To evaluate the effects of presence and absence of smear layer with different instruments and obturation methods on microleakage of root canal-filled teeth.

A total of 100 extracted human maxillary central incisors with closed apices and single roots were taken for the study. The teeth were divided into six groups A to F consisting of 15 teeth each. Control group consisted of 10 teeth with five positive and five negative teeth each.

Groups A, B, C and D were instrumented with rotary files and groups E and F were instumented with conventional stainless steel files.

Groups A, B, C and D were flushed with 3 ml of EDTA to remove the smear layer prior to obturation. All teeth were flushed with 5% NaOCl, then obturated with AH-26 sealer with lateral condensation technique on groups C, D, E, F and injectable thermoplasticized gutta-percha obturation technique on groups A and B.

Using electrochemical technique the current flow in the circuit was observed for 45 days. The magnitude of the current for each tooth was directly proportional to the extent of leakage. At the intervals of 10, 20, 30 and 45 days the groups A-F were compared to identify statistically significant differences using students t-test.

Significantly less microleakage occurred when the smear layer was removed and when the canals were obturated with thermoplasticized gutta-percha. Canals instrumented with engine driven NiTi files exhibited less leakage than hand instrumented canals.

Rotary instrumentation of the root canals provides a superior preparation in comparison to hand instrumentation. Removal of smear layer increases the resistance of microleakage. Thermoplasticized gutta-percha obturation appears to provide a superior seal as compared to lateral condensation.

Shetty P, Uppin V, Shetty D. To Evaluate the Effect of Presence and Absence of Smear Layer with Different Instruments and Obturation Methods on Microleakage of Root Canal-Filled Teeth: An in vitro Study. World J Dent 2013;4(2):103-107.