About 37% of people have at least 1 impacted wisdom tooth. That is common, and it does not automatically mean an operation is needed: pain, infection, damage to the neighbouring tooth, position and imaging are what determine the indication.
If a wisdom tooth, jaw pain or a proposed cone beam scan is worrying you, 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.
The asymptomatic wisdom tooth: little evidence for routine preventive extraction
We have to start with the volume of evidence, because it is astonishing. The reference Cochrane review, updated 4 times since 2005, retained only 2 studies in total, 493 participants, to compare removal and retention of an impacted, disease-free wisdom tooth.
| What is measured | The result |
|---|---|
| Number of studies reporting quality of life, the review’s primary outcome | None |
| Caries on the adjacent surface of the second molar | Risk ratio of 0.69, not significant, very low certainty |
| Incisor crowding at 5 years | A difference of 0.30 mm, of no clinical consequence |
| The authors’ own wording | The evidence is insufficient to determine whether these teeth should be removed or retained |
The reference British guidance is more direct still. It asks that prophylactic removal of pathology-free wisdom teeth be discontinued in the public system.
A randomised trial adds a further element, this time from the orthodontic side. Across 164 randomised patients and 77 reviewed after a mean of 66 months, removing wisdom teeth reduces the increase in incisor crowding by 1.1 millimetres against 2.1, a difference that is neither statistically nor clinically significant. The authors conclude that extraction to prevent crowding cannot be justified.
Complications, by contrast, are quantified. In a meta-analysis of 24,985 patients and 32,866 teeth, temporary lingual nerve injury affects 1.24 to 2.44% of procedures depending on technique, and permanent injury 0.07 to 0.28%. One result runs against intuition. The lingual retractor, whose purpose is to protect the tongue, multiplies the risk of temporary injury by 4.8.
Cone beam CT: a radiation dose worth knowing
| The examination | Effective dose |
|---|---|
| Intraoral periapical film | Under 1.5 microsieverts |
| Dental panoramic | 2.7 to 24.3 microsieverts |
| Dentoalveolar cone beam | 11 to 674 microsieverts, median 61 |
| Craniofacial cone beam | 30 to 1,073 microsieverts, median 87 |
| Multislice CT | 280 to 1,410 microsieverts |
The gap between a periapical film and a large-field cone beam can reach a factor of 700. The mean annual natural background dose in the United Kingdom is about 2,700 microsieverts, which gives the scale.
One point deserves to be flagged to parents. In the reference dosimetric meta-analysis, the dose of a small-field cone beam in a child, 103 microsieverts, is higher than that of the same examination in an adult, 84 microsieverts. A smaller format does not mean a smaller dose.
European guidance is unambiguous on indication. A cone beam must be justified individually, and routine or screening imaging is described there as unacceptable practice. We found no published audit quantifying the share of unjustified cone beams, and we will therefore not quote a percentage on that point.
The jaw joint: start with the least invasive treatments
A gap in prevalence must be explained before any figure. Clinical signs of temporomandibular disorder affect 31.1% of adults, while population surveys find about 5% of self-reported symptomatic cases. These are not 2 contradictory figures, they are 2 different things, the detectable sign and the case that hurts.
As for the course of the disorder, a reference cohort finds that 49% of first episodes are still present at 6 months, and that 27% of those persisting at 6 months no longer have the disorder at 7 years. The picture is one of fluctuation, not linear worsening.
On occlusal splints, the most recent Cochrane review covers 57 randomised trials and 2,846 participants, of which a single study is at low risk of bias. Its conclusion is that certainty is very low for every comparison and every outcome, and that discomfort and recurrence rate are reported by no study at all. Rarely and tellingly, the older Cochrane review devoted to stabilisation splints has been withdrawn.
The American dental research institute sums up the approach in a phrase we take up as it stands, less is often best. And it explicitly advises against treatments that permanently alter the teeth or the bite, crowns, grinding, repositioning orthodontics, stating that they do not work and can worsen the problem. On joint prostheses, the American medicines authority received 680 adverse event reports between 2014 and 2018, for about 5,500 prostheses placed over the preceding decade.
One last point deserves to be known, because much circulates in the opposite direction. A prospective cohort of 1,018 people followed 20 years, from age 11 to 31, finds no association between orthodontic treatment and the onset of a joint disorder, nor with a persistent one. The purely occlusal model of these disorders has in fact been replaced by a biopsychosocial model in current literature.
Oral cancer: what a randomised screening trial showed
A cluster randomised trial in Kerala covering nearly 200,000 people tested visual inspection of the oral cavity. The result is this.
| Population | The mortality result |
|---|---|
| General population | Mortality ratio of 0.79, not significant |
| Tobacco or alcohol users | 0.66, significant |
| Male users | 0.57, significant |
| Share of positive screens who attended the next appointment | 63% |
The last line is the one to remember. About 4 people in 10 who screened positive never completed the pathway. A screening programme is worth what the circuit behind it is worth, not what the test is worth.
The US task force grades oral cancer screening in primary care as grade I, insufficient evidence, with the sensitivity of visual examination reported between 18% and 94.3% across studies. One qualification matters, that assessment covers primary care and does not include examination by a dentist.
Sleep apnoea: the oral appliance can help despite a more modest physiological effect
Across 77 randomised trials, continuous positive airway pressure reduces the apnoea index by 25.4 events per hour and the mandibular advancement device by 9.3. The machine is clearly more efficacious, that is not in dispute.
A crossover trial of 126 patients adds the missing datum. On positive pressure the index falls to 4.5 per hour against 11.1 with the device. But adherence is 6.50 hours per night with the device against 5.20 hours with the machine. As a result, 24-hour blood pressure is identical between the 2 treatments, to within 0.2 mmHg. The machine’s greater efficacy is offset by its lower use. It is one of the rare demonstrations this clear that theoretical efficacy is not real-world effect.
Jaw surgery: when a surgical correction becomes necessary
When the discrepancy between the jaws is too great to be compensated by moving teeth, surgery becomes the only route. Its best measured functional result is not about appearance but about breathing at night.
| What is measured, advancement of the 2 jaws for sleep apnoea | The result |
|---|---|
| Reduction in the apnoea index, 45 studies, 518 patients | Minus 47.8 events per hour, a fall of 80.1% |
| Share of patients improved | 98.8% |
| Surgical success, more than halved to under 20 events per hour | 85.5% |
| Cure, index under 5 | 38.5% |
| Share of patients who had already had other apnoea surgery | 73.5% |
The last line matters. These results were obtained in patients for whom other approaches had failed, which makes the figure more striking still, and which forbids transposing it to an unselected population.
On skeletal relapse after this kind of surgery, we found no recent quantified meta-analysis. The available sources are qualitative, and we will therefore not give a percentage.
What the studies do not allow us to claim
You will not read here that a wisdom tooth causing no trouble should be removed, because the evidence does not exist. We will not claim that it should never be removed, because recurrent infection around the crown is a recognised indication. Nothing entitles us to write that a splint cures jaw pain, because 57 randomised trials give very low certainty.
What we will say is that none of these procedures should be offered without the person knowing how much evidence there is behind it, and that in several cases the honest answer is very little.
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.
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.
Caries” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/caries-the-most-widespread-and-the-least-well-decided/”>Caries, the most widespread disease
What” rel=”noopener” target=”_blank”>https://noriahealth.com/blog/what-one-night-of-recording-actually-measures/”>What one night of recording actually measures
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