According to the Herman Ostrow School of Dentistry of USC, dental abrasion occurs when mechanical forces from an external object lead to the loss of tooth structure. In this scenario, excessive brushing with a toothbrush can erode the tooth enamel, eventually affecting the softer dentin and cementum layers. Signs of abrasion include worn, shiny areas on the tooth surface, often accompanied by yellow or brown spots near the gumline. Additionally, notching—a wedge or V-shaped indentation along the gumline—may also indicate dental abrasion.