Fluoride effect on the process of alveolar bone repair in rats: evaluation of activity of MMP-2 and 9

Resumo

The aim of this study was to evaluate comparatively the
effect of fluoride (F) on the activity of matrix metalloproteinases 2 and
9 (MMP-2 and MMP-9) involved in process of alveolar bone repair.
Material and methods: This study used 4 groups of Wistar rats with
80 days of life (n = 160) which received drinking water containing
different doses of fluoride (NaF): 5, 15, 50 ppm and deionized water
(control) throughout the experiment. These animals had their right
upper incisors extracted. After extraction, the animals were euthanized
at 7, 14, 21 and 30 days and the hemi-maxillae were collected for
microscopic analysis (Hematoxylin and Eosin and immunohistochemistry
for MMP-9) and zymography (MMP-2 and 9). Results: Microscopically
the process of bone repair was similar in all groups, being noted only
a delay of the blood clot resorption and bone formation in the group
of 50 ppm F. The expression for MMP-9 showed differences between groups only during the initial repair (7 days). However, the zymography
showed no significant differences between treated and control groups.
Conclusion: Ours results suggest an effect of fluoride on the activity
of MMPs 2 and 9 at the initial period of alveolar repair which could
be associated to the process of blood clot remission and delay in bone
repair. Further studies are needed to establish the relationship between
the initial process of resorption of the blood clot, and the involvement
of MMPs 2 and 9 and its regulators/tissue inhibitors.