"My dentist uses a mauve-coloured light to set white fillings. Can these lights cause cataracts if they are used on the top front teeth near to the eyes?"
Dr Fred Kavalier answers your health question:
Traditional fillings for tooth decay were made of amalgam, which is a mixture of metals such as mercury and silver. More modern white fillings are known as composite fillings. They are made from a combination of a polymer and glass. The white material is a soft paste when it is put into a tooth. The dentist then shines a blue or ultraviolet light on the paste, which sets off a chemical reaction that turns it into a strong, solid substance. Cataracts are more likely to form in the eyes of people who have been exposed to strong sunlight (which contains ultraviolet light) over many years. The blue or ultraviolet light which the dentist uses to set white fillings is a narrow beam that is directed at the filling for a short period of time (less than a minute). The amount of ultraviolet light is small and the length of exposure is short. In the unlikely event that a small amount of light managed to shine on your eyes, the risks would be insignificant. Dentists, who are using these lights every day, are advised to protect their eyes from excessive exposure.