Abrasion is wear from which of the following?

• A. Tooth-to-tooth wear
• B. Chemical dissolution (acid)
• C. Mechanical stress causing microfractures at cervical areas
• D. Wear from external objects (e.g., toothbrush)

Answer: (D)

Abrasion is the loss of tooth structure caused by external mechanical action. It’s distinct from attrition, which is wear from tooth-to-tooth contact, and erosion, which is chemical dissolution from acids. The classic example is wear from an external object rubbing against the tooth, such as a toothbrush or gritty toothpaste. That external mechanical wear, often seen at the cervical areas of teeth, is what defines abrasion. The other options describe attrition (tooth-to-tooth wear), erosion (acid dissolution), and abfraction (microfractures from flexural stresses at the cervical area), respectively.