Journal article

Publication year: 2000

Pages: 12-24

Journal: Anatomical Record

Volume number: 259

Issue number: 1

Publisher: Wiley

Abstract: 

The pathological alterations of enamel structure in the teeth of wild
boars from fluoride polluted areas in N‐Bohemia (Czech Republic) and
S‐Saxony (Germany) were studied on a macroscopic and a microscopic
level. Mandibular bone fluoride concentration (mg F⁻/kg, dry
wt; mean ± SD, individuals <24 months of age) in the specimens from
N‐Bohemia (754.3 ± 149.6) and S‐Saxony (490.8 ± 135.1) was significantly
higher than that of controls (free of dental fluorosis), originating
from the western part of Germany (304.7 ± 91.0). Fluoride content in
bulk enamel (mg F⁻/kg, ash wt) of fluorotic permanent teeth
from N‐Bohemia (382.1 ± 165.2) and S‐Saxony (125.0 ± 38.3) was likewise
significantly increased over that of non‐fluorotic control teeth from
W‐Germany (33.6 ± 26.7). Macroscopically, fluorosed wild boar enamel
exhibited opacity and discoloration of varying extent, accentuated
perikymata as well as hypoplastic and posteruptive surface defects.
Microradiographic and scanning electron microscopic analyses revealed
enamel subsurface hypomineralization, accentuated Retzius lines and
occurrence of broad, hypomineralized incremental bands of abnormal
structure underlying hypoplastic enamel surface defects. The presence of
zones of aprismatic enamel was associated with these bands. Incremental
bands with altered enamel structure and enamel surface hypoplasias,
both denoting a severe disturbance during the secretory stage of
amelogenesis, have previously been observed in rodents following acute
parenteral fluoride dosing. It is concluded that in the chronically
fluoride exposed wild boars periods of especially elevated plasma
fluoride levels exerted an acute toxic effect on the secretory
ameloblasts. A feature not previously reported from fluorosed enamel was
the occurrence of canal‐like structures that originated at the broad
incremental bands and extended into the external enamel. The presence of
these canals presumably results from a delay in the resumption of
secretory activity by groups of ameloblasts following a fluoride insult.
Based on experimental evidence in domestic pigs and in sheep, the
overall subsurface hypomineralization of fluorosed wild boar enamel is
attributed to a disturbance of enamel maturation. The distribution of
fluorotic enamel changes within the dentition of the wild boars could be
related to the developmental sequence of tooth formation in the
species. Teeth whose crown formation took place prenatally (deciduous
teeth) or largely pre‐weaning (permanent first molars) exhibited no or
only moderate fluorotic enamel alterations. Based on the extension of
enamel surface hypoplasias along the coronoapical axes of the tooth
crowns, the timing of excess fluoride exposure that caused a marked
disruption of enamel matrix secretion was estimated in specimens with a
known date of death. The results indicate that the wild boars had been
exposed to a particularly severe fluoride impact during autumn and
winter of their first year of life.