Three new studies have shown that hydrogen peroxide, which is commonly found in teeth whitening products, can damage dentin within tooth enamel. Shockingly, many over-the-counter whitening strips contain 330x the recommended amount of hydrogen peroxide.
The study results were presented at the American Society for Biochemistry and Molecular Biology annual meeting during the 2019 Experimental Biology meeting that was held between April 6th and 9th in Orlando.
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Kelly Keenan, associate professor of chemistry at Stockton University in New Jersey, was one of the researchers. Her lab was used by undergraduates who conducted the three studies:
Keenan and team explain that there are three layers of the tooth. The outer layer is the enamel beneath which is the protein rich layer of the dentin. Underneath the dentin lies the connective tissue that binds the tooth with the gum.
Till date, studies have only looked at the effect of these whitening products on enamel. Keenan’s studies examine their effects on dentin rather than the enamel. Damage to the dentin can lead to teeth sensitivity and pain on eating hot or cold foods.
The studies reveal that the hydrogen peroxide present in these products can penetrate enamel and dentin. They found that the collagen in the dentin decreased with repeated use of these whitening products. Keenan said in a statement, “We used entire teeth for the studies and focused on the impact hydrogen peroxide has on the proteins.”
The team found that the major proteins present in dentin was broken down into smaller bits when they were treated with hydrogen peroxide. The collagen of the teeth also responded adversely to the hydrogen peroxide.
The team then used gel electrophoresis to analyse the protein in detail:
Our results showed that treatment with hydrogen peroxide concentrations similar to those found in whitening strips is enough to make the original collagen protein disappear, which is presumably due to the formation of many smaller fragments.”
The first study concludes that the “active ingredient in whitening treatments can penetrate the enamel, it can damage the non-collagen proteins in the teeth.”
The second and third studies also concluded that despite the small amounts of hydrogen peroxide used in whitening strips can damage the proteins found within teeth by hydrolysis.
The third study shows that hydrogen peroxide is capable of penetrating dentin. According to regulations, the whitening products should contain 0.1 percent or less amount of hydrogen peroxide. However, some products can comprise up to 33 percent hydrogen peroxide, warns the British Dental Association.
The researchers further warn that this loss of the protein did not appear to be reversible. This could mean that the damage could be permanent.
The authors acknowledged that the study was funded by Research and Professional Development Grant from Stockton University.