Significant research and development in the field of biomedical implants has evoked the scope to treat a broad range of orthopedic ailments that include fracture fixation, total bone replacement, joint arthrodesis, dental screws, and others. Importantly, the success of a bioimplant depends not only upon its bulk properties, but also on its surface properties that influence its interaction with the host tissue. Various approaches of surface modification such as coating of nanomaterial have been employed to enhance antibacterial activities of a bioimplant. The modified surface facilitates directed modulation of the host cellular behavior and grafting of cell-binding peptides, extracellular matrix (ECM) proteins, and growth factors to further improve host acceptance of a bioimplant. These strategies showed promising results in orthopedics, e.g., improved bone repair and regeneration. However, the choice of materials, especially considering their degradation behavior and surface properties, plays a key role in long-term reliability and performance of bioimplants. Metallic biomaterials have evolved largely in terms of their bulk and surface properties including nano-structuring with nanomaterials to meet the requirements of new generation orthopedic bioimplants. In this review, we have discussed metals and metal alloys commonly used for manufacturing different orthopedic bioimplants and the biotic as well as abiotic factors affecting the failure and degradation of those bioimplants. The review also highlights the currently available nanomaterial-based surface modification technologies to augment the function and performance of these metallic bioimplants in a clinical setting.

Odontoblast differentiation from dental pulp stem cells (DPSCs) is involved in a cascade of key biological events for maintaining pulp-dentin homeostasis, repair and regeneration. A pulp regeneration biomaterial (mineral trioxide aggregate (MTA)) increased intracellular reactive oxygen species (ROS) levels during differentiation, ameliorating the differentiating of DPSCs into odontoblasts. Here, ceria nanoparticles (CNP) were incorporated as an insoluble antioxidant into commercially available MTA (CMTA), and the odontoblastic differentiation of human DPSCs was investigated. The CMTA was fabricated from MTA and CNP conjugation up to 4wt%, and the compressive strength, surface morphology after setting and setting time were investigated. Furthermore, the alkaline phosphatase (ALP) assay, Alizarin Red staining (ARS) and quantitative real-time polymerase chain reaction (qPCR) were performed to evaluate odontoblastic differentiation in an indirect co-culture system using inserts with pores. To reveal the underlying mechanism, the ROS levels and ion release were measured. Statistical analysis was performed by one-way analysis of variance with a Tukey post hoc test (P<0.05). CMTA significantly elevated the odontoblastic differentiation of hDPSCs measured by ALP activity, ARS, and odontoblastic gene expression, whereas the other physico-mechanical properties were relatively maintained. Upregulation of gene expression from CMTA was reversed with hydrogen peroxide. CMTA could reduce the increased intracellular ROS levels of hDPSCs by approximately 70% during differentiation, similar to when an antioxidant was used, without changing the ion release and pH of the media. CMTA could be useful dental materials for regenerating dentin-pulp complexes by instructing intracellular ROS during differentiation to achieve beneficial biological functions. This study suggests a new direction of dental nanomaterials in treating pulp-dentin complexes.