Systematic studies are made on the CO2- signal in tooth enamel to improve the calculation of the absorbed dose D(E). They consist of experiments on the effect of heating on the CO2- signal and the examination of the long-term development of the signals after irradiation and after heating experiments. On suitable teeth both single- and multiple-aliquot methods were used to calculate an absorbed dose D(E). The peak to peak intensity of the CO2- signal shows an enhancement within 3 days of irradiation. Furthermore a transient increase in the signal intensity after heating tooth enamel at 120 degrees C is observed, which mostly fades within 10-20 days. After artificial irradiation it is necessary to wait at least 3 days before electron spin resonance (ESR) measurements can be done. Differences in signal growth curves obtained using various protocols, for example single- or multiple-aliquot methods with and without heating after irradiation, are presented. Results for tooth enamel are compared with analogous experiments on the CO2- signal in carbonates.