This coronal and middle third of the canals even

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 itsbiological,
antibacterial and tissue dissolving properties (13, 14), whereas the reduction
and removalof the inorganic matter is done with HEBP (11, 12).

Results of this present study showsremoval of smear
layer was more efficient in coronal and middle third as compared to apical
third. This finding is in agreement with results ofAbbott 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 layercomprehensively. (3,16).

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            Role
of surfactant has been discussed by many authors, in present study SmearClear,
SmearOFF and Chloroquick have surfactant in the solution. Abou-Rass and
Patonaiconfirmed 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
observationsof 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 thesignificantly 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 resultscan
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 withamalgamation 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 same time.

            Result
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.