Various root canals with instrument (1,2). Disregarding

Various
former studies have shown that the dentin wall was covered with smear layer
after mechanical shaping of the root canals with instrument (1,2). Disregarding
of the controversy over retaining the smear layer it has been recognized that the
smear layer itself may be infected and may protect the bacteria within the
dentinal tubules (3). Smear layer not only contains organic components but also
have inorganic component in the form of dentin chips etc (1). The penetration
of intracanal disinfectants (4) and sealers into dentinal tubules were
prevented by smear layer, which affects the final seal of the root canal
filling (5, 6, 7).

Irrigants
are paramount for complete debridement of the root canals with mechanical procedures
(3). There is no single potent solution is appropriate for removing both
organic and inorganic parts of the smear layer. To eliminate this smear layer mix
of sodium hypochlorite (NaOCl) and strong chelating agent such as EDTA (Ethylenediaminetetraacetic acid) is
recommended (8). Crumpton et al. proposed
that complete evacuation of smear layer can be achieved by 17% EDTA for 1min
followed by 5.25% NaOCl (9,12). Till now there is no single solution which can
disinfect the root canal system as well as remove the smear layer. On the other
hand the application of strong chelating agent like EDTA for more than minute
and 1ml of volume has been reported to be associated with dentinal erosion
(10,11).

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SmearClear
(Sybron Endo, Orange, CA) is a product introduced for eliminating the smear
layer. It contains 17% EDTA solution in conjunction with a cationic (Cetrimide)
and an anionic surfactant. SmearOFF (Vista Detal Products) is Proprietary EDTA
and Chlrohexidine mix. It is prepared with combination of wetting agents and
surface modifiers for best outcomes. These solutions are used only as final
rinse.

Etridonic acid which is soft chelating agent appears
to have a nominal effect on dentine walls and still cut down smear layer. Lottanti et al.
showed that Etridonic acid (HEBP) can be used in combination
with NaOCl without affecting its proteolytic or antimicrobial properties (13,14). In contrast to EDTA, Etridonic
acid is a weak decalcifying agent and hence cannot be used as a mere final
rinse there for it is suggested that HEBP to be mixed with NaOCl to be used as
more complete root canal irrigation solution.

 

Chloroquick
(innovationsendo, India) is a combination of NaOCl and HEBP. Chloroquick High
contains 18% HEBP and 5.25% NaOCl while Chloroquick Low contains 9% HEBP and 3%
NaOCl both be mixed with surfactant tween 80 for complete root canal irrigation
solution. There for this study aims to compare the efficacy of continuous soft
chelating irrigation protocol with Chloroquick solutions to conventional
irrigation protocol on smear layer removal in coronal, middle, and apical
thirds of the instrumented root canals.

 

 

Materials
and methods

Sixty
freshly extracted human premolar teeth with straight single root canal were preferred
and stored in distal water. Standard root length of 12 mm were preserved by
decoronating the teeth and then divided into 5 groups (n = 12) randomly. Working length was measured with #10
K-files and deduction of 1mm was done from recorded root length.

Conventional
irrigation protocol was followed for three groups. After using each file and
before proceeding to the next canals were irrigated with 2 ml of 5.25% NaOCl.
After instrumentation, all teeth underwent final irrigation as follows:-

Group A(control, EDTA) –
1ml of 17% EDTA for 1 minute followed by 3 ml of 5.25% NaOCl.

Group B (Smear Clear)–
1 ml of Smear clear (Sybron Endo, Orange, CA) for 1 minute followed by 3 ml of
5.25% NaOCl.

Group C (Smear OFF) –
1 ml of Smear OFF (Vista dental,) for 1 minute followed by 3 ml of 5.25% NaOCl.

In
continuous soft chelating irrigation protocol was followed for 2 Groups. Group
D- Chloroquick Low (innovationsendo) and Group E – Chloroquick High  (innovationsendo). After use of each file
canal was irrigated with 2 ml of respective Chloroquick solution. After
instrumentation, all teeth underwent final irrigation as follows:-

Group D (Chloroquick Low)
– 1 ml of Chloroquick Low solution (9%HEBP + 3%NaOCl)  for 1 minute and final rinse with 3 ml same
solution.

Group E (Chloroquck High)
– 1 ml of Chloroquick High solution (18%HEBP + 5.25%NaOCl) for 1 minute and
final rinse with 3 ml of same solution.

In-between solutions, 5 ml of distilled water was
used for rinsing canal walls and solutions were introduced with the help of a
30-G side vented needle (innovationsendo), which penetrated within 1 to 2 mm
from the working length. In the end 5ml of distilled water were used to rinse
root canal walls which were dried with paper points.

In the end of entire procedure, two longitudinal
groves were prepared with the help of diamond disc without cutting into the
canal. Grooves were prepared on the buccal and lingual surfaces of each root.
Chisel was used for splitting the teeth. Then the specimens were mounted on the
metallic stubs and examined by a scanning electron microscope (FEI Quanta 200
FE-SEM MK2, Netherlands). Images were taken at2000×magnifications coronal (9 mm
to apex), middle (6 mm to apex), and apical (3 mm to apex) third of each
specimen.

Scoring criteria given by Torabinejad M, Khademi AA
et al. where scores were given as follow score 1 = no smear layer; no smear
layer was observed on the surface of the root canals and all tublues were open
and clean; score 2 = moderate smear layer; no smear layer was observed on the
surface of the canal, but debris were present in tubules; score 3 = heavy smear
layer; the smear layer covered the root canal surfaces and debris were present
in tubules.

An endodntist who was unaware of groups and coding
evaluated and scored all the images to exclude observer bias. Repeated
evaluation was done to ensure intra-examiner consistency.

 

 

 

RESULTS

Descriptive
statistics were expressed as numbers for each group. The efficacy of various
agents for smear layer removal was assessed by comparison of groups using
Kruskal Wallis ANOVA and Mann- Whitney U test. In the above tests, p value less
than or equal to 0.05 (p?0.05) was taken to be statistically significant. All
analyses were performed using SPSS software version 17.

The results for smear
layer scores in each group at coronal, middle and apical are presented in Table
no 1, 2 and 3. The examination of the surface of root canal walls at coronal
third groups showed less or no smear layer (Fig. 1) and there was no statistically significant
difference (p_0.643)Most
samples at middle thirds shows no smear layer or minimal smear layer present
(Fig. 2) and there was no
statistically significant difference at middle layer of root canals (p_0.615). Chloroquick High group showed better smear layer removal at the apical thirds(Fig.
3). Chloroquick High shows statistically significantly better
(p_0.029) as compared to the other groups. Mann-Whitney U test shows that
Chloroquick High is able to remove better smear layer compared to Chloroquick Low
(p_0.028). Choloroquick Low has similar chelating
ability as compared to other solution there is no statically significant
difference at apical third. 

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