Characterization of methacrylate-based composites containing thio-urethane oligomers

Area of Science:

• Polymer Chemistry
• Biomaterials Science
• Dental Materials

Background:

• Restorative composite resins are widely used in dentistry.
• Improving their mechanical properties and reducing polymerization stress remains a challenge.
• Thio-urethane oligomers offer a potential solution for enhanced composite performance.

Purpose of the Study:

• To evaluate the efficacy of thio-urethane oligomers in improving the properties of methacrylate-based restorative composite resins.
• To assess the impact of these oligomers on degree of conversion, mechanical properties, and polymerization stress.

Main Methods:

• Synthesis of aliphatic and aromatic thio-urethane oligomers with pendant thiols.
• Incorporation of oligomers into BisGMA-TEGDMA resin formulations with inorganic fillers.
• Photoactivation and evaluation of degree of methacrylate conversion (DC) using near-IR spectroscopy.
• Assessment of mechanical properties including flexural strength/modulus (FS/E), toughness (T), and fracture toughness (KIC) according to ISO 4049.
• Measurement of polymerization stress (PS) using the Bioman device.

Main Results:

• Thio-urethane containing composites showed a significant increase in DC, particularly with 20 wt% of the aliphatic oligomer.
• Materials with oligomers exhibited higher FS, E, and KIC compared to control groups.
• A significant reduction in PS was observed in most groups with thio-urethane addition.
• While toughness increased significantly, specific group differences were not distinguished.

Conclusions:

• Thio-urethane oligomers effectively enhance the degree of conversion, flexural strength, modulus, and fracture toughness of dental composites.
• These oligomers significantly reduce polymerization stress, a key factor in restoration longevity.
• The addition of thio-urethane oligomers presents a promising strategy to improve the performance and service life of dental composites without altering standard clinical practices.