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Compared to fixed orthodontic appliances with brackets, thermoplastic invisible orthodontic aligners offer several advantages, such as high aesthetic performance, good comfort, and convenient oral health maintenance, and are widely used in orthodontic fields. However, prolonged use of thermoplastic invisible aligners may lead to demineralization and even caries in most patients' teeth, as they enclose the tooth surface for an extended period. To address this issue, we have created PETG composites that contain piezoelectric barium titanate nanoparticles (BaTiO3NPs) to obtain antibacterial properties. First, we prepared piezoelectric composites by incorporating varying amounts of BaTiO3NPs into PETG matrix material. The composites were then characterized using techniques such as SEM, XRD, and Raman spectroscopy, which confirmed the successful synthesis of the composites. We cultivated biofilms of Streptococcus mutans (S. mutans) on the surface of the nanocomposites under both polarized and unpolarized conditions. We then activated piezoelectric charges by subjecting the nanocomposites to 10 Hz cyclic mechanical vibration. The interactions between the biofilms and materials were evaluated by measuring the biofilm biomass. The addition of piezoelectric nanoparticles had a noticeable antibacterial effect on both the unpolarized and polarized conditions. Under polarized conditions, nanocomposites demonstrated a greater antibacterial effect than under unpolarized conditions. Additionally, as the concentration of BaTiO3NPs increased, the antibacterial rate also increased, with the surface antibacterial rate reaching 67.39% (30 wt% BaTiO3NPs). These findings have the potential for application in wearable, invisible appliances to improve clinical services and reduce the need for cleaning methods. [ABSTRACT FROM AUTHOR]

It has been recently reported that, in a rat calvarial defect model, adding endothelial cells (ECs) to a culture of bone marrow stromal cells (BMSCs) significantly enhanced bone formation. The aim of this study is to further investigate the ossification process of newly formed osteoid and host response to the poly(L-lactide-co-1,5-dioxepan-2-one) [poly(LLA-co-DXO)] scaffolds based on previous research. Several different histological methods and a PCR Array were applied to evaluate newly formed osteoid after 8 weeks after implantation. Histological results showed osteoid formed in rat calvarial defects and endochondral ossification-related genes, such as dentin matrix acidic phosphoprotein 1 (Dmp1) and collagen type II, and alpha 1 (Col2a1) exhibited greater expression in the CO (implantation with BMSC/EC/Scaffold constructs) than the BMSC group (implantation with BMSC/Scaffold constructs) as demonstrated by PCR Array. It was important to notice that cartilage-like tissue formed in the pores of the copolymer scaffolds. In addition, multinucleated giant cells (MNGCs) were observed surrounding the scaffold fragments. It was concluded that the mechanism of ossification might be an endochondral ossification process when the copolymer scaffolds loaded with co-cultured ECs/BMSCs were implanted into rat calvarial defects. MNGCs were induced by the poly(LLA-co-DXO) scaffolds after implantation, and more specific in vivo studies are needed to gain a better understanding of host response to copolymer scaffolds. [ABSTRACT FROM AUTHOR]