This patient had been prescribed an antibiotic called tetracycline when she was a child.  Unfortunately, it was unknown at that time that the drug would be incorporated into the teeth and cause a dark gray coloring.  A technique called bonding was used in her case.  In bonding, the white composite material that is used for filling cavities in front teeth was layered onto the front of her teeth.  As you can see the results look great initially, however, the technique is not very permanent, and must be redone periodically.  This technique has now been replaced by porcelain laminates.