Is Composite Bonding Strong Enough to Repair a V-Shaped Notch at the Gum Line?

The wedge-shaped groove that appears where the tooth meets the gum is a common finding, usually noticed either because it catches the eye or because the area has become sensitive.

Composite is the usual answer, and it works — but this is one of the sites where restorations fail more often than elsewhere, and it is worth knowing why.

The short version is that the material is fine. The site is difficult, and the cause usually keeps operating after the filling is placed.

Will the filling hold in that position?

Composite is routinely used for these lesions and is generally the material of choice, but this location has a higher recorded failure rate than most other restorations. There are two reasons. First, the notch typically extends below the enamel onto root dentine and cementum, and bonding to those surfaces is inherently less reliable than bonding to enamel — particularly where the dentine has become sclerotic, meaning the tubules have partially mineralised and the bonding agent cannot infiltrate as effectively. Second, the cervical region flexes under biting load, and repeated flexure concentrates stress precisely at the bonded margin. So the honest answer is that composite works well here, restorations at this site do need monitoring, and the outcome depends heavily on whether the cause of the notch is addressed alongside the repair.

The current understanding is that non-carious cervical lesions are multifactorial, and attributing them to a single cause is usually wrong.

Abrasion. Mechanical wear from brushing — a hard brush, abrasive paste, horizontal scrubbing, or simply excessive force. Often more marked on the side opposite the dominant hand.

Erosion. Chemical dissolution from dietary acid, reflux, or frequent acidic drinks. This softens the surface, making it far more vulnerable to abrasion. See enamel erosion.

Abfraction. The theory that occlusal loading causes the tooth to flex, concentrating tensile stress at the cervical region and causing microscopic fracture of the mineral structure. It remains debated as a sole cause but is widely accepted as a contributing factor.

Recession. None of the above can act on the root unless it has been exposed. See receding gums.

In practice, most lesions involve a combination — recession exposes the root, acid softens it, brushing abrades it, and occlusal flexure concentrates stress at the same point.

Enamel margin. The upper edge of the lesion usually has enamel available. Etched enamel provides an excellent bond, and this margin is generally the more reliable one.

Dentine and cementum margin. The lower edge sits on root surface. Bonding here relies on infiltration of the collagen network to form a hybrid layer, which is more technique-sensitive and degrades over time through hydrolysis.

Sclerotic dentine. Chronically exposed root dentine often becomes hypermineralised and glassy. Bonding agents penetrate it poorly, and roughening the surface or using selective etching can improve adhesion.

Moisture control. The lesion often sits at or below the gum margin, where fluid seepage is difficult to exclude. Contamination during bonding is a common reason for early failure.

Material choice. More flexible flowable composites can absorb some of the cervical stress; more heavily filled microhybrids resist wear better. Combinations of the two are often used. Resin-modified glass ionomer releases fluoride and bonds chemically to dentine, and is sometimes preferred where moisture control is poor or the patient is at high risk of decay.

• Whether the cause has been identified and addressed

• Whether moisture control was adequate during placement

• Whether the margin has enamel available to bond to

• Whether the patient continues brushing aggressively at the same site

• Whether acid exposure continues

• Whether there is heavy occlusal loading on the tooth — see teeth grinding

• The depth and shape of the lesion

The most common pattern of failure is debonding at the gingival margin with the restoration remaining attached at the enamel edge, sometimes accompanied by a visible dark line or a return of sensitivity.

Monitoring only. Where the lesion is shallow, not sensitive, and not aesthetically noticeable, recording it with photographs and models and reviewing it is entirely reasonable. Not every notch needs filling.

Desensitising agents. Where sensitivity is the only complaint, fluoride varnish or a desensitising toothpaste may resolve it without restoration. See tooth sensitivity.

Resin-modified glass ionomer. Better tolerance of moisture and chemical bonding to dentine, at the cost of a less refined appearance.

Sandwich technique. Glass ionomer at the gingival margin with composite over it, combining the strengths of both.

Gum grafting. Where recession is progressing and root coverage would help. This addresses exposure rather than the notch itself.

Occlusal adjustment or a night guard. Where heavy loading is contributing. See night guards.

Brushing modification. Frequently the most valuable intervention and the one most often skipped.

• Switch to a soft or extra-soft brush

• Use small circular movements rather than horizontal scrubbing

• Hold the brush lightly — an electric brush with a pressure sensor helps

• Avoid abrasive whitening pastes on exposed root surfaces

• Rinse with water after acidic food or drink and wait before brushing

• Reduce frequency of acidic drinks rather than only the quantity

• Address reflux with your doctor if relevant

• Attend regular hygiene appointments

Arrange an assessment if:

• A notch has appeared or is becoming deeper

• The area is sensitive to cold, air, or brushing

• An existing filling at the gum line has a dark line or feels rough

• Your gums are receding — see receding gums

• You notice wear on other teeth

• You are aware of grinding or clenching

• Notches are present on several teeth

Multiple lesions in a similar pattern point to a systemic cause — acid exposure, brushing technique, or occlusal loading — rather than a local problem, and restoring them one by one without identifying that pattern tends to be unproductive. See dental check-up.

The NHS provides general information about caring for teeth and gums at nhs.uk/live-well/healthy-teeth-and-gums/take-care-of-your-teeth-and-gums/.

• Composite is the usual material for these lesions and performs adequately

• Failure rates at this site are higher than elsewhere, largely due to the bonding substrate

• Sclerotic root dentine bonds less predictably than enamel

• Cervical flexure concentrates stress at the bonded margin

• Moisture control at or below the gum line is a practical challenge

• Causes are usually multifactorial — abrasion, erosion, and occlusal loading combined

• Addressing the cause matters more than the restoration itself

Composite is strong enough for these notches. The difficulty is not the material but the site — a bonding surface that resists adhesion, a margin that is hard to keep dry, and a region of the tooth that flexes under load.

That is why the useful conversation is about the cause. Identify why the notch formed, change what can be changed, and restore it once. Restoring repeatedly without doing that is how these lesions become a recurring appointment.

If you have a notch or sensitivity at the gum line, you are welcome to book an appointment at Wimpole Dental, 22 Wimpole St, London W1G 8GQ, or call 020 7183 0692.

Dental symptoms and treatment options should always be assessed individually during a clinical examination.

This article is for general educational information only and is not professional dental advice, diagnosis, or a treatment recommendation. Information here is general and cannot replace an in-person assessment by a qualified, GDC-registered dental professional. Symptoms, suitability, fees, timelines, and outcomes vary according to individual clinical circumstances. If you have pain, swelling, or other concerning symptoms, seek prompt professional dental care. Always request a written treatment plan and cost estimate before proceeding with treatment.

Written Date: 5 August 2026

Next Review Date: 5 August 2027