Changes in the paramagnetic centres in irradiated and heated dental enamel studied using electron paramagnetic resonance

The EPR signals in dental enamel produced by radiation and by heat were studied. The inherent background signal at g=2.005, and a radiation-produced signal at g=2.002 have different saturation behaviour with microwave power, and this affords a method of signal optimization. Heating enamel at temperatures from 100oC to 450oC produces a range of radical species from g=2.002 to g=2.005, which have been characterized by their g-values, line widths and saturation behaviour. Standard dental drilling produces a range of radicals which appear to be similar to those produced by heat. (author)