Genotoxicity of dental resin polymerization initiators in vitro

Abstract

The polymerization initiators for resins cured using visible light usually consist of a photosensitizer, primarily camphorquinone (CQ), and a reducing agent, which is often a tertiary amine (DMPT, DMAEMA), while the initiator used for self-curing resins consists of benzoyl peroxide (BPO) and a tertiary amine (DMPT). The genotoxicities of camphorquinone (CQ), benzoyl peroxide (BPO), dimethyl-para-toluidine (DMPT), 2-dimethylamino-ethyl-methacrylate (DMAEMA), and 1-allyl-2-thiourea (ATU) were examined using the bioluminescent bacterial genotoxicity test. 4-Nitroquinoline-N-oxide (4NQO) was prepared for comparison with these chemicals. Acetone solutions of the five polymerization initiators and 4NQO were prepared. Benzoyl peroxide (BPO), dimethyl-para-toluidine (DMPT), and 1-allyl-2-thiourea (ATU) showed significant genotoxic activity at 24 h in the bioluminescent bacterial genotoxicity test, at concentrations of approximately 5 microM, 4 mM, and 1 mM, respectively. 2-Dimethyloamino-ethyl-methacrylate (DMAEMA) did not have genotoxic activity and CQ had questionable genotoxic activity. In comparison, 4NQO had strong genotoxicity, at 4 microM, roughly the same as that of BPO. Therefore, BPO should be used carefully in clinical dentistry.

Apototic and Necrotic Influence of Dental Resin Polymerization Initiators in Human Gingival Fibroblast Cultures

“…For example, BPO is found to be estrogenic and genotoxic in vitro 8) . Although DMPT and CQ are not genotoxic, the metabolic products of DMPT are estrogenic 15,26) . Dental resins usually contain about 0.2-1.5 wt％ of polymerization initiator relative to the monomer 9).…”

Influence of Different Concentration and Ratio of a Photoinitiator System on the Properties of Experimental Resin Composites

“…Also, an incomplete photocuring process leaves the composite with more leachable residual monomers and initiators that can increase its biological incompatibility and jeopardize the color stability (11,12). Therefore, it is important to find an optimal photoinitiator and co-initiator concentration and ratio that guarantee a satisfactory polymerization behavior and consequently better chemical-mechanical properties without increasing the yellowing of the composite restorations.…”

Can CQ Be Completely Replaced by Alternative Initiators in Dental Adhesives?

“…As for amines, they are known to form byproducts during photoreaction, which also tend to cause yellow to red/brown discolorations under the influence of light or heat 5) . Apart from the aesthetical aspect, biocompatibility -and conversely toxicity and mutagenicity -are also the concerns and reservations connected with the use of amines compounds for dental applications [6][7][8] . Another area of concern stems from the potential degradation of the initiation system in aggressive conditions such as the low pH of self-etching enameldentin adhesives.…”