Final answer:
Black thin lines on the cervical third of the teeth are extrinsic stains often caused by the consumption of tannin-rich foods like tea, coffee, and red wine. Good oral hygiene can prevent and reduce these stains.
Step-by-step explanation:
Black thin lines on the cervical third of the teeth are commonly associated with the consumption of tannin-rich foods and beverages. These lines are essentially extrinsic stains that result from the deposition of tannins found in items such as tea, coffee, and red wine. These colorful compounds have the ability to adhere to the dental enamel and infiltrate the microscopic pits and grooves, particularly in the cervical area where the enamel may be thinner and rougher.
It is important to maintain good oral hygiene practices to prevent and reduce the formation of such stains, including regular brushing, flossing, and professional dental cleanings. Regular gynecological examinations can help identify cervical erosion and determine the appropriate treatment if necessary.