Sixtyfreshly extracted human premolar teeth with straight single root canal were preferredand stored in distal water.
standard root length of 12 mm were maintained by decoronatingthe teeth and then divided into 5 groups (n = 12) randomly. Working length was measured with #10 K-files and deduction of 1mmwas done from recorded root length. 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. GroupD- Chloroquick Low (innovationsendo) 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 solutions, 5 ml of distilled water was usedfor rinsing canal walls and solutions were introduced with the help of a 30-Gside vented needle (innovationsendo), which penetrated within 1 to 2 mm fromthe working length. In the end 5ml of distilled water were used to rinse rootcanal walls which were dried with paper points.
In the end of entire procedure, two longitudinalgroves were prepared with the help of diamond disc without cutting into thecanal. Grooves were prepared on the buccal and lingual surfaces of each root. Chiselwas used for splitting the teeth. Then the specimens were mounted on themetallic stubs and examined by a scanning electron microscope (FEI Quanta 200FE-SEM MK2, Netherlands). Images were taken at2000×magnifications coronal (9 mmto apex), middle (6 mm to apex), and apical (3 mm to apex) third of eachspecimen. Scoring criteria given by Torabinejad M, Khademi AAet al. where scores were given as follow score 1 = no smear layer; no smearlayer was observed 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 the canal, but debris were present in tubules; score 3 = heavy smearlayer; the smear layer covered the root canal surfaces and debris were presentin tubules.An endodntist who was unaware of groups and coding evaluatedand scored all the images to exclude observer bias.
Repeated evaluation wasdone to ensure intra-examiner consistency.