therapy, an updated systematic review of longitudinal clinical studies, International Endodontic Journal, 2022. https://doi.org/10.1111/iej.13736
Salehrabi R, Rotstein I, Endodontic treatment outcomes in a large patient population in the USA, an epidemiological study, Journal of Endodontics, 2004. https://doi.org/10.1097/01.don.0000145031.04236.ca
Salehrabi R, Rotstein I, Epidemiologic evaluation of the outcomes of orthograde endodontic retreatment, Journal of Endodontics, 2010. https://doi.org/10.1016/j.joen.2010.02.009
Pak JG, Fayazi S, White SN, Prevalence of periapical radiolucency and root canal treatment, a systematic review of cross-sectional studies, Journal of Endodontics, 2012. https://doi.org/10.1016/j.joen.2012.05.023
Aquilino SA, Caplan DJ, Relationship between crown placement and the survival of endodontically treated teeth, Journal of Prosthetic Dentistry, 2002. https://doi.org/10.1067/mpr.2002.122014
Pratt I, Aminoshariae A, Montagnese TA, Williams KA, Khalighinejad N, Mickel A, Eight-year retrospective study of the critical time lapse between root canal completion and crown placement, Journal of Endodontics, 2016. https://doi.org/10.1016/j.joen.2016.08.006
Touré B, Faye B, Kane AW, Lo CM, Niang B, Boucher Y, Analysis of reasons for extraction of endodontically treated teeth, Journal of Endodontics, 2011. https://doi.org/10.1016/j.joen.2011.07.002
Lin PY, Huang SH, Chang HJ, Chi LY, The effect of rubber dam usage on the survival rate of teeth receiving initial root canal treatment, a nationwide population-based study, Journal of Endodontics, 2014. https://doi.org/10.1016/j.joen.2014.07.007
Khalighinejad N, Aminoshariae A, Kulild JC, Williams KA, Wang J, Mickel A, The effect of the dental operating microscope on the outcome of nonsurgical root canal treatment, Journal of Endodontics, 2017. https://doi.org/10.1016/j.joen.2017.01.015
Setzer FC, Shah SB, Kohli MR, Karabucak B, Kim S, Outcome of endodontic surgery, a meta-analysis of the literature, part 1, Journal of Endodontics, 2010. https://doi.org/10.1016/j.joen.2010.08.007
Torabinejad M, Corr R, Handysides R, Shabahang S, Outcomes of nonsurgical retreatment and endodontic surgery, a systematic review, Journal of Endodontics, 2009. PMID 19567310
Kang M, Jung HI, Song M, Kim SY, Kim HC, Kim E, Outcome of nonsurgical retreatment and endodontic microsurgery, a meta-analysis, Clinical Oral Investigations, 2015. https://doi.org/10.1007/s00784-015-1398-3
Zanjir M, Lighvan NL, Yarascavitch C, Beyene J, Shah PS, Azarpazhooh A, Efficacy and safety of pulpal anesthesia strategies during endodontic treatment of permanent mandibular molars with symptomatic irreversible pulpitis, systematic review and network meta-analysis, Journal of Endodontics, 2019. https://doi.org/10.1016/j.joen.2019.09.002
Fowler S, Drum M, Reader A, Beck M, Anesthetic success of an inferior alveolar nerve block and supplemental articaine buccal infiltration for molars and premolars in patients with symptomatic irreversible pulpitis, Journal of Endodontics, 2016. https://doi.org/10.1016/j.joen.2015.12.025
Tsesis I, Faivishevsky V, Fuss Z, Zukerman O, Flare-ups after endodontic treatment, a meta-analysis of literature, Journal of Endodontics, 2008. https://doi.org/10.1016/j.joen.2008.07.016
Nixdorf DR, Moana-Filho EJ, Law AS, McGuire LA, Hodges JS, John MT, Frequency of persistent tooth pain after root canal therapy, a systematic review and meta-analysis, Journal of Endodontics, 2010. PMID 20113779
Nixdorf DR et al., Frequency of nonodontogenic pain after endodontic therapy, a systematic review and meta-analysis, Journal of Endodontics, 2010. https://doi.org/10.1016/j.joen.2010.06.020
