The aim of this investigation was to find out if the fluoride emission from the thermal power plants of the Cottbus region causes clinically provable changes in the hard substance of the tooth and at the marginal periodontium. The epidemiological examination was carried out on 8496 children of 3-16 years born in that region and in a region without collective fluoridization measures preventing dental caries. The investigation covered, besides sequency, the intensity of the existence of enamel stain. To determine the frequency of caries, the df/-t-index was applied to deciduous teeth and the DMF/T-index to permanent teeth. The assessment of the marginal periodontium was done by using the criteria of morbidity, the number of the average affected PM-units and PM-index according to Muehlmann and Mazor. The results of the examinations show that the existing environmental pollution does not influence the frequency and intensity enamel stain. Furthermore it is found that the occurrence of caries of deciduous and permanent teeth in regions where the air is polluted by large power plants is less than in regions without pollution. This result was established but it is not always proven statistically.