Abfraction

Definition

Abfraction is a proposed mechanism for hard-tissue loss in the cervical region. Under this hypothesis, named by Grippo in 1991, repeated off-axis occlusal forces cause the tooth to flex, and the resulting tensile and compressive stress concentrates in the cervical region — the narrowest part of the tooth. This stress can micro-fracture the bond between hydroxyapatite crystals and enamel rods at the CEJ, making the tissue more vulnerable to removal by erosion and abrasion. The main support for this model comes from finite element analysis studies and laboratory work.

Concept Boundary & Misconceptions

The most important point is that abfraction is not on the same footing as the other three wear mechanisms. Attrition, abrasion, and erosion are documented mechanisms; abfraction is a hypothesis for which conclusive clinical evidence establishing it independently as a cause has not yet been provided, and systematic reviews have been unable to confirm a causal relationship between occlusal factors and cervical lesions. FEA models show that stress concentration may occur, but a mechanism being possible is not the same as it being proven.

The second misconception is conflating abfraction with NCCL. NCCL is a clinical finding; abfraction is a proposed explanation for part of it. Calling every wedge-shaped lesion "abfraction" means concluding, from the lesion's shape alone, an unproven cause.

The most dangerous form of this misconception is the third: moving from an abfraction diagnosis to occlusal adjustment. Occlusal adjustment is an irreversible intervention on healthy tissue, and performing it to "treat" a lesion whose cause hasn't been proven is grinding a tooth based on a hypothesis.

Role in Clinical Decision-Making

The practical place for abfraction is as a possible contributing factor, not as a diagnosis that by itself creates a treatment indication. What should be done is managing the documented factors: controlling the acid source, correcting toothbrushing technique and tools, and, in a bruxer patient, protecting the structure with a splint. If a cervical restoration is indicated, choosing a material with a lower modulus of elasticity and accepting that tooth flexure may play a role in restoration failure is reasonable — but this, too, doesn't turn the hypothesis into certainty.

Abfraction is a clear example of the cost when a conceivable mechanism becomes a routine diagnosis. The explanation we have for the cause must not outrun the evidence we have for it — especially when the treatment that follows from it is irreversible.