Evaluation of density of xcalcium hydroxide pastes in dogs mandibles
publicado na revista : BRAZILIAN ENDODONTIC JOURAL 3(2):24-30, July/Dec.,
Key Words: Calcium hydroxide, intracanal dressing,
| INTRODUCTION | MATERIAL and METHODS
| RESULTS and DISCUSSION | CONCLUSION
hydroxide influences the enzymatic activity of bacteria which is reflected
in growth, cellular division and bacterial metabolism. The chemical and
biologic actions of calcium hydroxide on tissue and bacteria have made
this medication indispensable in Endodontics. The correct filling of thc
root canal is as important as the effectiveness of calcium hydroxide, because
the lack of direct contact of this dressing interferes with its mechanism
o faction. In order to better visualize the filling of the pulpal cavity,
radiopaque substances, such as zinc oxide, iodoform and barium sulfate
have been added to calcium hydroxide. However when the root canal is well
filled, dentin and calcium hydroxide paste in association with saline solution
clinically present themselves with the same radiopacity, causing the disappearance
of root canal light. The aim of this work is to study the density of calcium
hydroxide pastes with different vehicles, with no association with radiopaque
substances and in comparison with dentin density. Considering the results
of this work, it can be observed that it is not necessary to add radiopaque
substances to calcium hydroxide pastes, because pastes used without them
showed densities similar to dentin. In addition, when any substance is
added to calcium hydroxide, even an inert one, it represents one more factor
influencing biological processes and possibly of diminishing the amount
of hydroxyl and calcium ions available, which represents one of the reasons
for its use.
dressing continues to be the target of discussions. Considerations about
thc real necessity of its use in pulpal necrosis and apical periodontitis,
the selection of thc substance to bc used, the time it should remain in
the root canal, its effect on different microorganisms found in endodontic
infection and its influence on tissue healing are justifications for new
research structured within adequate critical analysis and well established
the amount of research carried out, calcium hydroxide has withstood criticism
and experimentation and has proven to be the best therapeutic option as
na intracanal dressing. The principle action of calcium hydroxide involves
the ionic dissociation into hydroxyl ions and calcium ions and its influence
on tissue healing and microbial control ( 6-13). ESTRELA and PESCE (12)
chemically analyzed the release of hydroxyl ions and calcium ions from
calcium hydroxide pastes in connective tissue of dogs and demonstrated
that when calcium hydroxide is placed within the root canal, 45.89% and
54.11% were dissociated into hydroxyl ions and calcium ions, respectively.
HOLLAND (15) analyzed histochemically the biological process of tissue
healing using calcium hydroxide, and reported the formation of five zones,
clotting superficial necrosis zone, superficial grainy zone, deep grainy
zone, proliferation zone and connective tissue zone. He also reported the
importance of calcium ions in the mineralization process. The influence
of calcium hydroxide on microorganisms was studied by ESTRELA et al. (13)
who analyzed the action of hydroxyl ions on microbial enzymes in the cytoplasmic
membrane, causing changes in the transport of nutrients and in the structure
of organic components. This interference in biosynthetic processes that
are essential to the life of microorganisms can also be analyzed through
the process of lipid peroxidation and influenced by hydroxyl ions. Thus,
the quantity of hydroxyl ions existing can lead to the enzymatic deactivation
studies have recommended the addition of other substances to calcium hydroxide,
with the aim of improving some of its properties. Among these substances
are vehicles that can speed up or slow down ionic dissociation, substances
that aid the filling of the pulpal cavity by means of their consistency,
substances that are used as antimicrobial medium and medium that enhance
correct filling of the canal is as important as the effectiveness of calcium
hydroxide because since the lack of direct contact of this dressing interferes
with its mechanism of action (6-7). . In order to better visualize the
filling of the pulpal cavity, radiopaque substances, such as zinc oxide,
iodoform and barium sulfate have been added to calcium hydroxide. However,
when thc root canal is well filled, dentin and calcium hydroxide paste
in association with saline solution clinically present themselves with
the same radiopacity, causing the disappearance of root canal light.
these factors, the aim of this work is to study the density of calcium
hydroxide pastes with different vehicles, with no association with radiopaque
substances and in comparison with dentin density.
study was carried out on root canals (2nd and 3rd mandibular premolars)
of dogs’ mandibles, divided into blocks. Samples were kept in saline solution
for 7 days. Teeth were prepared until ISO #50 K-file (Maillefer, Switzerland),
1 mm short of the apical foramen, using the cervical preparation technique.
