Polymerization contraction and conversion of light-curing BisGMA-based methacrylate resins

Area of Science:

• Polymer Chemistry
• Dental Materials Science

Background:

• Bisphenol-A bis(2-hydroxypropyl)methacrylate (BisGMA) is a common resin base in dental restorative materials.
• Diluents are often added to BisGMA to improve handling properties and reduce viscosity.
• Understanding polymerization contraction and conversion is crucial for material performance and longevity.

Purpose of the Study:

• To investigate the effect of different diluting monomers on polymerization contraction and conversion of BisGMA-based resins.
• To evaluate triethylene glycol dimethyacrylate (TEGDMA), methyl methacrylate (MMA), hydroxypropyl methacrylate (HPMA), and (+/-)-2-ethylhexyl methacrylate (EHMA) as diluents.
• To correlate linear polymerization contraction with monomer conversion.

Main Methods:

• Synthesis of BisGMA-based resin mixtures with varying concentrations of diluents (TEGDMA, MMA, HPMA, EHMA).
• Measurement of linear polymerization contraction using a linometer at ambient temperature.
• Estimation of monomer conversion based on measured contraction values.

Main Results:

• Polymerization contraction increased proportionally with the concentration of the added diluting monomer.
• The estimated conversion for BisGMA-TEGDMA mixtures aligned with existing literature values.
• BisGMA-HPMA mixtures exhibited high monomer conversion alongside moderate polymerization contraction.

Conclusions:

• The choice of diluting monomer significantly impacts the polymerization contraction and conversion of BisGMA-based resins.
• HPMA appears to be a promising diluent, offering high conversion with manageable contraction.
• These findings provide valuable insights for formulating dental resins with optimized properties.