Abstract
Introduction
The aim of this study was to characterize the formation and progression of experimentally
induced periapical lesions in TLR2 knockout (TLR2 KO) mice.
Methods
Periapical lesions were induced in molars of 28 wild type (WT) and 27 TLR2 KO mice.
After 7, 21, and 42 days, the animals were euthanized, and the mandibles were subjected
to histotechnical processing. Hematoxylin-eosin–stained sections were examined under
conventional light microscopy for the description of pulpal, apical, and periapical
features and under fluorescence microscopy for the determination of the periapical
lesion size. The subsequent sections were evaluated by tartrate resistant acid phosphatase
histoenzymology (osteoclasts), Brown and Brenn staining (bacteria), and immunohistochemistry
(RANK, RANKL, and OPG). Data were analyzed by the Mann-Whitney U and Kruskal-Wallis tests (α = 0.05).
Results
The WT group showed significant differences (P < .05) in the periapical lesion size and the osteoclast number between 7 and 42 days
and between 21 and 42 days. In the TLR2 KO group, significant differences (P < .05) in the periapical lesion size and the osteoclast number were found between
7 days and the other periods. There was a significant difference (P < .05) between the 2 types of animal regarding the periapical lesion size, which
was larger in the TLR2 KO animals. No significant differences (P > .05) were found between WT and TLR2 KO mice related to the pulpal, apical, and
periapical features; bacteria localization; and immunohistochemical results (except
for RANK expression).
Conclusions
TLR2 KO animals developed larger periapical lesions with a greater number of osteoclasts,
indicating the important role of this receptor in the host's immune and inflammatory
response to root canal and periradicular infection.
Key Words
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Article info
Publication history
Published online: April 30, 2012
Footnotes
This study is part of the master's dissertation of the second author (P.D.F.F.), who received a scholarship from the Brazilian Ministry of Health's Federal Agency for Support and Evaluation of Graduate Education (CAPES).
Identification
Copyright
© 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
