Influence of Fluorinated Divinyl Urethane Monomers on Resin Composite Chemical Biostability and Physical Properties

Lagowski, Michael 1 ;  Shiguetomi, Ken 1 ;  Finer, Yoav 1, 2 ;  Santerre, J. Paul 1, 2

1. Institute of Biomaterials and Biomedical Engineering; 2. Faculty of Dentistry

Background: The interfacial reaction of salivary enzymes with composite resins contribute to the loss of material composite integrity, increased surface roughness of the restoration, and release of degradation products that affect cariogenic bacterial virulence, suggesting that improving the composite’s biochemical stability and physical integrity is paramount to the success of restorative materials.

Objective: To enhance the biochemical stability by incorporating fluorinated di-vinyl urethane monomers into resin composite formulations, while ensuring that mechanical strength is not compromised. 

Methods: Synthesis of fluorinated divinyl urethane monomers is achieved by reacting 2x lysine diisocyanates with a low molecular weight diol and 2x perfluoro-mono-alcohols to yield a monomer precursor. Following the hydrolysis of the OCH3 groups on LDI, 2x 2-hydroxyethyl methacrylates are covalently coupled to form the final divinyl monomer. Perfluoroalcohols and low molecular weight diols are varied to generate composite formulations to improve biochemical stability against hydrolysis while maintaining optimal mechanical properties. Standard barium borosilicate glass filler (65wt% total) is used as a filler system. Monomers are characterized by nuclear magnetic resonance (1H-NMR) and mass spectrometry. Composites made from a mixture of monomers (35wt% total), including bisphenol A glycidyl methacrylate (bis-GMA) and urethane dimethacrylate along with filler will be assessed for flexural and compressive strength. Composite surfaces will be analyzed via contact angle analysis and water uptake testing to determine material hydrophobicity. Candidate composites will be assessed for clinically-relevant properties such as viscosity and wear. In relation to the main objective of the study, composite formulations with superior physical properties will then be assessed for their biodegradation resistance when subjected to a simulated human salivary esterase solution for up to 28 days. The corresponding release profiles for the bis-GMA derived biodegradation product 2,2-Bis[4(2,3-hydroxypropoxy)phenyl]propane (bis-HPPP) will be quantified by high-performance liquid chromatography (HPLC).

Results: 11 different fluorinated divinyl urethane monomers were synthesized with % yields of 31 to 54%, and characterized by 1H-NMR. Of the 11, 8 monomers could be successfully reproduced and will be further studied as described above. Preliminary biodegradation and HPLC results show improved resistance to hydrolysis.

Conclusions: The reproducibility of novel fluorinated monomers synthesis and formulation into related composites with practical physical and biochemical properties was shown.

Significance/Impact: The work is an important step towards generating more hydrolytically stable monomers composites for use in clinical restorative dentistry.