Antibacterial Efficiency of Amino Acids in the Management of Endodontic Biofilms: A Systematic Review

Abstract Objectives: This systematic review aims to evaluate the antibacterial potential of amino acids in managing endodontic biofilms. Methods: The protocol was registered with OSF https://doi.org/10.17605/OSF.IO/AH879 and is reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‑Analyses 2020 guidelines for systematic reviews. Comprehensive searches were performed across databases including PubMed, Scopus, and Web of Science for relevant studies published until March 2025. The inclusion criteria focused on studies investigating the antibacterial activity of amino acids against endodontic biofilms. Search strategies were developed based on the Population, intervention, comparison, and outcomes framework and incorporated Boolean operators (AND; OR) to refine results. MeSH terms such as “endodontic biofilm,” “amino acid,” and “antimicrobial activity” were employed. From an initial pool of 751 articles, seven studies met the inclusion criteria. The quality of the selected studies was appraised using the QUIN TOOL. Results: Quality assessment revealed predominantly low-to-moderate risk of bias (4 low, 2 medium, and 1 high). Specific D-amino acids, particularly D-leucine, D-tyrosine, D-tryptophan, and D-methionine, consistently disrupted E. faecalis and B. subtilis biofilms in a concentration- and timing-dependent manner. L-forms often reversed or attenuated the inhibitory effects of their D-counterparts, underscoring the stereochemical specificity of biofilm inhibition pathways. Non-proteinogenic amino acids demonstrated dose-dependent inhibition against S. aureus and methicillin resistant S. aureus biofilms. Conclusion: Amino acids tested in this systematic review exhibited antibacterial effects against endodontic biofilms either individually or synergistically, thus suggesting their potential use as adjuncts in endodontic treatment strategies and improving oral health outcomes.