Doyle SL, Hodges JS, Pesun IJ, Law AS, Bowles WR, Retrospective cross sectional comparison of initial nonsurgical endodontic treatment and single-tooth implants, Journal of Endodontics, 2006. https://doi.org/10.1016/j.joen.2006.06.002
Borda MF, Páez-García S, Murcia LF, Venegas-Sanabria LC, Borda MG, Endodontic treatment versus dental implant, systematic review, Acta Odontologica Scandinavica, 2025. https://doi.org/10.2340/aos.v84.43871
Méndez-Millán JA, León-López M, Martín-González J, Saúco-Márquez JJ, Cabanillas-Balsera D, Segura-Egea JJ, Antibiotic prescribing by dentists in endodontic infections, meta-analysis, Antibiotics, 2024. https://doi.org/10.3390/antibiotics13040289
Lockhart PB et al., Evidence-based clinical practice guideline on antibiotic use for the urgent management of pulpal and periapical related dental pain and intraoral swelling, Journal of the American Dental Association, 2019. https://doi.org/10.1016/j.adaj.2019.08.020
Agnihotry A, Thompson W, Fedorowicz Z, van Zuuren EJ, Sprakel J, Antibiotic use for irreversible pulpitis, Cochrane Database of Systematic Reviews, 2019. https://doi.org/10.1002/14651858.CD004969.pub5
Patel S, Wilson R, Dawood A, Mannocci F, The detection of periapical pathosis using periapical radiography and cone beam computed tomography, International Endodontic Journal, 2012. https://doi.org/10.1111/j.1365-2591.2011.01989.x
Davies A, Patel S, Foschi F, Andiappan M, Mitchell PJ, Mannocci F, The detection of periapical pathoses using digital periapical radiography and cone beam computed tomography in endodontically retreated teeth, International Endodontic Journal, 2016. https://doi.org/10.1111/iej.12500
Special Committee to Revise the Joint AAE/AAOMR Position Statement, Use of cone beam computed tomography in endodontics, Oral Surgery Oral Medicine Oral Pathology Oral Radiology, 2015. https://doi.org/10.1016/j.oooo.2015.07.033
Patel S, Brown J, Semper M, Abella F, Mannocci F, European Society of Endodontology position statement, use of cone beam computed tomography in endodontics, International Endodontic Journal, 2019. https://doi.org/10.1111/iej.13187
Murray CA, Saunders WP, Root canal treatment and general health, a review of the literature, International Endodontic Journal, 2000. https://doi.org/10.1046/j.1365-2591.2000.00293.x
British Dental Association, Root Cause, misinformation on systemic health, British Dental Journal, 2019. https://doi.org/10.1038/s41415-019-0192-z
Sebring D, Buhlin K, Lund H, Norhammar A, Rydén L, EndoReCo, Kvist T, Endodontically treated teeth and risk of a first myocardial infarction, prospective analysis, Journal of Endodontics, 2024. https://doi.org/10.1016/j.joen.2024.05.003
Sebring D, Buhlin K, Norhammar A, Rydén L, Jonasson P, EndoReCo, Lund H, Kvist T, Endodontic inflammatory disease, a risk indicator for a first myocardial infarction, International Endodontic Journal, 2022. https://doi.org/10.1111/iej.13634
Papa J, Cain C, Messer HH, Moisture content of vital versus endodontically treated teeth, Endodontics and Dental Traumatology, 1994. https://doi.org/10.1111/j.1600-9657.1994.tb00067.x
Reeh ES, Messer HH, Douglas WH, Reduction in tooth stiffness as a result of endodontic and restorative procedures, Journal of Endodontics, 1989. https://doi.org/10.1016/S0099-2399(89)80191-8
García-Espona I, García-Espona E, Alarcón JA, Fernández-Serrano J, Dental specialties recognition across Europe, BMC Oral Health, 2023. https://doi.org/10.1186/s12903-023-02987-z