Behavior of dental composite materials in sterilized and non-sterilized landfill leachate

Abstract

Treatment of used and unused dental resin based composites resulting from the activities of dental industries and clinics is challenging. Disposal to landfill site is commonly utilized to manage this waste. We investigated the release of monomers from dental composites in landfill leachate and the chemical changes of sterilized and non-sterilized leachate in the existence of dental composites. Solid phase micro-extraction (SPME) coupled with high performance liquid chromatography (HPLC) was used to extract and quantify the released monomers. Chemical characterization of leachate was carried out using pH meter, gas chromatography (GC), ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS). The HPLC results, revealed that Bis-GMA, TEGDMA, UDMA, HEMA and BPA monomers were released from dental composites. According to the results of pH, GC, IC and ICP-MS, the presence of dental composites has no significant effect in the chemistry of leachate except increasing the production of CH4 and CO_2. However, autoclaving increased pH values and decreased calcium concentration in sterilized samples. Furthermore, Mn^concentration increased and Fe^ concentration decreased in non-sterilized samples due to microbial activities