Teeth are made of three layers: the outer enamel, an underlying dentin layer and a connective tissue that binds it to the gum.
Most studies on the safety of hydrogen peroxides have focused on enamel. The chemical is known to penetrate the enamel and reach the dentin, although in minimal amounts, explained Dr. Edmond Hewlett, associate dean at the UCLA School of Dentistry and spokesman for the American Dental Association, who was not involved in the new study.
Kelly Keenan, senior author of the study and associate professor of chemistry at Stockton University in New Jersey, said in a statement that she and her colleagues "sought to further characterize what hydrogen peroxides were doing to collagen."
Essentially, all whitening products in the United States contain hydrogen peroxide and / or carbamide peroxide, according to the American Dental Association.
"Our results show that treatment with hydrogen peroxide concentrations similar to those found in whitening strips is enough to make the original collagen protein disappear," Keenan said.
Hewlett cautions against the generalized results obtained in the extracted teeth, as they may not represent the same environment as a person's mouth.
Because the research is in its early stages, it's unknown how much the dentin is damaged, what this would mean for patients and whether the damage is permanent, he said.
"The tooth-whitening products that the abstracts have been talking about have been around for decades and used by millions and millions of people," he said. "The most common side effect that dentists see after using whitening strips is the tooth sensitivity, which is transitory and does not represent the underlying damage to the tooth, he said.
Hewlett recommends looking for products that have the American Dental Association's seal of acceptance, which means they have been tested for safety and effectiveness by the organization.