Sixty teeth were decoronated and randomly divided

Sixty
freshly extracted human premolarteeth with straight single root canal were
selected and stored in distal water. To maintain standard root length of 12 mmthe
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:-

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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 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 at2000×magnificationscoronal (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 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 intraexaminer 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.