7.07.2020

How Peroxide Speeds up Remineralization and Cement Forming

Again thanks to Johan Nygren for doing most of the work to figure out the mechanism of how Peroxide can speed up remineralization.  He sent me this picture (click on it to go to the source)

https://books.google.cz/books?id=vnDSfpK_-EsC&pg=PA134&lpg=PA134&dq=hydroxyapatite+formation+hydrogen+ion&source=bl&ots=uTe-SoJ4Gz&sig=ACfU3U3U4fIBk3eHGAORh3z1FlVJk930Ww&hl=sv&sa=X&ved=2ahUKEwj2y8PdwbPqAhVS66QKHc2RBCoQ6AEwBHoECAgQAQ#v=onepage&q=hydroxyapatite%20formation%20hydrogen%20ion&f=false


 Basically the limiting factor to remineralization is the removal of H+ ions.  This typically isn't a big problem since hydroxyapatite powder has an OH- molecule which can react with the H+ released forming water, however this is not a free floating OH and is bound to the hydroxyapatite molecule.  Since it is bound it is less apt to react with H+ ions, especially when Ca ions are blocking it, see below picture.

So how would peroxide or hydrogen peroxide help this process?  Peroxide reacts with an OH molecule to produce electrons. These free electrons can quickly and easily react with H+ ions forming H2 gas.  While simple OH- of the hydroxyapatite will absorb the H+ ions released during remineralization, it is slower as the H+ ions will have to diffuse all the way to the backside of the hydroxyapatite molecule (nano or micro particles) to be absorbed.  If instead H2O2 is already reacting with the OH molecules "shooting" electrons wherever they are needed, the process of remineralization can be faster.

In basic medium:

Let me try to explain better.  H+ ions are released when a particle of hydroxyapatite bonds to a enamel surface.  Now these H+ ions can interfere with the attachment because their generation immediately cause the linkage between the hydroxyapatite and the enamel to break.  In order to push remineralization forward, we need to get rid of these H+ ions.  The H+ ions would typically have to travel all the way to a part on the hydroxyapatite molecule that is not bonding with the enamel to be absorbed to it's OH- without interfering with the attachment.  If instead of waiting for this diffusion of H+ ions to happen, we could instead use hydrogen peroxide to preemptively react with the OH- and create free electrons that can travel right to where they are needed and convert the H+ ions released instantly into H2 gas, thus speeding up the remineralization process.

When it comes to hydroxyapatite in dentifrices like teeth powder and toothpaste and mouthwash, time is critical since you only have a couple minutes for remineralization to happen.  Thus nHApP or Nano Hydroxyapatite Peroxide would be an ideal ingredient for these uses.  Also hydrogen peroxide or other peroxides such as magnesium peroxide or sodium percarbonate can work as well to support the remineralization of hydroxyapatite.


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