FLUORIDE CONTENT OF THE ENAMEL AND DENTIN OF HUMAN PREMOLARS PRIOR TOAND FOLLOWING THE INTRODUCTION OF FLUORIDATION IN NEW-ZEALAND

The fluoride content of the enamel and dentine of premolars was used a s a determinant of the availability of ingested fluoride in New Zealan d prior to and following the introduction of water fluoridation 40 yea rs ago. Premolar teeth, which developed during the periods (PRE and PO ST respectively) under study, were selected from teeth extracted from 12 to 14-year-old children resident in different geographic areas in t he country. The fluoride content, determined by multiple proton microp robe analyses, of surface enamel, deep enamel, and dentine, were for P RE teeth 440, 65 and 115, respectively. For POST teeth the mean values were significantly (p<0.001) higher, by 69, 29 and 102% respectively. The relevance of the change in fluoride content was assessed by compa rison with published reports on the fluoride content of teeth develope d in communities exposed to low (<0.5 ppm), optimal (1-2 ppm) and high (>3 ppm) naturally occurring fluoride levels in drinking water. The P RE teeth had a fluoride content associated with a low fluoride exposur e and POST teeth with optimal fluoride exposure during tooth developme nt. It was concluded that fluoride availability in New Zealand teeth h ad increased over the past 30 years but this increase is compatible wi th exposure of the community to optimal rather than excessive levels o f ingested fluoride.