This work is licensed under Creative Commons Attribution–NonCommercial International License
(CC BY-NC 4.0).
Background: Effective smear layer removal is crucial for enhancing root canal disinfection and sealing. Traditional
chelators like ethylenediaminetetraacetic acid (EDTA) are widely used; however, alternative agents such as fumaric acid, malic acid, and hyaluronic acid are being explored for their biocompatibility and efficacy.
Objectives: This in vitro study compared the smear layer removal capabilities of these agents using scanning electron
microscopy (SEM).
Materials and Methods: Fifty extracted human single-rooted teeth with straight, fully formed canals were selected. Teeth with caries, fractures, or calcifications were excluded. Specimens were instrumented using the ProTaper Universal system and randomly divided into five groups (n = 10) based on the final irrigant used: 5% fumaric acid, 17% EDTA, 7% malic acid, 0.12 % hyaluronic acid, and distilled water (control). After irrigation, roots were longitudinally split, and SEM images were captured at coronal, middle, and apical thirds (×1000) and scored using Hülsmann’s criteria by a blinded observer and AI-assisted analysis.
Results: Fumaric acid and EDTA demonstrated superior smear layer removal across all canal levels (p < 0.001), with no significant difference between them. Malic acid showed moderate efficacy, while hyaluronic acid and saline were largely ineffective. Cleaning efficacy consistently decreased from coronal to apical regions for all irrigants. Inter-observer reliability between human and AI scoring was fair to moderate (κ = 0.385, p < 0.001).
Conclusion: Fumaric acid (5%) and EDTA (17%) are the most effective agents for smear layer removal, outperforming
malic acid and hyaluronic acid. Fumaric acid presents a promising, biocompatible alternative to EDTA for final root canal irrigation. Further clinical studies are recommended to validate these findings.