A 48-year-old woman complains of itching gums and increased teeth sensitivity to thermal and chemical stimuli. Objectively, the dental cervices are exposed. The gums are firm and pale. There is a small amount of supragingival dental plaque. In the area of teeth 13, 14, 24, and 25 there are cuneiform defects, probing of which is painful. The woman was provisionally diagnosed with periodontosis. What X-ray presentation is characteristic of this disease?