Graphene Oxide Nanosheets and PMMA in Dental Filler Composites: Ultrasound Behavior and Antibacterial Effects

This study investigates the enhancement of dental filler composites by incorporating graphene oxide (GO) nanosheets and poly(methyl methacrylate) (PMMA), aiming to improve both mechanical and antibacterial properties. The graphene-PMMA nanocomposites were synthesized using a combination of acoustic, solution sonication, and casting techniques. The properties of the newly developed fillers were assessed through various analytical methods. Fourier transform infrared (FTIR) spectroscopy indicated a significant interaction between the filler and the added materials, while X-ray diffraction (XRD) showed a notable change in crystalline behavior. Field emission scanning electron microscopy (FESEM) and optical microscope (OM) images revealed a homogeneous and fine dispersion of the nanomaterials within the filler matrix. The mechanical and rheological properties were also evaluated, with ultrasound measurements (ultrasonic velocity, absorption coefficient, compressibility, and bulk modulus) showing a substantial improvement. Specifically, GO enhanced the ultrasonic absorption coefficient by up to 325% compared to traditional hybrid/nano-fillers. Additionally, the viscosity and other rheological properties saw a significant increase, with GO contributing to a 57% improvement in viscosity over hybrid/nano-fillers. The antibacterial activity was assessed by measuring the inhibition zone against common dental pathogens, including Enterococcus faecalis and Staphylococcus aureus. The incorporation of GO nanosheets resulted in up to 46% greater antibacterial activity. These findings demonstrate that the addition of graphene oxide and PMMA to dental filler composites improves both their mechanical performance and antibacterial properties, offering potential advancements in dental restoration materials.