Patient-friendly definition from the DentistsDirectory.org dental glossary.
Abrasion is the wearing away of tooth structure caused by mechanical forces rather than bacterial decay. The most common cause is aggressive tooth brushing — pressing too hard or using a stiff-bristled brush gradually scrubs away the relatively soft root surface and enamel near the gum line. Other causes include habitually chewing on pen caps or fingernails, using your teeth as tools, or regularly using highly abrasive whitening toothpastes.
Abrasion most commonly appears as a V-shaped or notched groove near the gum line on the outer surface of the tooth. The exposed area often looks yellowish because it is dentin rather than the white enamel above it. Affected teeth are frequently sensitive to cold water, sweet foods, or direct touch at that spot.
Mild abrasion is often monitored rather than immediately filled. For sensitive or deeper grooves, composite resin bonding can protect the exposed dentin and restore the tooth's contour. More importantly, your dentist will address the underlying cause — typically recommending a soft-bristled brush, lighter pressure, or a less abrasive toothpaste. Switching to an electric toothbrush with a pressure sensor is one of the most effective changes for chronic over-brushers.