There is a notch in my tooth at the gum line: what is it, and should I have it filled?

A non-carious cervical lesion is a loss of hard tissue near the gum line of a tooth that has nothing to do with bacterial plaque or decay. This area is more prone to wear because the enamel at the neck of the tooth is very thin and, at one point, ends altogether. The lesions usually take one of two forms: wedge-shaped or V-shaped notches with a sharp inner angle, and wider, saucer-shaped hollows with a rounded base. The classic interpretation links the wedge shape to mechanical friction and the saucer shape to acid erosion, but this too is an assumption; shape alone does not prove the cause. The systematic review cited by the study in the Journal of Clinical and Experimental Dentistry calculates an average prevalence of 46.7% in adults; the figure ranges from 9.1% to 93% depending on the study, and lesions are more common over the age of 30. The teeth most affected are the premolars.

The causes fall under three headings. The first is acid, meaning chemical dissolution that does not come from bacteria: citrus fruits and fruit juices, fizzy drinks, wine, frequently used acidic mouthwashes, and stomach acid reaching the mouth with reflux and eating disorders. Illnesses and medicines that reduce saliva make this effect worse. The second is abrasion, meaning repeated friction from outside, such as from a toothbrush and toothpaste. The third is abfraction: the hypothesis that the load of chewing and clenching flexes the tooth at the neck, and that this flexing opens microcracks in the enamel and dentine, leading to tissue loss. The review in Clinical, Cosmetic and Investigational Dentistry stresses that in most patients these three processes work together, and that a notch cannot be put down to a single cause.

The core of the abfraction debate is this: laboratory experiments and computer models show that chewing load concentrates stress at the neck of the tooth, but according to the same review, the clinical studies, which are few in number, have not been able to confirm a positive link between load and notches. Not every patient with notches clenches, and not every patient who clenches has notches. The link with factors such as premature contacts in the bite and interferences during side-to-side movements is weak. A study using optical imaging suggests that the notch is started by acid dissolving the dentine, with chewing load contributing to its progression. The review's conclusion is clear: the abfraction theory has not yet been proven.

A cross-sectional study of 245 people from Brazil shows this uncertainty in practice. Notches were found in 46.6% of participants; signs of clenching were found in 64%, wear facets in 75% and an acidic diet in 60%. None of these, however, showed a statistically significant link with having notches; a strong link was found only with being over 30. The study has its limits too: clenching was identified from indirect signs and from people's own reports, and the design is cross-sectional. Even so, a practical conclusion follows: the statement 'you have notches, so you must be clenching' is not an inference supported by evidence.

The link between notches and sensitivity is clearer. When loss of tooth structure exposes the dentine, the microscopic tubules inside it open onto the mouth, and cold, air or a toothbrush sets off a short, sharp twinge; in the Brazilian study, too, sensitivity was found to be linked with notches. The review writes that this sensitivity is often a feature of the early stage, that the tooth gradually blocks the tubules with minerals and produces reparative dentine, and that the symptoms can slowly ease. For sensitivity that does not go away, the first step is not a filling but desensitising toothpastes, fluoride varnish and treatments that seal the tubules. According to the same review, although composite or resin-modified glass ionomer fillings reduce sensitivity at first, increased sensitivity to air or cold was reported with 20% to 30% of fillings at six months.

When repair is needed, the main problem is getting the filling to stay in place. The review published in BDJ Open counts fillings in this area among the shortest-lived fillings: loss of retention, staining at the edges and poor marginal fit are common. The reasons are known: the notch has no undercut and often no enamel to hold the filling mechanically; the dentine has hardened over the years, becoming what is called sclerotic, so the adhesive struggles to bond; and moisture is hard to control at the gum margin. Nor is it clear which material is better. A 2020 meta-analysis in Heliyon found glass ionomer fillings significantly better than composite at staying in place, while a 2025 meta-analysis in the Journal of Clinical and Experimental Dentistry, pooling 18 randomised trials, found no difference between the two materials. With universal adhesives, whether or not the surface is etched with acid is reported not to change the result over 18 to 36 months of follow-up; in the only study lasting more than five years, however, the etched groups did better, and the authors rate the certainty of the evidence as low to moderate.

The most important point that gets missed in this picture is this: according to the review, there is no evidence that a filling stops a notch progressing, so a filling cannot be placed as a preventive measure. With fillings placed without addressing the cause, the lesion is seen to keep progressing and the filling to keep coming out. Nor is there an evidence-based guideline saying when notches should be repaired. Instead, the review suggests six reasons: decay starting in the notch; the edge extending below the gum and becoming impossible to clean; deep loss of tooth structure that weakens the tooth or comes close to the nerve; sensitivity that does not go away with other approaches; the tooth being due to support a denture; and the person's wish for a better appearance. For notches shallower than one millimetre that cause no symptoms and no cosmetic problem, the recommended route is monitoring every 6 to 12 months.

