Effect of Processing Technology on the Degradation Behavior of Poly(p-dioxanone) Cog Threads

Abstract Background PPDO cog threads are widely used in facial rejuvenation. Common barb-fabricating techniques for PPDO threads include injection molding, compression molding, and cutting. These methods subject PPDO to distinct thermal and mechanical histories, potentially altering its internal structure. However, how these structural differences affect degradation and clinical longevity remains unclear and requires systematic investigation. Objectives To investigate the influence mechanisms of three processing techniques on the in vitro degradation behavior and mechanical properties of PPDO cog threads. Methods PPDO cog threads prepared by three techniques were degraded in 37℃ PBS for 32 weeks. The mass loss rate, inherent viscosity, tensile strength, grasping force and SEM were measured periodically. Results All samples exhibited a two-stage degradation profile. In the first 8 weeks, mass loss was slow, inherent viscosity decreased rapidly, and tensile strength declined uniformly. After 8 weeks, mass loss accelerated, inherent viscosity reduction slowed, and tensile strength was largely lost. Injection-molded threads (highest processing temperature) degraded the fastest; unheated cut threads retained better molecular chain integrity for prolonged degradation; compression-molded threads had an intermediate degradation rate. For mechanical properties, cut threads had the slowest initial tensile strength loss due to no thermal damage (all three converged in later stages); injection-molded threads exhibited faster grasping force retention decline than compression-molded ones, confirming intensive thermal history accelerates degradation. Conclusions The processing technology significantly influences the degradation rate of PPDO cog threads. Rational selection of processing methods can tailor degradation behavior, providing theoretical support for choosing the optimal cog threads in clinical applications.