Caries affects around 2.5 billion people worldwide. Yet, looking at the same radiograph, 2 dentists can propose different treatments: diagnosing a lesion and deciding when to intervene are not quite the same question.
If two dental opinions diverge, or if you want a proposed treatment confirmed, 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.
How many people are affected
| What is measured | The figure |
|---|---|
| People worldwide with a major oral condition in 2021 | 3.69 billion |
| Prevalent cases of permanent tooth caries | About 2.24 billion |
| Age band where the global burden peaks | 20 to 24, not childhood |
| Change in age-standardised prevalence in Europe | Falling, by 5.94% for permanent teeth and 9.88% for primary teeth |
| Change in the absolute number of cases worldwide | Rising, driven by demographics |
The line on age is the one that surprises most. Caries is not a childhood disease that then fades away, it is a disease whose burden peaks in early adulthood.
Caries: the threshold for intervention has moved towards more conservative treatment
For a century, the rule was to remove all carious tissue down to hard dentine. For about fifteen years, an international consensus has recommended the opposite in deep lesions, leaving softened dentine close to the pulp in place and sealing over it. The exact wording is that carious tissue is removed only to create the conditions for a durable restoration.
| What is measured | The result |
|---|---|
| Pulp exposure, incomplete against complete removal, 10 randomised trials, 1,257 patients | Odds ratio of 0.31 |
| Stepwise against complete excavation, Cochrane review | 15.4% against 34.7% pulp exposures |
| Partial against complete removal | 5% against 21.9% |
| Restoration failure | No difference, odds ratio 0.97 |
| Success at 5 years, Danish trial of 314 adults | 60.2% against 46.3% |
The effect is clear and consistent on pulp exposure. It is nil on the lifespan of the filling. So the right statement is not that this technique makes the tooth last longer, but that it avoids opening the pulp at no cost to the restoration.
Why this matters so much comes down to a single figure. In adults, once the pulp is exposed in a deep lesion, direct capping or partial pulpotomy achieves only 9% success at 5 years. In other words, opening the pulp almost always commits the tooth to a root canal. Avoiding that opening is the real stake, and it is measured.
One reservation is owed to honesty. The most cited Cochrane review on caries removal was formally withdrawn in 2019 as out of date, and the most recent network meta-analysis, covering 19 studies, finds no significant difference in overall success between techniques, with more than half the studies at high risk of bias. The evidence base is more fragile than the discourse.
Fillings: how long they last and what influences that
| What is measured | The result |
|---|---|
| Annual failure rate of posterior composites, 2,816 restorations | 1.8% at 5 years, 2.4% at 10 years |
| The same rate in a patient at high caries risk | 3.2% at 5 years, 4.6% at 10 years |
| The same rate in a patient at low risk | 1.2% at 5 years, 1.6% at 10 years |
| Variation in failure rate by practice, 359,548 restorations, 67 clinicians | From 2.3% to 7.9% |
| Variation by clinician on anterior composites, 47 clinicians | From 2% to 11% |
The patient’s caries risk carries a factor of 3. The clinician carries a factor of 3 to 5. The material carries far less weight than advertising suggests.
On the composite versus amalgam debate, the 2 results must both be given. Randomised trials favour amalgam, with a composite failure risk of 1.89, on low quality evidence and with every trial at high risk of bias. Practice-based data favour composite on large restorations, except in patients at high risk with 3 surfaces to restore. The 2 results are published, and they cover different populations and different cavity sizes.
Replacing a filling can set off a succession of more invasive treatments
This is the mechanism least explained to patients and one of the most consequential. In most published series, more fillings are replaced than newly placed, with a ratio reaching 1 to 3.8 for composite. A survey of 2,035 restorations found that 53% of restorations placed were replacements.
The most frequent reason for replacement, for every material and in every country, is secondary caries, at 56 and 59%. And that diagnosis is a visual judgement whose frequency varies with the clinician’s sex and seniority across a series of 9,805 restorations. In other words, the decision to replace depends partly on who is looking.
Preventing caries: what is genuinely demonstrated
| What is measured | The result |
|---|---|
| Fissure sealant against no sealant at 24 months, 7 trials, 1,322 children | Odds ratio of 0.12, moderate certainty |
| Translated into absolute risk if 70% of control surfaces decay | 19% with sealant |
| Fluoride varnish against placebo, 22 trials, 12,455 participants | Prevented fraction of 43% |
| Sealant against fluoride varnish, 4 studies, 1,683 children | Inconclusive, very low certainty |
| Sealing a non-cavitated lesion already present | Annual progression of 2.6% against 12.6% |
The last line runs against an old fear. Sealing over an early lesion does not trap it, it stops it, with a prevented fraction of 71.3% out to 5 years.
One product deserves to be known by international patients, silver diamine fluoride. It has been on the World Health Organization list of essential medicines since 2021. Applied twice yearly, it is the most effective intervention for arresting an advanced cavitated lesion, with moderate to high certainty. Its limit is aesthetic and it is real, it stains the lesion black. Among parents surveyed, acceptability is 67.5% on a back tooth and 29.7% on a front tooth.
