Synthesis and characterization of dimethacrylates containing quaternary ammonium functionalities for dental applications.
OBJECTIVE
The widespread incidence of recurrent caries highlights the need for improved dental restorative materials. The objective of this study was to synthesize low viscosity ionic dimethacrylate monomers (IDMAs) that contain quaternary ammoniums groups (antimicrobial functionalities) and are compatible with existing dental dimethacrylate-based monomers. Such monomers have the potential to copolymerize with other methacrylate monomers and produce antibacterial polymers.


METHODS
Two monomers (IDMA-1 and IDMA-2) were synthesized using the Menschutkin reaction and incorporated at 0-30% (by mass) into a 1:1 (by mass) bisphenol A glycerolate dimethacrylate (BisGMA):triethylene glycol dimethacrylate (TEGDMA) resin. Resin viscosity was quantified using rheology, and polymer degree of conversion (DC) and surface charge density were measured using Fourier transform infrared spectroscopy (FTIR) and fluorescein binding, respectively. Effects of IDMA-1 on initial attachment of Streptococcus mutans and on viability and metabolic activity (via reductase enzymes) of RAW 264.7 macrophage-like cells were quantified.


RESULTS
IDMA-1 and IDMA-2 were prepared and characterized. IDMA-1 was miscible with BisGMA:TEGDMA and slightly increased the resin viscosity and DC. As expected, polymeric surface charge density increased with increasing IDMA-1. Incorporation of 10% IDMA-1 into BisGMA:TEGDMA reduced bacterial colonization without affecting viability or metabolic activity of mammalian cells. Increasing IDMA-1 up to 30% had no additional effect on bacterial coverage, but ≥20% IDMA-1 significantly reduced macrophage density, viability, and metabolic activity. Leachables from polymers containing IDMA-1 were not cytotoxic.


CONCLUSIONS
The Menschutkin reaction provides a facile, convenient means to synthesize new monomers with quaternary ammonium groups for dental and medical applications.
Polymers Division, National Institute of Standards and Technology, Gaithersburg, MD, USA.
Joseph M
JM
Antonucci
Diana N
DN
Zeiger
Kathy
K
Tang
Sheng
S
Lin-Gibson
Bruce O
BO
Fowler
Nancy J
NJ
Lin
D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002452:Cell Count; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003764:Dental Materials / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D005452:Fluoresceins; D005456:Fluorescent Dyes; D008264:Macrophages / Q000187:drug effects; D008422:Materials Testing; D008689:Methacrylates / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D050296:Microbial Viability / Q000187:drug effects; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry* / Q000494:pharmacology; D012212:Rheology; D017550:Spectroscopy, Fourier Transform Infrared; D013295:Streptococcus mutans / Q000187:drug effects; D013499:Surface Properties; D014783:Viscosity
D000890:Anti-Infective Agents; D003764:Dental Materials; D005452:Fluoresceins; D005456:Fluorescent Dyes; D008689:Methacrylates; D011109:Polymethacrylic Acids; D000644:Quaternary Ammonium Compounds; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C049840:2-(dimethylamino)ethyl methacrylate