What causes a yellow defect on the facial surface of anterior teeth?

A yellow defect on the facial surface of anterior teeth is typically associated with abrasion. Abrasion occurs when there is mechanical wear of the tooth structure due to factors such as aggressive tooth brushing, the use of abrasive toothpaste, or external substances. This wear can lead to a loss of enamel, exposing the underlying dentin, which is naturally yellow in color. As a result, the affected areas present a yellowish appearance on the teeth.

In contrast, prolonged exposure to fluoride generally leads to fluorosis, which can cause white spots or a mottled appearance rather than a distinct yellow defect. Trauma may result in discoloration of a tooth but usually does not lead to a singular yellow defect; it can cause a range of color changes, including darkening. Caries, or tooth decay, can lead to varying discoloration but is typically associated with brown or dark areas rather than yellow defects specifically. Thus, abrasion is the most accurate answer when specifically considering the yellow defect on the facial surface of anterior teeth.