Various former studies have shown that the dentinal wall was
covered with smear layer after mechanical instrumentation of the root canals (1,2).
Regardless of the controversy over maintaining the smear layer it has been
demonstrated 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 successful debridement of the
root canals with mechanical procedures (3). There is no single solution is
efficient of removing both organic and inorganic parts of the smear layer. To
eliminate this smear layer combination of sodium hypochlorite (NaOCl) and
strong chelating agent such as Ethylenediaminetetraacetic acid (EDTA) is favored (8). It has been suggested
that smear layer was completely evacuated by 17% EDTA for 1min followed by 5.25%
NaOCl by Crumpton et al. (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 1minute
and 1ml of volume has been reported to be associated with dentinal erosion
SmearClear (Sybron Endo, Orange, CA) is a product recently
introduced for removing 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 yet can still reduce smear
layer Lottanti et al. 2009.
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.
Sixty freshly extracted human premolar teeth with straight
single root canal were selected and stored in distal water. To maintain
standard root length of 12 mm the teeth were decoronated and randomly divided
into 5 groups (n = 12). Measurements
of the working length were done by deducting 1mm from recorded root length with
#10 K-files (DentsplyMaillefer, Tulsa).
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
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 D (Chloroquick Low) 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 two solution canals
were rinsed with 5 ml of distilled water and solutions were introduced into the
canals by means of a 30-G side vented needle, which penetrated within 1 to 2 mm
from the working length. In the end root canals were rinsed with 5ml of
distilled water and dried with paper points.
Finally, on the buccal and
lingual surfaces of each root two longitudinal groves were prepared using
diamond disc without penetrating into the canal. The roots were then split into
two halves with a chisel. Then the specimens were mounted on the metallic
stubs, gold sputtered, and examined by a scanning electron microscope (FEI
Quanta 200 FE-SEM MK2, Netherlands). Images were taken at 2000× magnifications coronal
(9 mm to apex), middle (6 mm to apex), and apical (3 mm to apex) third of each
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 detected 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 thr root 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.
All the images were scored by
an endodontist who was unaware of the groups and coding system to exclude
observer bias. Repeated evaluation was done to ensure intra examiner
consistency. Data were analyzed with the help of Kruskal-Wallis and Mann-
Whitney U tests; p values were computed and compared with thr p = 0.05 level.
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
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.