Current applications and future perspectives on rare-earth-based materials in stomatology

Abstract

A confluence of factors, including the incompatibility of conventional materials with the oral environment, inadequate dynamic response, and insufficient multi-objective synergy, hinders precise diagnosis and efficient treatment in contemporary stomatology. Due to their unique electronic configuration and multivalent properties, rare earth elements (REEs) have shown excellent optical response, enzyme simulation activity, antibacterial efficacy, and biological regulation potential. These attributes offer a promising path for developing a new generation of oral functional materials. To align the unique properties of REEs and the clinical demands, this article summarizes the current knowledge of physicochemical properties and biological functions of REEs, and provides a comprehensive overview of the cutting-edge applications of rare-earth-based materials in oral medicine. We anticipate that this review will enhance the understanding of the interdisciplinary value of rare-earth-based materials in stomatology, thereby contributing to the improvement of future oral healthcare.

Keywords: Biomedical materials; Health sciences; Materials science.

Graphical abstract

Figure 1

The catalytic principle of Ce Ce possesses both superoxide dismutase (SOD) and catalase (CAT) activities. Under physiological conditions, it is capable of effectively clearing ROS. In an acidic pH environment, the SOD activity of Ce is significantly enhanced, which leads to an accumulation of H₂O₂, and inflicts damage upon cells.

Figure 2

The mechanism of REEs in promoting osteogenesis REEs promote osteogenic differentiation, cell proliferation, and cell migration by affecting the (A) BMP/Smad and (B) Wnt/β-catenin signaling pathways. BMP, bone morphogenetic protein; BMPR, bone morphogenetic protein receptor; TGF-β, transforming growth factor β; Smad, small mothers against decapentaplegic; Wnt, wingless-type MMTV integration site family. Adapted with permission from Chen et al.

Figure 3

Synergistic antibacterial effects of REEs in functional materials Confocal laser scanning microscopy (A) and scanning electron microscopy (B) revealed that La@PCDs (composites of lanthanum and CQD-PVA) were significantly more effective than LaNPs and 5% NaClO in removing Enterococcus faecalis biofilm in vitro. In the La@PCDs group, the biofilm was effectively removed, and most of the bacteria were killed, with no significant erosive damage observed on the dentin of the root canal wall. Reproduced with permission from Yu et al. Copyright 2024, Dove Medical Press Limited.

Figure 4

The anti-inflammatory effects of REEs in composite materials (A) A Janus nano-motor by coating cerium dioxide-doped mesoporous silica with gold nanoparticles, in which CeO₂ exerts antioxidant and anti-inflammatory effects by inducing the polarization of macrophages toward the M2 phenotype, thereby creating a favorable environment for the regeneration of periodontal bone tissue. Adapted with permission from Bai et al. (B) The nanocomposite CeO₂@Ce6, in which CeO₂ scavenges excessive ROS beyond the antimicrobial requirements, thereby preventing the exacerbation of periodontal inflammation. Adapted with permission from. Copyright 2021, Elsevier. (C) A mussel-bioinspired implant abutment coating containing tannic acid, cerium and minocycline. The conversion between Ce³⁺ and Ce⁴⁺ exhibits mimetic enzyme activity, scavenging ROS and promoting the polarization of anti-inflammatory M2 macrophages, thereby helping to create a regenerative environment and prevent peri-implantitis. Adapted with permission from Li et al. Copyright 2023, Wiley. (D) Self-assembled Ce-substituted molybdenum blue nanowheel crystals are synthesized and loaded onto 3D-printed bioactive glass scaffolds, in which Ce effectively scavenges ROS, thereby protecting normal tissues during the photothermal treatment of osteosarcoma. Adapted with permission from Lu et al. Copyright 2024, Wiley.

Figure 5

Rare-earth-modified implants facilitate osseointegration Microcomputed tomography (A and B) and histological section staining (C and D) revealed that the amount of bone surrounding Ce-MBGNs-modified implants was significantly higher than that of the control group. The results showed more new bone formation around the implants and a significant reduction in the number of inflammatory cells, suggesting that the Ce-MBGNs-modified implants exhibit a favorable osseointegration effect. Adapted with permission from Jiang et al.