A 26-year-old woman, who works with chemical substances at a factory, came to a dentist with complaints of teeth discoloration and extreme sensitivity to cold, sweet, and sour foods in her upper front teeth. Objectively, on the vestibular surface of teeth 13, 12, 11, 21, 22, and 23, at their equator, there are white spots that spread to the cutting edges. Probing detects rough and fragile enamel in the affected areas. Vital staining is positive. Make the clinical diagnosis: