Tooth Wear

Definition

Tooth wear refers to the progressive loss of enamel and dentin without any caries or trauma being involved. Four mechanisms have been described for it.

Attrition results from tooth-to-tooth contact, abrasion comes from mechanical wear by a foreign object such as a toothbrush, erosion comes from chemical dissolution by acid, and abfraction is a hypothesized mechanism for tissue loss in the cervical region under occlusal flexural stress.

Concept Boundary & Misconceptions

In most patients, a single mechanism is not acting alone; usually two or three of them act together on one surface. For this reason the most common mistake is to immediately label every instance of wear as "attrition from bruxism." The diagnosis has to be read from the shape of the lesion, not merely from the presence of wear.

Cupping is a shallow, bowl-shaped depression on the occlusal surface, most often at the cusp tips. The dentin at the center of the lesion is softer than the surrounding enamel and is lost faster, so the center hollows out and a raised enamel rim remains around it. Cratering is the same pattern with a larger, deeper opening that can occupy a wider portion of the occlusal surface instead of a single cusp.

What distinguishes these two from pure attrition is the bowl-shaped, dentin floor sitting lower than the surrounding enamel rim. Pure attrition produces a flat, shiny facet that mates with the opposing tooth, not a hollow. So a bowl-shaped floor means erosion is also involved, and cupping/cratering are effectively the signature of combined attrition and erosion, not bruxism alone. A wedge-shaped lesion at the gumline, by contrast, points more toward abrasion or abfraction. A hasty label sends treatment down the wrong path as well.

Abfraction itself remains debated. Unlike the other three mechanisms, which are well documented, its existence as an independent mechanism has not been settled in the literature and it is usually discussed alongside abrasion and erosion. One other point is often missed: some wear is normal with increasing age. The problem begins where the rate of wear outpaces the body's compensatory rate (such as compensatory eruption).

Role in Clinical Decision-Making

Before any decision, the dominant pattern must be identified, and whether active intervention is even needed or whether the process should simply be monitored with study models, photographs, and an index such as BEWE. The choice between an additive restoration and a reductive one, or the need to increase vertical dimension in severe cases, all trace back to this same diagnosis.

The most important point, and the one most often missed, is this: if the acid source (in erosion), the parafunctional force (in attrition), or the faulty brushing technique (in abrasion) is not controlled, any restoration placed on these surfaces will wear or fracture at the same rate as before.