depressed oral lesions

depressed oral lesions, lesions characterized by their subsurface appearance and nonuniform shape. They may be classified as either erosions, which are considered superficial (i.e., having a depth of less than 3 mm), or the more frequently occurring ulcers, which may be up to 3 mm in depth. Ulcers may be the result of elevated lesions that have burst, and vary in appearance, with centers being yellow to gray, while the borders are typically red.