While teeth whitening procedures in most cases produce highly satisfying results, not every type of stain or discoloration responds well to one. First of all, a teeth whitening procedure only works on natural teeth and does not change or improve the color of dental fillings, crowns, or bridges. It should also be mentioned that just as individuals with yellow tones to their teeth typically respond well to a teeth whitening, brown and grayish teeth can respond less well and may require more intensive whitening regimens or alternative cosmetic treatments. Furthermore, a teeth whitening procedure may not be recommended in the presence of sensitive teeth, worn enamel, and significant gum disease.