Abstract: A system for determining dental erosion by measuring the translucency of a tooth at the same location of the tooth at least two points in time during the lifetime of a person or an animal, said system comprising a device provided with a carrier on which a light source and a light sensor are mounted, which carrier can be placed against a tooth or a molar, preferably against the cutting edge thereof, and which system further comprises electronic processing means, which are designed to convert the signal from the light sensor into a quantitative value, means which are designed to store a first determined value from the sensor, means which are designed to compare a second determined value from the sensor with the first determined value, and means which are designed to communicate a representative of the result of the comparison to a user.