Tetracycline is an antibiotic commonly used to treat young people for acne. From the 1950s until 1980, it was given to children. The age is significant, since tetracycline will deposit in teeth that are still forming, leaving a dark stain that can be striated or cover the whole tooth. Tetracycline administration before the age of 8 is no longer done. The stains are medically harmless but unsightly. Teeth whitening is an insufficient treatment, since the stains are deeply embedded in the tooth enamel. Instead, (translucent) veneers are the standard approach to cover the stains.
Find a dentist with experience in veneers to hide tetracycline stains. This is actually not so easy. You may want to go directly to a cosmetic dentist.
Attempt teeth whitening (with the traditional carbamide peroxide) if your case is mild (it does not go deep into the tooth). According to Dr. David Hall, you should insist on dentist-supervised, at-home tooth whitening, where you can take the trays home and do it yourself. The cost savings over having the doctor do it for you in the office is tremendous.
Have veneers cover up stained teeth in the front of the mouth. The dentist will cement them in place after shaping the teeth a little.
Have a dental crown made to cap the surface of any back tooth that is particularly stained.