Post-polymerization of three-dimensional printing resin using a dental light curing unit

Area of Science:

• Materials Science and Engineering
• Biomaterials and Dental Materials
• Additive Manufacturing and 3D Printing

Background:

• Post-polymerization is crucial for optimizing the physical properties of 3D printed objects made with vat photopolymerization resins.
• Conventional methods often involve dedicated desktop polymerizing units, necessitating evaluation of alternative, potentially more accessible, methods.

Purpose of the Study:

• To assess the efficacy of a handheld polywave light-emitting diode (LED) dental light-curing unit (LCU) for post-polymerizing 3D printed resins.
• To quantify the impact of the handheld LCU on microhardness and biaxial flexural strength of 3D printed resins.

Main Methods:

• 3D printed resin disks (1- and 2-mm thick) were subjected to post-polymerization using a handheld polywave LCU at 3200 mW/cm².
• Irradiation protocols included single-sided (T2, T4, T8 cycles) and double-sided (T1B1, T2B2, T4B4 cycles) treatments.
• Microhardness and biaxial flexural strength were compared against a conventional desktop unit (PC) and no post-polymerization (NC).

Main Results:

• Post-polymerization with the handheld LCU significantly influenced microhardness, with T8 and T4B4 achieving top-surface hardness comparable to PC.
• The highest bottom-surface microhardness was observed with PC, T2B2, and T4B4 treatments.
• The T4B4 protocol yielded the highest biaxial flexural strength for both 1- and 2-mm disks, comparable to the desktop unit.

Conclusions:

• Post-polymerization effectiveness, measured by microhardness and biaxial flexural strength, increases with irradiation time and dual-sided application.
• The handheld polywave LCU demonstrates potential as a viable alternative to desktop polymerization units for 3D printed resins, especially with optimized protocols.