Development of Antimicrobial Monomer Systems

Objective: Current applications of antimicrobial agents in dental restorative materials are primarily limited to fluoride use in glass ionomer cements (GICs) or resin-modified GICs. In these systems however, a continuous and constant release of fluoride is difficult to attain over prolonged periods since diffusion based systems, such as GICs, deplete their release early in the implant life. By chemically incorporating antimicrobials into polymer resins, the diffusion limitations may be overcome. The objective of this study was to incorporate antibiotics into the monomer component of restorative polymer system, allowing for a more constant and controlled release of the antibiotic component. This was conceived in a manner that promoted longevity of the material and it’s antibiotic properties.

Method: A model antimicrobial, Ciprofloxacin (CF) was reacted with triphenyl chloride in dry chloroform, in the presence of triethylamine for a period of five hours to protect active functional groups. Methanol was subsequently added to deprotect the carboxylic acid group. (N)-trityl-Ciprofloxacin was consequently reacted with triethylene glycol, using 4-dimethylaminopyridine (DMAP) and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) as catalysts in dichloromethane under dry conditions for ten days. The product was isolated and reacted with trifluoroacetic acid in chloroform, in the presence of water for four hours to release the secondary amine groups. The deprotected product was then reacted with methacrylic acid in the presence of EDC and DMAP in N,N-dimethylformamide under dry conditions for five days.

Result: The final monomer was successfully synthesized (approximately 37% yield) and structures confirmed by ¹H and ¹⁹F NMR. Although initial polymerization studies have begun, optimization of the polymerization conditions is still ongoing. Similarly, characterization of the resulting polymers’ physical and chemical properties and antibiotic release rate is still in progress.

Conclusion: The synthesis of a novel antimicrobial monomer was successful.