Development of suture thread based on cellulose acetate prepared through filament extruder for dental use

This study investigated the fabrication and characterization of biodegradable monofilament suture threads based on cellulose acetate (CA), plasticized with triethyl citrate (TC) and reinforced with poly(lactic acid) (PLA), produced by twin-screw micro-extrusion for potential dental surgical applications. The effects of TC content (25, 30, and 35 wt%) and PLA incorporation (15 wt%) on processability, thermal behavior, morphology, mechanical properties, and biocompatibility were systematically evaluated. The sutures were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile testing, and in vitro biological assays using RAW 264.7 macrophages. The results showed that TC effectively reduced the glass transition temperature of CA, enhancing flexibility and processability, while PLA incorporation influenced thermal stability and promoted morphological changes, including increased porosity and elasticity. SEM analyses revealed smooth and homogeneous surfaces for CA/TC monofilaments and slightly rougher, more porous morphologies for CA/PLA/TC blends, which may favor tissue interaction. In vitro assays confirmed cytocompatibility, with no cytotoxic effects or nitric oxide induction observed over a 7-day exposure period. Although most formulations did not fully meet the tensile strength requirements specified by NBR 13904/2003, the formulation containing 25 wt% TC and 15 wt% PLA (A4) exhibited the best mechanical performance, approaching normative values while maintaining suitable handling characteristics. Overall, the results indicate that CA/TC/PLA-based sutures represent a promising, sustainable, and biocompatible alternative for absorbable surgical sutures, although further optimization is required to fully comply with mechanical regulatory standards.