The Effect of Four Commonly Used Root Canal Irrigants on the Removal of Smear Layer: An In-Vitro Scanning Electron Microscope Study

Abstract

Introduction: To achieve a thoroughly clean root canal, mechanical instrumentation, supplemented with irrigants, and intracanal medications are employed. Irrigants play a vital role in the removal of the smear layer. Hence in the present study we intend to compare the efficiency of four commonly used chemicals in their ability to remove smear layer after instrumentation using scanning electron microscope (SEM).

Methods: 50 single-rooted, freshly removed human mandibular premolars were taken. They were separated into the equal groups of 10 each with a control group. After performing the access opening and gaining the access to the canals and the lengths measured, Irrigation was performed. The roots were then split with a hammer and chisel. One-half of each tooth was selected and prepared for SEM examination. After assembly on coded stubs, the specimens were placed in a vacuum chamber and sputter-coated with a 300 Å gold layer. The specimens were then analyzed using a Philips SEM XL 30. The dentinal wall of the 1,3,5 mm from apex was observed at magnifications of up to ×1000 for the presence/absence of smear layer and visualization of the entrance to dentinal tubules. Photomicrographs (×1000) of these area were made. Data were analyzed using statistical tools keeping p value less than 0.05.

Results: SEM study done on these prepared teeth with the popularly used four chemicals, namely, 3% NaOCl (Group 1), 3% NaOCl followed by 17% ethylene diamine-tetra-acetic acid (Group 2), 0.2% chlorhexidine (Group 3) and 3% NaOCl followed by MTAD (Group 4), with distilled water (Group 5) which is used as control, revealed that NaOCl showed statistically significant, better cleansing effect than distilled water. Chlorhexidine and NaOCl showed equal kind of efficacy but were statistically significant, with lower efficacy than MTAD. It may be concluded that MTAD appears to be the most effective solution compared to the rest.

Conclusion: The study demonstrated that MTAD as a final rinse after the entire instrumentation with 3% NaOCl as irrigant provided the best cleansing in all parts of the root canal system.