[en] The aim of this paper is to investigate some sources of uncertainty in the EPR dosimetric signal amplitude of irradiated tooth enamel. The paper evaluates the uncertainty induced by steps of sample preparation and by the use of a reference sample that are nowadays considered consolidated and that might have been overlooked. The investigated influence quantities are the grain size of the tooth enamel powder sample, sample moisture, the disinfection methods and the range of variability of the reference sample EPR amplitude. It is shown that some of these features need further investigation