How whitening actually works
Inside the tooth, not on it. Understand this and half the client questions answer themselves.
What you will learn
- Why whitening happens in the dentin and not on the surface
- What the first session really does
- Why teeth look whiter at first and then settle
It happens under the enamel
Whitening takes place in the dentin, the layer beneath the enamel. The peroxide has to travel through pores in the enamel to reach it. Those pores have to be opened before anything can get through.
- The first application of gel opens the pores in the enamel.
- Later applications reach the dentin and release oxygen molecules.
- Those oxygen molecules break down the stain.
That is the whole reason the treatment is three rounds and not one. The first round is largely doing the opening.
Whitening against dehydration
The same pores that let peroxide in let water out. As the peroxide breaks down it makes a small amount of heat inside the tooth, which the client never feels. That heat makes the pulp and dentin expand and pushes water out.
A dehydrated tooth looks whiter. It stays that way for roughly 72 hours, then takes water back from saliva and settles to its real colour.
After the first 15 minute session, some of what your client sees is dehydration and not bleaching. Nobody can tell how much. That is exactly why you always do at least two sessions, and why the treatment is three.
On the exam. This lesson answers question 14.