Effectiveness of different irrigation systems on smear layer removal: A scanning electron microscopic study

Area of Science:

• Endodontics
• Dental Materials Science
• Biomaterials

Background:

• Smear layer (SR) removal is crucial for effective root canal disinfection and sealing.
• Various irrigation systems exist, including apical negative pressure irrigation (EndoVac), passive ultrasonic irrigation (PUI), and conventional needle irrigation (CI).
• The effectiveness of these systems in conjunction with different irrigants needs thorough evaluation.

Purpose of the Study:

• To compare the efficacy of EndoVac, PUI, and CI systems in removing the smear layer (SR).
• To assess the role of sodium hypochlorite (NaOCl) alone versus NaOCl combined with ethylenediaminetetraacetic acid (EDTA) in SR removal.
• To determine the optimal irrigation strategy for comprehensive smear layer debridement.

Main Methods:

• Sixty single-rooted canine teeth were instrumented using NiTi rotary files.
• Teeth were irrigated with either NaOCl alone or NaOCl/EDTA using EndoVac, PUI, or CI systems.
• Roots were longitudinally sectioned, and scanning electron microscopy (SEM) was used to evaluate residual SR.

Main Results:

• Irrigation with NaOCl alone (Groups 1, 3, 5) showed no significant SR removal.
• The combination of NaOCl/EDTA (Groups 2, 4, 6) resulted in partial to complete SR removal in coronal, middle, and apical thirds.
• No statistically significant difference was observed in SR removal between the irrigation systems when using NaOCl/EDTA.

Conclusions:

• Sodium hypochlorite (NaOCl) alone is ineffective for smear layer (SR) removal in root canal treatment.
• The addition of ethylenediaminetetraacetic acid (EDTA) to NaOCl significantly enhances SR removal.
• EDTA solution is essential for final irrigation to achieve effective smear layer removal, irrespective of the irrigation technique used.