Comparison of the crown size of teeth in children from a high and an optimum fluoride area in South Africa

An odontometric analysis was undertaken of the teeth of 6-7 and 14-15-yr-old schoolchildren exposed throughout life to a naturally fluoridated drinking water supply (2.5 ppm) in Klipfontein and of equivalent children living in the adjacent area of Garies (1.06 ppm). Measurements were made of the mesio-distal diameter of permanent maxillary and mandibular central incisors, second premolars and first and second molars; in addition, bucco-lingual measurements of the molars were made. In comparing the dimensions of teeth in the high- and optimum-fluoride samples, a tendency towards smaller dimensions in the former group was observed, but statistically significant differences applied to only some of the measurements. This finding suggests a reducing influence on crown size of an increase in the level of fluoride in the drinking water. Coupled with previous findings that increased the fluoride level from low or zero to optimal results in a reduction in crown size, an inverse relationship between crown size and fluoride level in the drinking water appears possible, but has not been confirmed in this study.