A polarized light and microradiographic study of enamel in human primary teeth from a high fluoride area

Abstract

The enamel structure of primary teeth from a high fluoride area (4–6 parts/10 6) was compared with that of primary teeth from a low fluoride area (< 0.2 parts/10 6). Macroscopically, varying degrees of enamel mottling, including pitting, were recorded in teeth from the high fluoride area. In polarized light, the enamel formed in a low fluoride area exhibited a microporous zone confined to the prenatal enamel. The slightly-affected fluorosed teeth showed a widening of this inner zone, often combined with a tendency to increased subsurface porosity particularly in the cervical portion of enamel. The subsurface zone became more pronounced, corresponding to increasing degrees of fluorotic mottling. In the cervical enamel, porosity involved the full width of the enamel whereas elsewhere it formed a distinct zone in the outer third or half of the enamel. Microradiographically. this zone appeared hypomineralized beneath a well-mineralized surface layer. Quantitation of the birefringence along traverses from the surface to the enamel-dentine junction disclosed that the optical behaviour of these enamel defects was similar to that described in permanent teeth.