Diane R Bienek
ADA Foundation, USA
Title: Multifunctional polymeric materials for dental restorations
Biography
Biography: Diane R Bienek
Abstract
Statement of the Problem: Polymeric resin-based materials are commonly used in dental restorations. A trend for the next generation is to incorporate multifunctional capabilities to regulate microbial growth and re-mineralize tooth surfaces. Our ongoing, NIDCR-supported research (DE026122) focuses on simultaneous incorporation of novel quaternary ammonium antimicrobial acrylic co-monomer (QA-MA) and bioactive amorphous calcium phosphate (ACP) filler into urethane-based (UDMA) resins. While a sustained release of re-mineralizing calcium (Ca) and phosphate (P) ions is a desired feature in restoratives, the potential leaching of unreacted monomers and other products can lead to clinical failure. We assessed Ca and P ion release (remineralization potential) of ACP filler and in vitro cytotoxicity of QA-MA in gingival cells.
Methodology: ACP and Bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide (IDMA) were synthesized and their structure confirmed by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis (XRD), and/or 1H-nuclear magnetic resonance spectroscopy (1H-NMR). Ion release studies employed inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Direct contact cytotoxicity tests were performed per ISO10993-5. Gingival fibroblasts (HGF) and keratinocytes (Gie-No3B11) were exposed to two-fold serial dilutions of IDMA (≤1.6 μmol) and methacrylic acid (≤12 mM) as a degradation product. After 24 and 72 h, cells were assessed for viability and metabolic activity.
Findings: The ACP filler and IDMA were successfully synthesized and characterized by XRD/FTIR/ICP-AES and FTIR/NMR, respectively. A desired remineralization potential of ACP fillers has been achieved: supersaturated solutions with Ca/P of 1.66 are conducive to tooth mineral re-deposition (Fig. 1). IDMA concentration did not exert a significant effect on HGF viability or metabolic activity (Fig. 2). However, an effect (P<0.001) of time was observed on metabolic activity (~20% lower after 72 h).
Conclusion & Significance: ACP and IDMA were successfully synthesized. Bio-testing prior to comprehensive physicochemical and mechanical evaluations ensures that the QA-MA’s potential cytotoxicity is carefully balanced with the antibacterial activity.