Whitening destroys teeth
Scientists have proved that enamel whitening damages the "living" part of the teeth
Teeth whitening is dangerous for their health for the reason that hydrogen peroxide not only cleanses the enamel, but also penetrates into the deep tissues of the teeth and damages protein molecules. This conclusion was reached by biologists who told about the results of their experiments at the Experimental Biology 2019 conference in Orlando, USA.
"Our experiments show that the amounts of hydrogen peroxide present in the whitening strips are quite enough to penetrate deep into the tooth and completely destroy the collagen present inside the dentin. It is not yet clear whether this protein can be restored and how permanent these damages are," she said Kelly Keenan from Stockton University in Galoway (USA).
The teeth of humans and other mammals consist of "dead" enamel and several "living" parts – dentin, pulp and nervous tissue. Enamel, in turn, consists of two main elements – strong and extremely resistant to the action of various irritants of hydroxyapatite threads, as well as the "glue" that binds them in the form of a mixture of various amorphous minerals.
This "cement" gradually corrodes if carious microbes that secrete acids appear on the surface of the teeth, or if the enamel is mechanically damaged. In the resulting microcracks, new colonies of bacteria settle, whose appearance accelerates the process of tooth destruction and leads to the formation of a carious cavity.
In the past, scientists believed that the treatment of teeth with hydrogen peroxide slightly damages the enamel and does not penetrate into the "living" part of the tooth, but at the same time removes tartar and other "debris" from their surface. With appropriate care, as dentists assumed, further development of problems could be avoided.
Keenan and her colleagues checked whether this is really the case by following how hydrogen peroxide affects not only the enamel, but the entire tooth as a whole. To do this, scientists purchased several recently removed teeth from dentists and placed them in an artificial analogue of saliva, where they were "cooked" for several days.
In part of the samples, biologists added the same amount of hydrogen peroxide that is present on the surface of cleaning strips that are used today by American dentists for teeth whitening. Every few hours, Keenan and her colleagues separated small samples of dental tissue from these samples and monitored all changes in their condition.
These measurements unexpectedly showed that the amount of protein in the inner layers of the teeth was rapidly decreasing. This forced scientists to study in detail how dentin interacts with hydrogen peroxide, experimenting on pure samples of this tissue in test tubes.
It turned out that this substance not only decomposes proteins by itself, but also makes collagen, the basis of "living" dental tissue, much more vulnerable to the action of various enzymes that destroy unnecessary proteins inside the body. At the same time, peroxide begins to decompose proteins in the first ten minutes after tooth treatment.
This, according to the researchers, may explain why many people complain about the increase in dental problems after they have decided to improve their appearance. Therefore, they advise avoiding such procedures until it becomes clear whether collagen is being restored and what consequences its disappearance entails.
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