Early caries between two teeth: should it be treated straight away?
A Swedish cohort followed 536 children by annual radiograph from age 11 to 22, with a remineralisation rather than a restoration strategy. The results give time landmarks that nobody gives patients.
| The stage of the lesion | Survival time |
|---|---|
| Sound surface | 75% survive 6.3 years without reaching inner enamel |
| Lesion confined to enamel | 75% survive 4.8 years without reaching dentine |
| Lesion reaching the enamel-dentine junction | 75% survive only 1.3 years, median survival 3.1 years |
| Resin infiltration against hygiene alone, 5 randomised trials | Odds ratio of 0.14 at 2 years |
The tipping point sits exactly at the enamel-dentine junction. Before it, you have years. After it, you have months. It is the only threshold that justifies a decision, and it is visible on a radiograph.
We will not write that a percentage of these lesions never progresses, because we found no primary source giving that proportion, and because the cohort above covers Swedish adolescents treated preventively, which does not transpose as such to an adult.
The cracked tooth: a typical symptom that is often misread
A crack is among the most frequent causes of unexplained pain on chewing, and it is often treated too fast.
| What is measured | The result |
|---|---|
| Share of cracked teeth that are symptomatic | 45% |
| Most frequent symptom | Pain to cold, 37%, ahead of pain on biting, 16% |
| Teeth with a visible crack that have at least one internal crack | 89% |
| Teeth placed under simple monitoring still under monitoring at 3 years, 2,858 patients | About 80% |
| Overall survival of cracked teeth at 3 years in the same study | Over 98% |
Pain on biting passes for the characteristic sign of a crack. It is in reality 2 times less frequent than pain to cold. And monitoring remains very often the right decision.
Check-ups and radiographs: frequency should follow individual risk
A long-running British trial, taken up in a Cochrane review, compared in adults a check-up every 6 months, one adapted to individual risk, and one every 24 months. At 4 years, the difference in carious surfaces is 0.15 surfaces between risk-based and 6-monthly recall, not significant, with high certainty. Between 24 months and 6 months, the difference is 0.60 surfaces, also not significant.
High certainty is rare in medicine, and here it attaches to a negative result. Six-monthly recall has not demonstrated superiority in low-risk adults. On radiographs, the American patient selection guidance sets the interval for bitewings in a recall adult with no caries at 24 to 36 months, and states that radiographic screening intended to detect disease before clinical examination should not be performed.
Whitening: what European regulation allows
The framework is precise and many people are unaware of it. Above 0.1% and up to 6% hydrogen peroxide present or released, the product may be sold only to dental practitioners, the first application of each cycle must be carried out by the practitioner or under direct supervision, and the product must not be used under the age of 18. Above 6%, it is banned in cosmetics in the European Union.
On effects, a network meta-analysis of 77 studies shows sensitivity rising with concentration, and remaining on average mild for every agent. One result deserves flagging, photoactivation by lamp or laser changes neither the risk nor the intensity of sensitivity, across 32 studies. We will not quote an absolute percentage of sensitive patients, because recent reviews report relative risks only.
Access to dental care: a large share of the population goes without or delays it
| Country | What is measured | The result |
|---|---|---|
| England | Adults seen by a public-system dentist within 24 months | 40.3% in 2024, against 50.9% in 2019 |
| England | New patients who obtained an appointment | 33%, against 83.7% for existing patients |
| France | Forgone dental care in 2022 | 8.8%, of which 5.1% for financial reasons |
| France | The same figures in 2019 | 4.9% and 2.4%, a rate that doubled in 3 years |
| European Union | Unmet need for dental examination or treatment | 4.6%, of which 2.7% for cost |
Forgone dental care is, across the European Union, almost 3 times more frequent than forgone medical examination.
What the studies do not allow anyone to claim
We will not argue that you need a check-up every 6 months, because a 4-year trial with high certainty does not support it in low-risk adults. Nothing entitles us to write that early caries between 2 teeth must be filled, because the time available before it reaches dentine is measured in years. We will not promise that one material is superior to the other, because randomised trials and practice data contradict each other.
What we will say is that the heaviest variable is neither the material nor the calendar. It is your individual caries risk, worth a factor of 3 on the lifespan of your fillings, and the person holding the instrument, worth a factor of 3 to 5.
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 possible test, but to select those that can genuinely help confirm a hypothesis, rule out a risk or guide the decision. The results are then brought together and the next steps organised. Follow-up is coordinated from there.
Request a second dental opinion
Need a medical opinion quickly? For a concern that does not call for 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 work-up pathway.
Further reading
The companion articles.
Root” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/root-canal-success-survival-and-disinformation/”>Root canal treatment, what decides its outcome
Gums” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/gums-what-bleeding-says-and-does-not-say/”>Gums, what bleeding says and does not say
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