Due to some reasons, extrinsic and intrinsic color of the teeth may turn to yellow or brown over the time. In that case, people can resort to tooth-whitening implementations. Whitening is a chemical process applied at the dentist office or at home.
Different chemical materials are used in the process such as carbonic peroxide or hydrogen peroxide in different ratios. These materials can penetrate the porous outer layer of the teeth and break apart stain compounds by using a chemical reaction called oxidation.
If you have large fillings or crowns on your teeth, tooth whitening is not a good idea. The chemicals will only bleach your natural teeth but cannot penetrate to your dental restorations that are made of porcelain or composite material.
Tooth whitening is more effective on your yellow discoloration and can be less effective on brown or grey discolored teeth, especially when the discoloration occurred a result of exposure to tetracycline antibiotics while teeth are still developing.
There are two kinds of tooth whitening: Office beaching and home bleaching
Office bleaching is applied by the dentist at his/her office. Firstly, the gums are covered with a gel and hardened by a high-powered light. It’s a gingival barrier to protect the gums from bleaching chemicals during the bleaching. Then the dentist applies bleaching gel to the front surfaces of the teeth. The chemical penetrates into the porous outer layer of the teeth and breaks apart the stains by using a chemical reaction called oxidation. High-powered light can be used to speed up the whitening process. This procedure can be repeated two to three times for 20 minutes depending on the sensitivity the patients feel on their teeth.
Some dentists recommend professional home bleaching kit after the office bleaching in order to keep the teeth white for a longer period of time. These kits include custom made trays to fit on your teeth and tubes of whitening gel that has lower concentration of bleaching agents than the dentist used at the office. The patients use the kit as they are instructed by the dentist for a few hours at home every day or while sleeping.
The effect of the whitening can last quite a while (months to year) depending on the diet and other habits like smoking and drinking (red wine). The original color of the teeth eventually returns.