Sixtyfreshly extracted human premolarteeth with straight single root canal wereselected and stored in distal water. To maintain standard root length of 12 mmtheteeth were decoronated and randomly divided into 5 groups (n = 12). Measurements of the working lengthwere done by deducting 1mm from recorded root length with #10 K-files(DentsplyMaillefer, Tulsa). Conventionalirrigation protocol was followed for three groups.
After using each file andbefore 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 of5.25% NaOCl.
Group C (Smear OFF) –1 ml of Smear OFF (Vista dental,) for 1 minute followed by 3 ml of 5.25% NaOCl.Incontinuous soft chelating irrigation protocol was followed for 2 Groups D (ChloroquickLow) and Group E – Chloroquick High (innovationsendo). After use of each filecanal was irrigated with 2 ml of respective Chloroquick solution.
Afterinstrumentation, 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 samesolution. Group E (Chloroquck High)– 1 ml of Chloroquick High solution (18%HEBP + 5.25%NaOCl) for 1 minute andfinal rinse with 3 ml of same solution. In-between two solution canals were rinsed with 5 mlof distilled water and solutions were introduced into the canals by means of a30-G side vented needle, which penetrated within 1 to 2 mm from the workinglength. In the end root canals were rinsed with 5ml of distilled water anddried with paper points.Finally, on the buccal and lingual surfaces of eachroot two longitudinal groves were prepared using diamond disc withoutpenetrating into the canal. The roots were then split into two halves with achisel.
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 AAet al. where scores were given as follow score 1 = no smear layer; no smearlayer was detected on the surface of the root canals and all tublues were openand clean; score 2 = moderate smear layer; no smear layer was observed on thesurface of thr root canal, but debris were present in tubules; score 3 = heavysmear layer; the smear layer covered the root canal surfaces and debris werepresent in tubules.All the images were scored by an endodontist who wasunaware of the groups and coding system to exclude observer bias.
Repeatedevaluation was done to ensure intraexaminer consistency. Data were analyzedwith the help of Kruskal-Wallis and Mann- Whitney U tests; p values werecomputed and compared with thr p = 0.05 level.