A 39-year-old patient complains of a cosmetic defect, hypersensitivity of the 12, 11, 22 teeth. Objectively: vestibular surface of these teeth has oval defects with smooth shiny walls. Probing causes no pain, there is a pain reaction to cold stimuli. The defects can be stained with 5% tincture of iodine. What is the most likely diagnosis?