The cervical third was enlarged with #2 Gates-Glidden burs. Three ml of
1% sodium hypochlorite was used for irrigation after each file, during
instrumentation of the root canals. Root canals were then dried and filled
and placed in 17% EDTA (pH 7.2) for 3 mim, and then dried again.
root canals were filled with a mixture of calcium hydroxide paste (Pró-analise,
Quimis, Mallinkrodt Inc., USA) and one of the 3 vehicles: saline, propylene
glycol 400 and camphoraled paramonoclorophenol (CPMC), with the consistency
of tooth paste. Root canals were filled with the aid of the last file used
in canal preparation. Simultaneously to the movement of penetration/removal
and anti-clockwise rotation of file, pastes were condensed and compressed
by means of a file and absorbent paper points, until the complete filling
of cervical third could be observed
placement of the calcium hydroxide paste, the teeth were radiographed together
with an aluminum stepwedge (Alcan Alumínio do Brazil S.A., Porto
Alegre, RS, Brazil) in order to evaluate the densities of teeth and dentin.
After obtaining radiographs showing the image of the aluminum step-wedge,
canals of each group were emptied using # 10 file K-file (Maillefer) and
flushed with saline solution and radiographed again to confirm if they
had been completely emptied, having in mind their reuse for the application
of the two other pastes. After root canals had been filled with thc other
pastes, teeth were radiographed again in order to verify if they had been
of density of calcium hydroxide pastes was performed using an aluminum
step-wedge manufactured according to SCARPARO et al. . The chemical composition
of the aluminum alloy was as follows: 6063 alloy; Al-base; Si- 0.60%; Fe-0.35%;
Au- 0.10%; Mn 0.10%; Mg- 0.90%; Ar- 0.10%; Zn- 0.10%; Ti-0.10%; Others
- 0.15%. This alloy was used to manufacture a 7- step wedge ranging from
4.0 to 10.0 mm in height; 3 cm in length and 3 mm in width. Its dimensions
were adjusted to the size of film and to the contrast produced between
steps of radiographic image. Thus, each radiograph showed the image of
the aluminum stepwedge in the region of the tooth in which the optical
density could be compared.
periapical radiographs (Kodak, UltraSpeed, USA) were taken of each tooth,
(2 nd . showing the root canal filled and densitometer and (3rd)
final after complete emptying. All radiographs were taken using the same
machine (Dabi-Atlante, Spectro II, 70KV, 10 mA, Ribeirão Preto,
SP, Brazil), with a 4-em focus-film distance and 0,5-s exposition.
Radiographic processing was performed at once for the three groups, through
time temperature method. An acrylic support was used while the radiographs
were taken, always holding the same position. All radiographs showed quality
image, sharpness and contrast appropriate for analysis.
were established between the steps that ranged from l to 7, for dentin
and for calcium hydroxide pastes, in order to assess density. With this
objective, 3 appraisers individually observed each radiograph using a negative
viewer located in an appropriated room and determined comparatively dentin
density with calcium hydroxide pastes, in each root. The final parameter
of assessment was quantified by the step (l to 7- density values were expressed
in aluminum-equivalent rnm/A1/Eq.) corresponding to paste and to dentin
density. A comparative and statistical analysis can be established by means
of the average of the values corresponding to the wedge’s steps. The three
thirds of root were analysed together. Figure
1 shows the aluminum step-wedge that was manufactured for this study; Figures 2
3, 4 to 5
show teeth after root canal preparation and after placement and complete
filling of the canal with calcium hydroxide pastes, in which densities
of dentin can be compared with densities of pastes used in the process.
parameters for the use of intracanal dressing can be established from the
better understanding of the mechanism of action of calcium hydroxide on
tissues and microorganisms. The comparison of densities between different
groups of calcium hydroxide pastes and between each group of calcium hydroxide
pastes and dentin was performed in pairs using the Wilcoxon non-parametric
test for paired observations, at a significance level of 5%. In terms of
coincidence. there was no significant difference between thc three assessments
performed by different appraisers. The comparison of the variation between
appraisers revealed a coincidence of 89% in the assessment performed, and
the Kappa values ranged from 0.60 100.65 for each pair of appraisers. The
results of this study did not show statistically significant differences
when the densities of calcium hydroxide pastes were compared between them
nor when they were compared with dentin densities, as expressed in Table
1 and can be visualized in Figures 2 to 5.
