H. Kierdorf et U. Kierdorf, DISTURBANCES OF THE SECRETORY STAGE OF AMELOGENESIS IN FLUOROSED DEERTEETH - A SCANNING ELECTRON-MICROSCOPIC STUDY, Cell and tissue research, 289(1), 1997, pp. 125-135
Structural changes resulting from fluoride-induced disturbances of the
secretory stage of amelogenesis were studied in fluorosed dental enam
el of ten permanent premolars and molars from roe deer (Cervus capreol
us) and red deer (Cervus elaphus). The fluorosed enamel exhibited surf
ace hypoplasias of different depths and extents and an associated loss
of its normal prism/interprism structure. The occurrence of such apri
smatic enamel either was restricted to grossly accentuated and hypomin
eralized incremental (calciotraumatic) bands or affected more extended
areas to the bottom of the hypoplastic lesions. The fluoride-induced
disturbance of the secretory functions of the cells had thus been eith
er temporary or permanent. Layers of aprismatic enamel were regarded a
s denoting periods of reduced enamel matrix formation by secretory ame
loblasts lacking the distal, i.e., the prism-forming, portions of thei
r Tomes processes. Our observations also indicated that the transition
from the presecretory to the secretory stage of amelogenesis could be
affected by fluoride, thereby preventing the ameloblasts from achievi
ng their normal secretory function and from establishing fully formed
Tomes processes. Aprismatic enamel was formed throughout the secretory
stage of amelogenesis at these locations. The most severe ameloblast
reaction that could be deduced from our findings was an abrupt cessati
on of enamel matrix secretion. Some of the pathological changes observ
ed in fluorosed deer enamel showed striking similarities to those repo
rted in rodents after acute parenteral fluoride dosing. Thus, periods
of especially elevated plasma-fluoride levels in chronically fluoride-
stressed deer can cause a disruption in the function of secretory amel
oblasts similar to that following acute fluoride dosing in rodents.