Teeth whitening is effective on natural tooth enamel, but it won't change the color of dental restorations like crowns, veneers, or fillings. If your natural teeth become lighter, but your restorations stay the same shade, there could be a noticeable difference in color. If you have multiple restorations, your dentist can discuss options for maintaining a uniform look, such as replacing older restorations to match your newly whitened teeth.