Comparative Evaluation of Smear Layer Removal using Edta, Citric Acid, and Maleic Acid: A Sem Study
DOI:
https://doi.org/10.48165/ajm.2026.9.02.16Keywords:
Smear Layer, EDTA, Citric AcidAbstract
Background: Effective removal of the smear layer is an important step in root canal treatment because its persistence may interfere with the penetration of disinfecting agents and the adaptation of root canal sealers to dentinal walls. Chelating agents such as ethylenediaminetetraacetic acid (EDTA), citric acid, and maleic acid have been widely investigated for smear layer removal; however, differences in their effectiveness may depend on their chemical properties and interaction with dentin. Aim: To comparatively evaluate the effectiveness of EDTA, citric acid, and maleic acid in removing the smear layer from root canal walls using scanning electron microscopy (SEM). Materials and Methods: Forty extracted human single-rooted permanent teeth will be selected and decoronated to standardize the root length. The root canals were prepared using a standardized step-back instrumentation technique with stainless-steel K-files, with sodium hypochlorite used as the irrigant during instrumentation. The specimens will then be randomly allocated into four groups (n = 10 each) according to the final irrigation protocol: Group I—17% EDTA, Group II—10% citric acid, Group III—7% maleic acid, and Group IV—distilled water (control). Following irrigation, the roots will be split longitudinally and prepared for SEM evaluation. Smear layer removal will be assessed at the coronal, middle, and apical thirds using a standardized scoring system. The scores will be statistically analyzed using appropriate statistical tests, with the level of significance set at p < 0.05. Results: SEM evaluation demonstrated significant differences in smear layer removal among the four groups (p < 0.001). The 7% maleic acid group showed the highest proportion of Score 1 specimens (70%), followed by 10% citric acid (40%) and 17% EDTA (20%), whereas the distilled-water control showed no Score 1 specimens. Smear layer removal was generally greater in the coronal third and decreased toward the apical third. Conclusion: EDTA, citric acid, and maleic acid may differ in their ability to remove the smear layer from root canal walls. SEM evaluation provides detailed morphological assessment of the dentinal surface and may help identify an effective final irrigation protocol for achieving optimal smear layer removal.
Downloads
References
Wong, J., Manoil, D., Näsman, P., Belibasakis, G. N., & Neelakantan, P. (2021). Microbiological aspects of root canal infections and disinfection strategies: An update review on the current knowledge and challenges. Frontiers in Oral Health, 2, 672887.
Usta, S. N., Solana, C., Ruiz-Linares, M., Baca, P., Ferrer-Luque, C. M., Cabeo, M., & Arias-Moliz, M. T. (2023). Effectiveness of conservative instrumentation in root canal disinfection. Clinical Oral Investigations, 27(6), 3181–3188.
Machado, R., da Silva, I., Comparin, D., de Mattos, B. A. M., Alberton, L. R., & da Silva Neto, U. X. (2021). Smear layer removal by passive ultrasonic irrigation and 2 new mechanical methods for activation of the chelating solution. Restorative Dentistry & Endodontics, 46(1), e11.
Setia, R., Bajaj, N., Bhola, M., & Brar, G. S. (2023). Comparative evaluation of smear layer removal efficacy of neem leaf extract, propolis, and orange oil when used as endodontic irrigants: An in vitro scanning electron microscopic study. Contemporary Clinical Dentistry, 14(2), 128–134.
Borzini, L., Condò, R., De Dominicis, P., Casaglia, A., & Cerroni, L. (2016). Root canal irrigation: Chemical agents and plant extracts against Enterococcus faecalis. The Open Dentistry Journal, 10, 692–703.
Kaur, M., Singla, M., Kaur, H., Mittal, L., Gupta, S., & Joseph, M. M. (2024). Comparative evaluation of smear layer removal by using different irrigant activation techniques: An in vitro scanning electron microscopic study. Journal of Conservative Dentistry and Endodontics, 27(3), 257–261.
Dewi, A., Upara, C., Chaiariyakul, D., & Louwakul, P. (2020). Smear layer removal from root canal dentin and antimicrobial effect of citric acid-modified chlorhexidine. European Endodontic Journal, 5(3), 257–263.
Dave, A. G., Mallya, P. L., Ballal, N. V., & Shenoy, R. (2023). Effect of ethylenediaminetetraacetic acid, maleic acid, and fumaric acid on postendodontic treatment root fracture toughness: An in vitro study. Journal of Conservative Dentistry and Endodontics, 26(4), 453–457.
Torabinejad, M., Khademi, A. A., Babagoli, J., Cho, Y., Johnson, W. B., Bozhilov, K., Kim, J., & Shabahang, S. (2003). A new solution for the removal of the smear layer. Journal of Endodontics, 29(3), 170–175.
Mello, I., Kammerer, B. A., Yoshimoto, D., Macedo, M. C., & Antoniazzi, J. H. (2010). Influence of final rinse technique on ability of ethylenediaminetetraacetic acid of removing smear layer. Journal of Endodontics, 36, 512–514.
Yamada, R. S., Armas, A., Goldman, M., & Lin, P. S. (1983). A scanning electron microscopic comparison of a high volume final flush with several irrigating solutions: Part 3. Journal of Endodontics, 9, 137–142.
Kuruvilla, A., Jaganath, B. M., Krishnegowda, S. C., Ramachandra, P. K., Johns, D. A., & Abraham, A. (2015). A comparative evaluation of smear layer removal by using EDTA, etidronic acid, and maleic acid as root canal irrigants: An in vitro scanning electron microscopic study. Journal of Conservative Dentistry, 18(3), 247–251.
Ballal, N. V., Kandian, S., Mala, K., Bhat, K. S., & Acharya, S. (2009). Comparison of the efficacy of maleic acid and ethylenediaminetetraacetic acid in smear layer removal from instrumented human root canal: A scanning electron microscopic study. Journal of Endodontics, 35, 1573–1576.
Prabhu, S. G., Rahim, N., Bhat, K. S., & Mathew, J. (2003). Comparison of removal of endodontic smear layer using NaOCl, EDTA and different concentrations of maleic acid: A SEM study. Endodontology, 15, 20–25.
Oh, S., Perinpanayagam, H., Lee, Y., Kum, J. W., Yoo, Y. J., Lim, S. M., Chang, S. W., Shon, W. J., Lee, W., Baek, S. H., & Kum, K. Y. (2016). Effect of acidic solutions on the microhardness of dentin and set OrthoMTA and their cytotoxicity on murine macrophage. Restorative Dentistry & Endodontics, 41(1), 12–21.
