Abfraction is a type of tooth wear that creates small notches or grooves near the gum line, typically on the outer-facing surface of a tooth. Unlike cavities, these lesions aren’t caused by bacteria. They’re thought to result from mechanical stress on the tooth, particularly from heavy or off-center biting forces that cause the tooth to flex slightly at its thinnest point near the neck.
How Abfraction Develops
The theory behind abfraction centers on what happens when a tooth absorbs force that isn’t directed straight down its long axis. During grinding, clenching, or chewing with a misaligned bite, lateral forces push against the crown of the tooth. Because a tooth has some natural elasticity, it flexes ever so slightly. That flexing concentrates stress at the cervical area, the narrow zone where the crown meets the root, right at the gum line.
The enamel in this cervical region is already thinner and structurally weaker than enamel elsewhere on the tooth. Under repeated stress, microscopic cracks form, and tiny pieces of enamel and the underlying layer begin to break away. Over time, a visible notch develops. This process can accelerate significantly when grinding or clenching forces act repeatedly over months and years, especially during sleep when bite forces can be stronger than during normal chewing.
It’s worth noting that the abfraction theory remains scientifically debated. Research correlating the progression of these lesions to occlusal forces has not provided conclusive evidence to confirm or rule out the role of biting stress alone. Most dental researchers now view these cervical lesions as multifactorial, meaning that mechanical stress likely works alongside abrasion (from aggressive brushing, for example) and erosion (from acidic foods and drinks) to produce the damage. The two widely accepted mechanisms for non-cavity cervical lesions remain erosion and abrasion, with abfraction acting as a potential contributing or amplifying factor.
What Abfraction Looks Like
Classic abfraction lesions appear as wedge-shaped or V-shaped notches on the outer surface of a tooth, right at the gum line. They tend to have sharp, clearly defined edges. In some cases, the lesion looks more like a shallow C-shape with a rounded floor, or a broader saucer shape. The appearance often depends on whether erosion or abrasion has also been at work: acid exposure and brushing wear tend to soften the sharp angles and widen the notch into something smoother and more dish-like.
Dentists grade these lesions by depth. A mild lesion is 1 mm deep or less and typically V-shaped with a sharp angle. A moderate lesion reaches 1 to 2 mm deep and often takes on a more saucer-like shape. Severe lesions exceed 2 mm in depth with a wide, rounded profile. Premolars and incisors are the most commonly affected teeth, and lower premolars tend to develop these lesions more often and more severely than upper premolars.
Common Symptoms
Small abfraction lesions often cause no symptoms at all, and many people first learn about them during a routine dental exam. As the notch deepens, however, it exposes the softer inner layer of the tooth beneath the enamel. This exposed layer contains microscopic tubes that connect to the tooth’s nerve, which is why sensitivity to cold, heat, sweet foods, or even a blast of air becomes the most noticeable symptom. You might also feel a distinct groove or ledge when you run your tongue or fingernail along the gum line of the affected tooth. Food can pack into deeper lesions, causing irritation to the surrounding gum tissue.
Causes and Risk Factors
Several overlapping factors contribute to abfraction:
- Teeth grinding and clenching (bruxism): Nighttime grinding is one of the most frequently cited risk factors. The repeated lateral forces flex the tooth at its weakest point. In one clinical study, 16% of patients with abfraction lesions reported nocturnal bruxism.
- Misaligned bite: When teeth don’t meet evenly, certain teeth absorb disproportionate force during chewing. These off-axis loads concentrate stress at the cervical area.
- Aggressive brushing: Hard-bristled toothbrushes or a heavy hand can physically wear away enamel at the gum line, especially once stress cracks have already weakened the surface.
- Acidic foods and drinks: Citrus, soda, wine, and other acidic substances soften enamel, making it more vulnerable to mechanical damage from both biting forces and brushing.
These factors rarely act in isolation. A person who grinds their teeth at night, brushes aggressively in the morning, and drinks acidic beverages throughout the day is creating a three-pronged assault on the cervical enamel. The combination tends to produce faster, deeper lesions than any single factor alone. Research consistently emphasizes that the most important interaction is how erosive acid damage makes teeth far more susceptible to wear from abrasion.
How Abfraction Differs From Other Tooth Wear
Abfraction is one of four types of non-cavity tooth wear, and they’re easy to confuse because they often overlap on the same tooth. Abrasion is physical wear from an external object, most commonly a toothbrush. It tends to produce broad, flat, polished grooves along the gum line, particularly on the side of the mouth opposite your dominant hand (since you apply more pressure there). Erosion is chemical dissolution from acids, whether from diet, acid reflux, or frequent vomiting. It creates widespread, shallow, cupped-out areas that can affect any surface of the tooth. Attrition is wear from tooth-on-tooth contact, visible as flat, shiny spots on the chewing surfaces.
Abfraction’s distinguishing feature is supposed to be its sharp, V-shaped profile concentrated at the gum line, driven primarily by stress rather than direct contact or chemistry. In practice, though, most cervical lesions involve some combination of all these processes, and even experienced dentists can find it difficult to determine exactly how much each factor contributed.
Treatment Options
Not every abfraction lesion needs active treatment. When lesions are shallow (less than 1 mm), aren’t progressing, and aren’t causing sensitivity, monitoring every 6 to 12 months is a reasonable approach. Your dentist will measure the lesion’s depth over time to check whether it’s stable or worsening.
For lesions that are deeper, sensitive, or at risk of further damage, a tooth-colored filling material is placed into the notch to restore the tooth’s shape and seal off the exposed inner layer. The procedure is similar to getting a small filling: the surface is prepared with a mild conditioning agent, an adhesive layer is applied, and the restorative material is sculpted into the notch, then shaped and polished smooth. It’s typically done without numbing for shallow lesions, since the work stays near the surface.
Addressing the underlying cause matters just as much as fixing the notch itself. If grinding or clenching is a factor, a custom-fitted mouthguard (sometimes called an occlusal splint or night guard) can reduce the forces that flex the tooth. These are usually made from a soft, flexible thermoplastic material about 1.5 mm thick, molded to fit your teeth precisely. Wearing one consistently at night protects both the natural tooth structure and any restorations from excessive bite forces.
If a misaligned bite is directing force unevenly onto specific teeth, your dentist may suggest minor adjustments to the biting surfaces to distribute pressure more evenly. Switching to a soft-bristled toothbrush and using gentle, circular brushing motions rather than aggressive back-and-forth scrubbing helps prevent further mechanical wear. Reducing intake of acidic foods and drinks, or at least rinsing with water afterward, limits the erosive component.
Can Restorations Fall Out?
Fillings placed in abfraction lesions have a higher failure rate than typical cavity fillings. The location is challenging: it’s right at the gum line where moisture control is difficult, and the ongoing flexing forces that caused the lesion in the first place can stress the bond between the filling material and the tooth. This is precisely why managing the bite forces with a night guard is so important. Without addressing the root cause, you may find yourself replacing the same filling repeatedly. When a mouthguard is used alongside the restoration, the filling is significantly more likely to stay intact long-term.