Sensitivity Problems

      A normal response during teeth whitening 

Some patients may experience increased tooth sensitivity to cold during the treatment, while others may have nonspecific sensitivity in their teeth, gums, tongue, lips or throat.  If any of these symptoms occur and are more than mild, discontinue the treatment until you speak with your dental professional.. The symptoms should subside within 1-3 days after interrupting the treatment.   11
 When the sensitivity is gone, consider the following options.  If the problem is gum irritation, reduce the amount of gel used in your trays. Also, place your trays on your teeth and visually examine them.  If the trays extend over your gums, have your dental professional trim them to prevent the gel from getting on your gums.   
  If the sensitivity is in the teeth, try whitening every other or every third night.  If the sensitivity persists, ask your dental professional for Tooth Mousse®, a desensitizing gel to be used in conjunction with the whitening gel.  Again, if the discomfort continues, discontinue the treatment and consult your dental professional.  
 It is normal to see dark colour in the trays where you have amalgam (silver) fillings.  The gel oxidizes the surface stains on theses amalgam fillings.  The area of the tooth closest to the gums may take longer to lighten than the biting edge.  It will also remain the darkest part of the tooth.   
  Why do the teeth become sensitive? 
When the whitening gel(hydrogen peroxide or carbamide peroxide) is broken down it forms oxygen molecules, which create the bleaching process by breaking down the stained molecules. Oxygen is good for healthy gums and tissue, but is also responsible for the sensitivity in some patients. These oxygen molecules are absorbed by the tooth’s nerve, which sometimes cause a sensitive feeling.  The faster the uptake of oxygen, the more likely the chance for sensitivity. Higher concentrations on peroxide ussually means a more rapid uptake of oxygen. When the whitening is stopped, oxygen uptake ceases and any symptoms disappear.
How long does the sensitivity lasts?
When the direct contact between gel and tooth is stopped, oxygen uptake ceases and the sensitivity goes away. This ussually happens within minutes after the trays are removed from the mouth. In some individuals some form of sensitivity might come and go for up to 3 days after whitening. 
Will the whitening damage my teeth?
No. The structure of your teeth will stay the same or return to normal once the treatment is discontinued. The active ingredient hydrogen peroxide or carbamide peroxide is broken down into water and oxygen that is harmless to your teeth.      
My teeth are generally sensitive to begin with. Can I still whiten my teeth?
The answer is Yes and No. Since your teeth are already sensitive to begin with, the chances that it will become more sensitive is very high. However, since you are in absolute control of the process (you can remove the tray if you want to at any time) you can decide if you can do it or not. Your dentist will also be able to help you decide if it is a good option for you or not.      
What can I do if I experience sensitivity?
Try to whiten only once a day or even every alternative day. This will slow the whitening process down, but will help minimise the sensitivity. Your whitening will obvously just take longer to complete.
You can also try taking over-the-counter ant-inflammatory drugs such as ibuprofen or paracetamol 1 hour prior to whitening.
If the sensitivity persists, ask your dental professional for some desensitising agents such as Tooth Mousse®,  fluoride gel or Relief®.  These products can be used in the whitening tray prior or after your whitening sessions to desensitise the teeth. Again, if the discomfort continues, discontinue the treatment and consult your dental professional.