Photopolymerization and properties of fluorene-based dimethacrylate monomer used as a root canal sealer

Evaluation of biocompatible monomers as substitutes for TEGDMA in resin-based dental composites

This works reports the synthesis and characterization of diallyl(5-(hydroxymethyl)-1,3-phenylene) dicarbonate (HMFBA) and 5-(hydroxymethyl)-1,3-phenylene bis(2-methylacrylate) (HMFBM) monomers and its evaluation as Bis-GMA eluents in the formulation of composite resins for dental use. The experimental materials formulated with HMFBA and HMFBM monomers presented flexural strength values similar to those of the control group formulated with Bis-GMA/TEGDMA. Regarding volumetric contraction percentage, the values obtained of experimental materials with HMFBA was 1.88% and for HMFBM was 4.15%, both lower than control resin (4.68%). In the case of double bond conversion, the resin formulated with HMFBA monomer exhibited a greater degree of conversion (87%). Besides, the DMA analyses proved that the values for T_g guarantee a good mechanical performance at body temperature. The new resins formulated with HMFBA and HMFBM monomers exhibit a cellular viability close to 100%, which indicates the absence of cytotoxicity towards fibroblastic cells.

Preparation of a Bis-GMA-Free Dental Resin System with Synthesized Fluorinated Dimethacrylate Monomers

With the aim of reducing human exposure to Bisphenol A (BPA) derivatives in dentistry, a fluorinated dimethacrylate monomer was synthesized to replace 2,2-bis[4-(2-hydroxy-3-methacryloy-loxypropyl)-phenyl]propane (Bis-GMA) as the base monomer of dental resin. After mixing with reactive diluent triethyleneglycol dimethacrylate (TEGDMA), fluorinated dimethacrylate (FDMA)/TEGDMA was prepared and compared with Bis-GMA/TEGDMA in physicochemical properties, such as double bond conversion (DC), volumetric shrinkage (VS), water sorption (WS) and solubility (WSL), flexural strength (FS) and modulus (FM). The results showed that, when compared with Bis-GMA based resin, FDMA-based resin had several advantages, such as higher DC, lower VS, lower WS, and higher FS after water immersion. All of these revealed that FDMA had potential to be used as a substitute for Bis-GMA. Of course, many more studies, such as biocompatibility testing, should be undertaken to prove whether FDMA could be applied in clinic.

Synthesis of fluorinated dimethacrylate monomer and its application in preparing Bis-GMA free dental resin

With the aim to reduce human exposure to Bis-phenol A derivatives, a novel fluorinated dimethacrylate monomer FUDMA was synthesized and mixed with triethyleneglycol dimethacrylate (TEGDMA) to prepare 2,2-bis[4-(2-hydroxy-3-methacryloy- loxypropyl)phenyl]propane (Bis-GMA) free dental resin system. Physicochemical properties, such as double bond conversion (DC), polymerization shrinkage (VS), water sorption (WS) and solubility (SL), flexural strength (FS) and modulus (FM), and fracture energy of FUDMA/TEGDMA resin system were investigated. Bis-GMA/TEGDMA resin system was used as a control. The results showed that, compared with Bis-GMA/TEGDMA resin system, FUDMA/TEGDMA had advantages like higher DC, lower VS, and higher fracture energy, but had no disadvantages. Therefore, FUDMA/TEGDMA resin system had better comprehensive physicochemical properties than Bis-GMA/TEGDMA resin system, and FUDMA had potential to be used as a substitute for Bis-GMA.

Evaluation of new tri-methacrylates as a reactive diluent in root canal sealant

In this work, a novel tri-methacrylate oligomer, GPTEMA, with three long-branched chain structures was synthesized through the reaction of glycerol propoxylate triglycidyl ether (GPTE) and methacrylic acid. The structure of GPTEMA was confirmed by FT-IR, (1)H-NMR, gel-permeation chromatography (GPC) and element analysis. The GPTEMA was used to partially or completely replace TEGDMA as reactive diluent and applied in a root canal sealant system containing Bis-GMA. The effects of GPTEMA on the polymerization behavior of Bis-GMA/TEGDMA/GPTEMA co-polymer and properties of its polymerizing product were investigated. Polymerization shrinkage, double bond conversion, glass transition temperature, flexural strength, flexural modulus, water sorption and diffusion coefficient of the Bis-GMA/TEGDMA/GPTEMA co-polymer were measured. The results illustrated that the Bis-GMA/TEGDMA/GPTEMA co-polymer attained lower polymerization shrinkage and higher double bond conversion. However, its T g, flexural strength and flexural modulus decreased with increasing content of GPTEMA, water sorption and diffusion coefficient increased with increasing content of GPTEMA.

Physicochemical properties, sealing ability, bond strength and cytotoxicity of a new dimethacrylate-based root canal sealer

BACKGROUND/PURPOSE

Resin-based root canal sealer can bond to dentin and establish a hermetic seal. The aim of this study was to evaluate the physicochemical properties, sealing ability, cytotoxicity and bond strength of a new resin-based root canal sealer (NRCS).

METHODS

The physicochemical properties were assessed by the flow, setting time, solubility, film thickness, radiopacity and dimensional changes. Sixty premolar root samples were filled with either Resilon/NRCS or Resilon/Epiphany and sectioned perpendicularly at the long axis at 2 mm below the cemento-enamel junction into 1-mm serial slices. The bond strength was tested by a universal testing machine. The glucose microleakage model was used to test the sealing ability. Elutes of NRCS and Epiphany were co-cultured with human periodontal ligament cells to test the cytotoxicity.

RESULTS

All the physicochemical properties of NRCS conformed to ISO 6876:2001(E). The root samples filled with Resilon/NRCS had significantly less leakage (p < 0.01) and greater bond strength (p < 0.001) than the Resilon/Epiphany group had. Environmental scanning electron microscopy showed that Resilon/NRCS filling material was intimately bonded to the root dentin. Although NRCS was slightly toxic to human periodontal ligament cells, its cytotoxicity was significantly less than that of Epiphany (p < 0.01)

CONCLUSION

NRCS has better physicochemical and sealing properties, as well as lower cytotoxicity and microleakage than Epiphany has.