Research progress on the biological modifications of implant materials in 3D printed intervertebral fusion cages

Anterior spine decompression and reconstruction with bone grafts and fusion is a routine spinal surgery. The intervertebral fusion cage can maintain intervertebral height and provide a bone graft window. Titanium fusion cages are the most widely used metal material in spinal clinical applications. However, there is a certain incidence of complications in clinical follow-ups, such as pseudoarticulation formation and implant displacement due to nonfusion of bone grafts in the cage. With the deepening research on metal materials, the properties of these materials have been developed from being biologically inert to having biological activity and biological functionalization, promoting adhesion, cell differentiation, and bone fusion. In addition, 3D printing, thin-film, active biological material, and 4D bioprinting technology are also being used in the biofunctionalization and intelligent advanced manufacturing processes of implant devices in the spine. This review focuses on the biofunctionalization of implant materials in 3D printed intervertebral fusion cages. The surface modifications of implant materials in metal endoscopy, material biocompatibility, and bioactive functionalizationare summarized. Furthermore, the prospects and challenges of the biofunctionalization of implant materials in spinal surgery are discussed.

Influence of cold atmospheric plasma on dental implant materials — an in vitro analysis

Background and objectives Alterations in the microenvironment of implant surfaces could influence the cellular crosstalk and adhesion patterns of dental implant materials. Cold plasma has been described to have an influence on cells, tissues, and biomaterials. Hence, the mechanisms of osseointegration may be altered by non-thermal plasma treatment depending on different chemical compositions and surface coatings of the biomaterial. The aim of the present study is to investigate the influence of cold atmospheric plasma (CAP) treatment on implant surfaces and its biological and physicochemical side effects. Materials and methods Dental implant discs from titanium and zirconia with different surface modifications were treated with CAP at various durations. Cell behavior and adhesion patterns of human gingival fibroblast (HGF-1) and osteoblast-like cells (MG-63) were examined using scanning electron microscopy and fluorescence microscopy. Surface chemical characterization was analyzed using energy-dispersive X-ray spectroscopy (EDS). Quantitative analysis of cell adhesion, proliferation, and extracellular matrix formation was conducted including real-time PCR. Results CAP did not affect the elemental composition of different dental implant materials. Additionally, markers for cell proliferation, extracellular matrix formation, and cell adhesion were differently regulated depending on the application time of CAP treatment in MG-63 cells and gingival fibroblasts. Conclusions CAP application is beneficial for dental implant materials to allow for faster proliferation and adhesion of cells from the surrounding tissue on both titanium and zirconia implant surfaces with different surface properties. Clinical relevance The healing capacity provided through CAP treatment could enhance osseointegration of dental implants and has the potential to serve as an effective treatment option in periimplantitis therapy.

PEEK as a Potential Material for Dental Implants and its Biomechanical Properties and Osteoblast Cell Response

Proper osseointegration is crucial for the success of dental and orthopedic implants. Titanium-6Aluminum-4Vanadium (TAV) is one of the most popular implant materials; however, polyetheretherketone (PEEK) has gained the interest of implant researchers and manufacturers over the past several years due to its lower modulus of elasticity compared to metallic implant materials. Porosity and patterned surface morphologies are thought to improve mechanical interlocking and play an important role in the differentiation of pre-osteoblasts into mature osteoblasts. This study aimed to determine the effects a macro patterned PEEK surface has on the material’s mechanical properties and the proliferation, differentiation, and maturation of pre-osteoblasts. Mechanical testing data indicated that the macro patterning improved the mechanical interlocking and has no detrimental effect on compression strength. DNA data and live/dead imaging showed that pre-osteoblasts on solid PEEK specimens did not readily differentiate but instead encouraged proliferation only. However, ALP data in comparison to the DNA data showed that cells on patterned PEEK specimens more readily entered the differentiation pathway to mineralization. This is further confirmed by the patterned PEEK specimens showing an overall higher amount of cell mineralization. Clinical significance: This study concludes that surface macro patterning of PEEK material increases the mechanical interlocking and enhances the osseointegration capability without diminishing mechanical properties.

Magnetic Remanence of Stainless Steel and Titanium Alloy Orthopaedic Implants

Stainless steel and titanium alloys are common materials for orthopaedic implants. However there is a lack of information and studies on magnetic remanence of implants used in clinical practice. The aims of this study are to investigate the composition and the presence of magnetic remanence for these two orthopaedic implant materials. These two factors may cause implant instability and heat problems as well as degradation of the images quality if the patients undergo magnetic resonance imaging (MRI) examination. The magnetic hysteresis loop and remanence status of stainless steel and titanium alloy orthopaedic implants were investigated with a vibrating sample magnetometer (VSM). Both samples of stainless steel and titanium alloy had been exposed to external magnetic fields up to 1 T (10000 G) and 1.4 T (14000 G), respectively. The compositions of these two orthopaedic implant materials were studied using a scanning electron microscope with energy dispersive X-ray analysis (SEM-EDX). The results of the study demonstrated that ferrous and nickel compositions in stainless steel alloy orthopaedic implants contributed to the residual magnetism, as shown in the hysteresis loop. The titanium alloy orthopaedic implant sample does not contain any ferromagnetic elements. After exposure to a magnetic field, the stainless steel values of retentivity, coercivity and magnetisation are significantly higher compared to those of the titanium alloy. The stainless steel orthopaedic implant sample demonstrates a typical hysteresis loop that suggests the existence of magnetic remanence. In contrast, the titanium alloy orthopaedic implant sample showed no significant remanence phenomenon. By considering the existence of magnetic remanence in the implant is important as potential effect on the MRI image quality.