Evaluation of new coinitiators of camphorquinone useful in the radical photopolymerization of dental monomers

This work reports the design and synthesis of two new monomers with tertiary amines and four methacrylic (MBTTM) or acrylic (MBTTA) terminal unsaturations, and their evaluation as coinitiators in the photopolymerization of monomers useful in dentistry. Both monomers were characterized by FT-IR, H-1 NMR, and UV-vis spectroscopies. Experimental Bis-GMA/TEGDMA or UDMA/TEGDMA resins were formulated using camphorquinone as the photoinitiator and the MBTTM or MBTTA compounds as coinitiators. As control, resins using EDAB as coinitiator were formulated. The photopolymerizable resins formulated using the new coinitiators achieved double bond conversion values close to 40% in 30 s. Regarding polymerization rate, experimental resins formulated with MBTTM or MBTTA had lower values. The flexural strength of the experimental BisGMA/TEGDMA resins did not have statistically significant differences with the control group (p > 0.05). On the other hand, the experimental resins formulated with UDMA/TEGDMA presented higher flexural strength and elastic modulus. Finally, the cell viability test showed that none of the resins formulated with MBTTM or MBTTA as coinitiators were cytotoxic. Due to their characteristics, MBTTM and MBTTA monomers are potentially useful as coinitiators in the formulation of photopolymerizable materials for dental use.