METABOLIC ALTERATIONS INDUCED BY METHACRILIC MONOMERS IN HUMAN PULPAR FIBROBLASTS

Aim: Composite resins were introduced in the 1960s for the restoring of anterior teeth in substitution of the amalgam that presented both aesthetical and biocompatibility problems. However, since the polymerization of methacrylates is never complete, the need to appraise the biocompatibility of composite resins became evident. The incomplete conversion causes in fact the release of monomers that may implement adverse effects in the organism, i.e. allergic reaction, systemic toxicity, cytotoxicity. Given that very little information has been so far delivered on the effects of methacrylic monomers on cell metabolism, the aim of this work was the evaluation of the biochemical interactions between methacrylates and human fibroblasts. Methods: The effects of triethylenglycol-dimethacrylate (TEGDMA), 2-hydroxyhethyl methacrylate (HEMA), and 1,4-butanediol dimethacrylate (BDDMA) on 1) cellular energetic metabolism (oxygen consumption rate, glucose consumption, G6PDH, lactate production) 2) cellular redox status (GSH concentration, the activity of the enzymes regulating glutathione metabolism and REDOX status of cells) were analysed according to Nocca et al. Data are expressed as the mean ± statistical error of the mean (SEM). The means were compared by analysis of variance (ANOVA) followed, when appropriate, by a multiple comparison of means by Student-Newman-Keuls test: p < 0.05 was considered significant. Results: The results showed that TEGDMA, HEMA and BDDMA induce a statically significant decrease of oxygen consumption, an enhancement of glucose consumption, lactate production and also GSH depletion. Conclusions: The alterations in energy metabolism, REDOX status and glutathione balance – produced in the cellular metabolism by HEMA, TEGDMA and BDDMA – can be considered among the mechanisms inducing the clinical and sub-clinical adverse effects that have been occasionally reported during the use of dental resins. In our opinion, such investigations can therefore be helpful to test the behavior of materials especially designed to be applied inside the human body. Nocca G, De Palma F, Minucci A, et al. Alterations of energy metabolism and glutathione levels of HL-60 cells induced by methacrylates present in composite resins. J Dent 2007;35:187-94.