Notches and gum recession are often confused. As Cleveland Clinic defines it, recession is the gum pulling away from the tooth and exposing the root, and gum that has receded does not grow back. A notch, on the other hand, is a loss of structure from the tooth itself. The two are often seen together, and when they are, the plan becomes more complicated. The systematic review in the Journal of Periodontal and Implant Science reports that a notch makes the outcome of root coverage surgery less predictable and makes it more likely that the recession will return; in the studies included in the review, an average of 69% to 97% of the root could be covered, and the gum margin stayed more stable when a connective tissue graft was used. Because the methods differ so much, the authors cannot reach a firm conclusion.

This topic is about keeping individual teeth and falls within your own dentist's remit; we do not take on notch repairs or gum surgery. Teeth with notches do not in themselves mean tooth loss. The topic only concerns us if more than one tooth in the mouth has already been lost or is on the verge of being lost; in that case, what is discussed is not the individual notches but a plan for the whole jaw.

The distinction below is based on the criteria suggested in the review. Because there is no firm evidence-based guideline, the decision is made together with your dentist, looking at your own tooth.

The sequence below shows the steps generally followed for someone who has noticed a notch at the neck of a tooth. The aim is first to find the cause, then to see whether the notch is progressing.

1. 1

   A detailed history

   You will be asked how often you have acidic food and drinks, and about reflux or eating disorders, medicines that cause a dry mouth, your brushing habits, clenching, and exposure to acid fumes at work or to chlorinated pool water. This information shows how much weight each cause carries.

2. 2

   Examination and recording

   The depth and shape of the notch, whether there is decay, and how it relates to any gum recession are assessed. Wear indices such as the Smith and Knight index score the loss from 0 to 4; for example, a defect shallower than one millimetre scores 2, one between one and two millimetres scores 3, and a defect deeper than two millimetres scores 4.

3. 3

   Monitoring activity

   Standardised photographs of the inside of the mouth, study models or measurements are compared over time. In one method mentioned in the review, a very fine scratch is made on the surface, and at the next check-up the dentist looks at whether it has worn away; if it has disappeared completely or partly, the process may be active.

4. 4

   Addressing the cause

   Changes to diet and brushing habits, referral to a doctor if reflux is suspected, and measures that increase saliva are part of this step. There is no evidence that adjusting the bite by grinding the teeth down prevents notches; this is an irreversible procedure and, done inappropriately, can increase the risk of decay, wear and sensitivity.

5. 5

   Relieving sensitivity

   Desensitising toothpastes at home, and fluoride varnish or tubule-sealing treatments at the clinic, are tried. The review regards the effectiveness of lasers as uncertain.

6. 6

   The decision to repair

   If one of the reasons for repair applies, the notch is repaired while removing as little tooth structure as possible. If there is also gum recession, the review recommends placing the filling before surgery and in line with the planned gum level.

7. 7

   Questions you can ask your dentist

   How many millimetres deep is the notch, and has it been recorded? Is it active, and how will we monitor it? For what reason is repair being recommended? Which material, and why? What will be done if the filling comes out? If there is also gum recession, which will be dealt with first?

8. 8

   More than one tooth lost or at risk

   Looking after teeth with notches is your own dentist's job. If more than one tooth is already missing from your mouth or cannot be saved, send the panoramic X-ray or CBCT scan you have through the form; the dentist who will carry out the treatment reads the image, and we will reply within 24 hours. This is a preliminary assessment; the final decision is made after an examination and a CBCT scan.

Managing a notch is not just a matter of fillings, and it usually starts without one. All of these are topics to discuss with your own dentist.

With notches, both a hasty repair and neglect come at a price. These are the problems met most often.

The sequence below shows the general course for a tooth whose notch is being monitored or has been repaired. How often things are checked, and for how long, depends on the state of the tooth.

1. The first few days after a repair

   There may be slight sensitivity to cold. Keep cleaning the area with a soft brush, without pressing hard.

2. The first six months

   How the sensitivity develops is monitored. In the study cited by the review, increased sensitivity to air or cold was seen with some fillings during this period; tell your dentist if the symptoms persist.

3. Every 6 to 12 months

   For monitored notches, depth and activity are checked; for repaired teeth, the edge of the filling and how well it is holding. Photographs taken from the same angle make comparison easier.

4. Over the years

   Fillings in this area may need repairing or replacing in time. As long as the causes are kept under control, both the notched tooth and the filling last longer.

You will not find figures here. With notches at the neck of the teeth, the scope of the plan is set by these items:

How many teeth are affected

A single notch and wear spread across many teeth are not the same job; the amount of monitoring and the number of treatments and repairs vary accordingly.

Treatment without fillings, or repair

Desensitising treatments with monitoring, and fillings, differ in scope. Ask which one is being tried first.

Material and technique

Glass ionomer, composite, or techniques that combine the two need different amounts of time and material.

Whether gum surgery is needed

If there is also recession, root coverage surgery and a connective tissue graft widen the scope of the plan considerably.