Abstract
Introduction
The aim of this study was to evaluate the effect of 10% ascorbic acid or 10% sodium
ascorbate on organic matrix collagen of bovine dentin root canal walls after irrigation
with 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA),
or 0.9% sodium chloride.
Methods
Eighty bovine incisors were randomly divided into 8 groups (n = 10): group 1, 0.9%
sodium chloride (control); group 2, 5.25% NaOCl + 17% EDTA (NaOCl + EDTA); group 3,
5.25% NaOCl + 17% EDTA + 10% ascorbic acid (NaOCl + EDTA + AA); group 4, 5.25% NaOCl
+ 17% EDTA + 10% sodium ascorbate (NaOCl + EDTA + SA); group 5, 5.25% NaOCl (NaOCl);
group 6, 17% EDTA; group 7, 10% ascorbic acid (AA); and group 8, 10% sodium ascorbate
(SA). Teeth were chemomechanically prepared, submitted to histologic processing, and
stained with Sirius Red dye to be analyzed under polarized light microscopy. Absorbance
assay was also performed to confirm the loss of collagen.
Results
NaOCl + EDTA and NaOCl groups presented a significantly different birefringence pattern
compared with the control group (P < .05). The measurement of the optical retardations of NaOCl + EDTA + SA indicated
that this group was not statistically different from the control group. Although the
measurement of the optical retardations of NaOCl + EDTA + AA was statistically different
from the control group, the results were significantly higher than for NaOCl + EDTA.
The birefringence of EDTA, AA, and SA groups was not statistically different from
that of control group. The absorbance assay of NaOCl + EDTA and NaOCl groups confirmed
the loss of collagen (P < .05).
Conclusions
It is possible to conclude that 5.25% NaOCl, whether associated or not with 17% EDTA,
causes birefringence alterations and loss of dentin collagen. These alterations reduced
the ability of Sirius Red to bind with collagen fiber molecules. The reductions in
the optical retardation values could be reversed by the application of either 10%
ascorbic acid or 10% sodium ascorbate after 5.25% sodium hypochlorite and 17% EDTA
irrigation.
Key Words
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Article info
Publication history
Published online: August 08, 2011
Footnotes
Supported by grants of CNPq (141281/2007-3).
Identification
Copyright
© 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
