Patent ID: 8206689

Claim:
A method for forming a light scattering layer inside enamel of teeth, the method comprising: applying an oral preparation to teeth in which an endogenous colored substance is deposited in the depth of the enamel, wherein said oral preparation comprises: (A) from 0.02 to 0.2 wt. %, in terms of fluorine atom, of a fluoride ion supplying component which is at least one selected from the group consisting of sodium fluoride, sodium monofluorophosphate, lithium fluoride, ammonium fluoride, and a mixture thereof; (B) from 0.03 to 0.3 mol/kg of a combination of at least one organic acid selected from the group consisting of malic acid, tartaric acid, and a mixture thereof with a salt of the organic acid; (C) from 0.03 to 0.5 mol/kg of potassium ion; and (D) water; and wherein said oral preparation has a pH ranging from 3 to 5.5 when diluted with water to 30 wt. %.