The Difference between Internal and External Tooth Bleaching

External tooth bleaching (or whitening) is accomplished in a couple of different ways. The first of which is to have your dentist take impressions of your teeth so that custom trays (specifically for bleaching) can be made. When the trays are completed, you will be given the trays and a bleaching kit to take home so that you can bleach your teeth at home. The instructions on how to do this will be explained to you by the dentist or the dental assistant.

Depending on the bleach kit or product that is offered by the dentist, the instructions regarding usage will vary. What remains the same is that you will fill your custom trays with the bleaching material and wear them anywhere from five minutes at a time to as much as three hours or overnight. This process takes approximately five to seven days of consistent use to achieve the desired results. The results will vary from person to person. There is also a point at which the teeth will no longer continue to lighten. It is not uncommon to achieve two shades lighter than your current shade.  

External Bleaching

External bleaching can cause the teeth to become sensitive; this is usually mild, but sometimes it can cause extreme sensitivity, in which case your dentist may recommend that you refrain from bleaching for a few days and/or use a desensitizing toothpaste. Another method of external bleaching is performed entirely in the dental office. This process takes about an hour from start to finish. While you are seated in an operatory chair the bleaching compound is placed directly on your teeth after some preparation to protect your lips and gum tissue. A high intensity light is directed at your teeth for approximately 30 minutes. This process can also be combined with a take home bleach kit with trays depending on the dentist's recommendation. The in-office bleaching procedure will give more immediate results.                                                                                     

Internal Bleaching                                                         

Internal tooth bleaching is a completely different process that requires access inside the tooth. This type of bleaching is done when a particular tooth is darkened or discolored; this usually occurs when the nerve inside the tooth has died due to either infection or trauma. When this occurs, a root canal procedure is completed to remove the nerve from inside the canal of the tooth.  Prior root canal therapy facilitates access to the center of the tooth (pulp chamber) where the internal bleaching material is placed. A cotton pellet is soaked in the bleaching compound and placed in the center of the tooth and covered with a temporary filling material to seal the opening. 

The patient keeps this material inside the tooth for approximately one week and then returns to the dental office to assess the results of the bleaching. This procedure normally needs to be repeated a few times until the desired result is met. No anesthetic is needed for this procedure because the nerve has already been removed from the tooth, therefore the tooth has no feeling in it. There is one initial charge for the internal bleaching procedure and any repeat procedures are included in the initial cost. The results are very favorable.