radiographic images provide important information. Different studies suggest
methods of image analysis (1-5,14,19,20). . However, it is difficult to
analyze a three-dimensional aspect presented in just one plane. CARVALHO
(4) interpreting radiographs of bone lesions that were experimentally produced
in dry human mandibles, reported that the deformities restricted to the
cancellous bone were only observed in larger proportions. Images became
clear when, by means of enlargement of deformities, jointed trabeculae
and the inner surface of the lingual and/or buccal cortex were destroyed.
methodology of this study using an aluminum step-wedge for density analysis
has been used by others. SCARPARO et al.(20) developed au exploratory methodology
to analyze bone density in the mandible, using an aluminum step-wedge as
a numerical referential. PUPIN et al.(19) evaluating bone density through
optical reading of the molar region in dry mandibles, observed that there
were no statistically significant differences between bone density values
of the right and left sides.
the context of this research, it is important to emphasize that the correct
preparation of root canal is essential to thc cleansing process, also helping
the filling with calcium hydroxide paste. Compression of paste relies on
its appropriated consistency aided by the use of a suitable filling technique.
the results of this study, it can be observed that it is not necessary
to add radiopaque substances to calcium hydroxide pastes, because pastes
used without them showed densities similar to dentin. In addition, when
any substance is added to calcium hydroxide, even an inert one, it represents
one more factor influencing biological processes and possibly of diminishing
the amount of hydroxyl and calcium ions available, which represents one
of the reasons for its use.
that the biological effects of calcium hydroxide lead to the activation
of alkaline phosphatase, which, in turn, positively influences the mineralization
process and favor the deactivation of bacterial enzymes aiding the antimicrobial
effect, the importance of thc speed with which hydroxyl ions are released
together with their availability in the environment in which their effectiveness
is desired can be deduced.
factor to he analyzed is the possibility that calcium hydroxide is reabsorbed
in the canal, with only the radiopaque substance remaining and giving the
false idea that it keeps on acting. This factor should bc considered carefully,
because has been no advantage of adding other substance to calcium hydroxide
has been noted (6-13).
(6) analyzed the antimicrobial effectiveness of calcium hydroxide diffused
by different substances. Microorganism tested were Streptococcus mutans,
Streptococus faecalis, Staphylococcus aureus. Pseudomonas aeruginosa, Bacillus
subtillis Candida albicans and a mixture of these microbial samples. Among
the vehicles tested were: saline solution, CPMC, chlorhexidine. Fiagyl®
(Metronidazole), Otosporim® and sodium lauryl sulfate. During the comparison
of the results obtained in the experimental periods of exposition — 1 minute,
48 and 72 hours, and 7 days-the absence of antimicrobial synergy between
calcium hydroxide and tested vehicles called the attention and supported
the recommendation for the use of an inert and periapical-tissue-non-aggressive
vehicle, such as saline solution and distilled water. These vehicles influence
antimicrobial activity as they speed up ionic dissociation and diffusion
and at the same time facilitate hydroxyl ions transportation and activity
and activity in dentinal mass. Thus, the vehicle acts like an assistant
in this process, giving calcium hydroxide chemical characteristics (dissociation,
dissociation, diffusibility and filling) that are decisive to the antimicrobial
potential and tissue healing capacity.
this study, watery hydrosoluble (saline solution), viscous hydrosoluble
(propylene glycol 400) and oily (CPMC) vehicles were compared, and it could
be observed that the consistency of paste and filling technique were important
factors, since there were no differences among their densities nor when
their densities were compared to dentin densities, although research identifies
advantages in the use of pastes with hydrosoluble vehicle, such as saline
1. Densities of pastes and dentin by steps (values expressed in aluminum/equivalent/mm)
on the results of this study, the following conclusions are made:
There were no statistically significant differences between optical reading
values of densities of pastes analyzed or when they were compared to dentin
Addition of radiopaque substances to calcium hydroxide is not necessary,
because calcium hydroxide paste density is similar to dentin density, provided
that the root canal had been properly filled.
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