Synthesis of polymethyl methacrylate/depolymerized polyethylene terephthalate blend reinforced by titanium dioxide nanoparticles for dental fillings applications

Abstract

The aim of this study is to use recycled waste materials to modify the performance of composites used as dental fillings. For this purpose, depolymerized polyethylene terephthalate (DPET) polymers were prepared by recycling waste polyethylene terephthalate (PET) using the glycolysis process. DPET was then blended with polymethyl methacrylate (PMMA) at different weight percentages. Polymer blends were subjected to mechanical, physical, and biological tests. It is evident that PMMA blended with a 5 wt% of DPET exhibits the highest compressive strength which is approximately two times that obtained from neat PMMA, highlighting the suitability of these resins to replace amalgam and to be considered for dental restorations. It was also found that the water absorption of the blends investigated is relatively stable at 5 wt% DPET. The SEM images showed no distinguishable phases, highlighting the high compatibility between DPET and PMMA. The biological tests, including in vitro cytotoxicity, showed that the cell viability mean values of PMMA containing 5 wt% DPET is higher than that of control group. Interestingly, in dental practice, the reliable in vitro cytotoxic approach is considered as an important aid in clinical procedures in the use of dental filling systems. The microbiology study has shown that the inhibition zones against Streptococcus mutans of PMMA: 5 wt% DPET is higher than the control group. According to the obtained results, the blend of PMMA: 5 wt% DPET was selected as an optimum blend, which was then reinforced with various weight percentages of nano-sized titanium dioxide (TiO2). The composites were then tested under compression, microhardness, and impact tests. The results demonstrated the significant impact of TiO2 on enhancing the properties of the composites investigated. This can provide a new protocol for synthesizing nanocomposite materials for dentistry.