Tooth Whitening/ Dental Bleaching is a common procedure in Cosmetic Dentistry. Teeth may get discoloured because of many reasons like drinking tea, coffee, and smoking. Teeth become darker as a result of ageing also due to change in structure and composition of tooth. Bleaching is done most effectively on these types of stains. Other types of stains are result of some drugs like tetracyclines or excessive fluoride during the tooth forming time.
Tooth-whitening works best for people with yellow teeth and is less effective for people with brown teeth. If your teeth are grey or purple, tooth bleaching probably won't work at all. These result in grey/ black discolorations which are difficult to successfully whiten by dental bleaching alone. The other options for such type of cases are Veneers (Composite & Ceramic), Crown/ Cap (in very severe cases) etc.
In-office Bleaching systems contain from 15% to 43% Hydrogen-peroxide.
Dental Bleaching is not harmful for you if done with proper care & good quality Bleaching Material including adequate gums protection. You may feel little sensitive only for 1st few days after bleaching which is normal and will subside on its own.
After Bleaching, you can maintain the results for longer duration by brushing, flossing, and rinsing daily. Also, avoid (at least reduce) acidic and stain causing foods and beverages such as Black teas and coffee, Carbonated beverages (sodas etc.), Sauces (soy, tomato etc.).