Dental Materials
Volume 25, Issue 3 , Pages 302-313, March 2009

Synthesis and evaluation of modified urethane dimethacrylate resins with reduced water sorption and solubility

  • Ronald E. Kerby

      Affiliations

    • Division of Restorative and Prosthetic Dentistry, The Ohio State University, College of Dentistry, Columbus, OH 43210, United States
    • Corresponding Author InformationCorresponding author at: Division of Restorative and Prosthetic Dentistry, The Ohio State University, College of Dentistry, Room 3005B, 305 West 12th Avenue, Columbus, OH 43210, United States. Tel.: +1 614 292 0880; fax: +1 614 292 9422.
    • ,
  • Lisa A. Knobloch

      Affiliations

    • Division of Restorative and Prosthetic Dentistry, The Ohio State University, College of Dentistry, Columbus, OH 43210, United States
    • ,
  • Scott Schricker

      Affiliations

    • Division of Restorative and Prosthetic Dentistry, The Ohio State University, College of Dentistry, Columbus, OH 43210, United States
    • ,
  • Benjamin Gregg

      Affiliations

    • Private Orthodontic Practice, Ashland, OH, United States

Received 12 May 2008; received in revised form 8 July 2008; accepted 17 July 2008.

Abstract 

Objectives

New aliphatic and aromatic urethane dimethacrylate monomers containing pendant phenyl methoxy or ethyl substituents were synthesized in order to reduce the water sorption and solubility of urethane dimethacrylate systems. Selected properties including flexural strength, flexural modulus, water sorption and solubility, and water contact angle were evaluated. Hoy's solubility parameters were also calculated to rank copolymer hydrophilicity.

Methods

Filled (20%) composite resins were formulated with each of the newly synthesized dimethacrylates as well as the commercially available urethane dimethacrylate monomer, UDMA. Flexural strength, flexural modulus, water sorption and solubility of the urethane composites were evaluated after light-cured specimens were immersed in water for seven days. Water contact angles were measured on the surface of each material. Data were analyzed using ANOVA and Ryan–Einot–Gabriel–Welsch multiple range tests (α=0.05).

Results

A significant reduction of nearly 30% and 40% in water uptake was observed with composite polymers containing pendant ethyl and phenyl methoxy groups, respectively, compared to UDMA (p<0.05). Urethane copolymers containing pendant ethyl groups also showed a significant reduction in water solubility (p<0.05). A positive correlation was found between contact angle and water sorption as well as Hoy's δh for hydrogen bonding forces.

Significance

The results of this study indicate that the incorporation of pendant hydrophobic substituents within the monomer backbone may be an effective method in reducing the water sorption and water solubility of urethane based dimethacrylate systems. The use of Hoy's solubility parameters to determine the relative hydrophilicity of a polymer may be limited by its three-dimensional chemical structure.

Keywords: Dental resin, Dimethacrylate, Urethane, Composite, Water sorption, Solubility, Solubility parameters, Mechanical properties, Hydophilic, Hydrophobic

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PII: S0109-5641(08)00200-5

doi:10.1016/j.dental.2008.07.009

Dental Materials
Volume 25, Issue 3 , Pages 302-313, March 2009

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