This is so because in-office bleaching methods have more bleaching concentration than that which is offered over the counter thereby producing faster results. In-office tooth bleaching is also the safest. Unlike tooth whitening done at home, in-office whitening is conducted and monitored by a professional practitioner. The polishing action is important as this will remove the plaque and dirt found at the surface of the teeth. The mouth will then be isolated with the use of the gauze. This is a necessary step so that the teeth will be dry for the rest of the procedure. There will be times when the retractors will be used as well, and this is important so that your lips and tongue will not get in contact with the whitening agents incorporated in the solution. For this set of bleaching agents, the usual recommendation is to use twice daily and the waiting time can reach two weeks before the effects can be realized. In terms of price, expect to pay $3 to $10 for teeth whitening toothpastes. And for other bleaching formulations, some over the counter products can fetch around $30. What it contains are silica for example and some aluminum and calcium that will be enough to remove stains but not really to counter the natural discoloration of the teeth as it ages nor does it contain substances that react with the mineral structure to whiten a dark colored teeth. Second, most tooth bleaching agents such as gurgles and gels contain peroxide. Over the counter teeth whitening has in a short period of time claimed that. In fact it sparked controversies among dentists, but more to that later. Even as professionally supervised teeth whitening treatments contain hydrogen peroxide as its active bleaching agent that is safe enough even for home use, over the counter preparations contain carbamide peroxide which is even safer and milder. It also causes the edges of the tooth shade darker, faster. Another big factor is smoking. Nicotine is brownish in color that could stick in the enamel of the tooth and even soak in its structure causing internal discoloration. Red wine may be good for the heart but it contains a high concentration of tannins that causes staining fast.