This study gives the
understanding of the process of smear layer removing ability of conventional
irrigation protocol and continuous soft chelating irrigation protocol. The main
objective of instrumentation is to promote effective irrigation, disinfection,
and filling. Smear layer production is seen while instrumentation procedures of
root canal which has to be eliminated with the use of irrigating solution. All
the functions required from an irrigant to remove smear layer from root canal
wall cannot be achieved by any single irrigating solution. Therefore, combined
use of 2 or several irrigating solutions is required for optimal removal of
smear layer (5). Whereas Chloroquick solution having HEBP as a soft chelating
agent and can be combined with NaOCl to become single solution for disinfecting
root canals. Highlight of such combination of NaOCl and HEBP is that the NaOCl
doesn’t loses its biological, antibacterial and tissue dissolving properties
(13, 14), whereas the reduction and removal of the inorganic matter is done
with HEBP (11, 12).
Results of this present study
shows removal of smear layer was more efficient in coronal and middle third as
compared to apical third. This finding is in agreement with results of Abbott PV, Heijkoop PS et al.
study and many studies which have
proved in past that an effective cleaning action in the coronal and middle
third of the canals even with different irrigation solution, time, and volume
(15, 16). In coronal and middle third areas where a larger canal diameter allows
better flow of solution and more time to be in contact with dentine wall which allows
the solution to remove smear layer comprehensively. (3,16).
of surfactant has been discussed by many authors, in present study SmearClear,
SmearOFF and Chloroquick have surfactant in the solution. Abou-Rass and Patonai
confirmed that reduction of surface tension of endodontic solutions improved
their flow into narrow root canals (17). Therefore, an addition of surfactants
to irrigation solution should improve its penetration into apical narrow part
of root canal. In present study, SmearClear and SmearOFF despite having additional
surfactant doesn’t show the significant removal of smear layer in apical third
when compared to control group of 17% EDTA, which does not have any addition
surfactant. This result is in accordance with the observations of Lui et al.
(18) and also, other studies have shown that calcium chelating ability of
solution is not improved by reducing the surface tension of the solution.
Present study results disply that the continuous soft chelating irrigation shows the significantly
better removal of smear layer than conventional irrigation protocol at apical
third level when 18% HEBP was used in combination with 5.25% NaOCl (Chloroquick
High). Where 9% HEBP in combination with 3% NaOCl (Chloroquick Low) did not
show any significance difference compared to conventional irrigation protocol
groups. These results can be attributed to chelating agent being more time in
canal and also chelating procedure is seen while instrumentation, unlike
conventional irrigation protocol where removal of smear layer is done only once
instrumentation is completed (19). Paque et al. demonstrated that the
accumulation of hard tissue debris in root canals when irrigated with amalgamation
of NaOCl and HEBP was significantly less
than irrigation was performed with 2.5% NaOCl alone (20). Another advantage of
this combination is that it has better tissue dissolution capacity by keeping
the hypochlorite- hypochlorous acid equilibrium towards hypochlorite (21). This
combination is affective on inorganic as well as organic part of smear layer at
of this study is in contrast to the recently published study by Aby
Kuruvilla et al. where 7% malic acid was
more effective in removing smear layer as compared to 17% EDTA and 18%
etidronic acid (22). This observation may be seen because 18% etidronic acid which
is soft chelating agent was merely used in a final rinse irrigation protocol.
There are very few studies available on use of
the continuous soft chelating agent for smear layer removal. In present study,
continuous soft chelating irrigation protocol shows promising results.
Within the limitation of this
in-vitro study both the protocols conventional as well as continuous soft
chelating irrigation protocols were able to remove smear layer at coronal and
middle third of the root canals but at apical third only continues soft
chelating irrigation protocol performed with Chloroquick High shows better
removal of smear.