Characterization of Structural and Functional Properties of Humic Acid-Impregnated Dental Surgical Sutures

Objective: To evaluate the physicochemical and mechanical effects of humic acid treatment on silk and poly(glycolide-co-lactide) (PGLA) sutures of different sizes (3 − 0 and 4 − 0), using Fourier-transform infrared (FTIR) spectroscopy and tensile testing. Materials and Methods: Silk (non-absorbable) and PGLA (absorbable) sutures, both 3 − 0 and 4 − 0 in size, were subjected to humic acid surface treatment. Untreated counterparts served as controls. FTIR spectra were recorded to identify chemical modifications on the suture surfaces, focusing on functional group shifts and intensity variations. Tensile strength and elongation at break were assessed according to EN ISO 2062. Results: FTIR analysis showed enhanced O–H and C = O peak intensities in humic acid-treated groups, suggesting successful surface functionalization. Treated silk sutures displayed reduced tensile strength in 3 − 0 samples (p < 0,001) and 4 − 0 (p = 0.003) samples. whereas PGLA samples retained similar strength post-treatment (27.7 N vs. 27.6 N). Elongation percentages generally increased in treated silk sutures, while remaining high and consistent in PGLA groups. Conclusion: Humic acid treatment effectively alters the surface chemistry of both silk and PGLA sutures, as confirmed by FTIR. While the treatment slightly compromises mechanical strength in silk sutures, PGLA maintains structural integrity, indicating its suitability for functionalization with bioactive agents.