Teeth-whitening products used to maintain a dazzling smile may cause hidden tooth damage, research suggests.
Studies have found that the active ingredient in over-the-counter whitening strips, hydrogen peroxide, fragments dentin protein.
Dentin lies beneath the tooth's enamel outer layer and provides it with support.
It is sandwiched between the enamel and connective tissue that binds tooth roots to the gums.
Most studies of whitening strips have focused on the tooth enamel, but the new research looked at what happened to dentin in teeth exposed to hydrogen peroxide.
The American team found that collagen protein in the dentin was broken up and appeared to vanish from laboratory images.
Dr Kelly Kennan, from Stockton University in New Jersey, said: "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 study, presented at the 2019 Experimental Biology meeting in Orlando, Florida, did not seek to find out whether the damage was permanent, the scientists pointed out.
Next they plan to further characterise the fragments and investigate whether hydrogen peroxide has the same effect on other tooth proteins.
