The color of your teeth depends on two things: the color of the tooth dentin and the amount of translucency verses opacity that tooth enamel has, which covers this underlying Dentin. 

The color of the dentin is a yellow shade, which varies in intensity from individual to individual. This yellow color also gets darker as we age. 

If the enamel that covers the dentin is fairly translucent, then more color of the dentin shines through and the color of your teeth is darker and more yellow. Conversely, if the enamel is relatively opaque, the color of the dentin is blocked out and the teeth are whiter in appearance.

All the dental whiteners work the same way by making the enamel more opaque, thus blocking out the dentin’s color. They do this by using an oxidizing agent, carbamide peroxide, which changes the crystalline structure of the enamel, making it more opaque. The success of achieving this varies from individual to individual. Some people’s enamel will whiten very easily; others will see very little change. The procedure is very safe for the teeth. However, the teeth may occasionally become temporarily sensitive to cold. This sensitivity can be eliminated by either decreasing the frequency of the whitener applications or by stopping them all together.

As I stated, all the whiteners available use the same oxidizing agent. What varies from product to product is the concentration of the oxidizing agent and the way the agent is applied to the teeth.

On one end of the whitening dental spectrum are whiteners that whiten the teeth in one day. These are done in the dental office, involve a considerable amount of chair time, and thus are usually more expensive then other systems. The concentration of the oxidizing is pretty high which increases the potential for post op sensitivity. There is also a rebound effect with these systems. The teeth look great when you leave the office, but as much as 50% of the color returns just a few weeks later. 

On the other end of the whitening spectrum are toothpastes that contain whiteners. With these, the concentration is very low and it’s only in contact with the teeth for the short time that you’re brushing your teeth. So it would probably take years to get any noticeable results.

There are dozens of systems that fall in between these two.  

One is the many over the counter systems available. These can work very well. The main drawback is that the delivery system usually involves applying a strip to your teeth. Getting the strip to adhere to the teeth and getting the strip to touch the surfaces in between your teeth can be problematic. The currently available systems have made considerable improvements in the adherence problem.

I have had the best success by offering a whitening at-home system. An impression is taken of your teeth from which a custom tray for applying the agent is made. The agent is placed in this tray at home and left in the mouth for one hour. This system gives excellent results after about 10 to 20 applications.

Whether you use a custom tray or an over the counter system, I suggest doing the upper teeth first before doing the lowers. This is because the change occurs slowly and it’s difficult to see the change day to day. By doing the uppers first, you can compare these with your lower unchanged teeth to see how effectively the whitener is working.