A comprehensive review on metallic implant biomaterials and their subtractive manufacturing

Abstract

There is a tremendous increase in the demand for converting biomaterials into high-quality industrially manufactured human body parts, also known as medical implants. Drug delivery systems, bone plates, screws, cranial, and dental devices are the popular examples of these implants - the potential alternatives for human life survival. However, the processing techniques of an engineered implant largely determine its preciseness, surface characteristics, and interactive ability with the adjacent tissue(s) in a particular biological environment. Moreover, the high cost-effective manufacturing of an implant under tight tolerances remains a challenge. In this regard, several subtractive or additive manufacturing techniques are employed to manufacture patient-specific implants, depending primarily on the required biocompatibility, bioactivity, surface integrity, and fatigue strength. The present paper reviews numerous non-degradable and degradable metallic implant biomaterials such as stainless steel (SS), titanium (Ti)-based, cobalt (Co)-based, nickel-titanium (NiTi), and magnesium (Mg)-based alloys, followed by their processing via traditional turning, drilling, and milling including the high-speed multi-axis CNC machining, and non-traditional abrasive water jet machining (AWJM), laser beam machining (LBM), ultrasonic machining (USM), and electric discharge machining (EDM) types of subtractive manufacturing techniques. However, the review further funnels down its primary focus on Mg, NiTi, and Ti-based alloys on the basis of the increasing trend of their implant applications in the last decade due to some of their outstanding properties. In the recent years, the incorporation of cryogenic coolant-assisted traditional subtraction of biomaterials has gained researchers’ attention due to its sustainability, environment-friendly nature, performance, and superior biocompatible and functional outcomes fitting for medical applications. However, some of the latest studies reported that the medical implant manufacturing requirements could be more remarkably met using the non-traditional subtractive manufacturing approaches. Altogether, cryogenic machining among the traditional routes and EDM among the non-traditional means along with their variants, were identified as some of the most effective subtractive manufacturing techniques for achieving the dimensionally accurate and biocompatible metallic medical implants with significantly modified surfaces.

Immune Profiling and Multiplexed Label‐Free Detection of 2D MXenes by Mass Cytometry and High‐Dimensional Imaging

“…In particular, Ti-, Nb-, Mo-, and Ta-based MXenes selected in this study, are all composed by biocompatible transition metals used in medical settings as metal alloy implants, contrast agents, and biomaterial surface coatings. [44] This positive behavior in biological systems has already been reported for other inorganic nanoparticles and nanostructured materials precisely formulated for various drug delivery and imaging applications. [45]…”

Bio-high entropy alloys: Progress, challenges, and opportunities

“…As a new bio-alloy material, Bio-HEAs require a series of biosafety assessments before they can be implanted in organisms, and the common factors affecting the biology of biomedical implants are shown in Figure 13 . For Bio-HEA to be truly used in the clinical field as a biomedical implant, its biocompatibility needs to be experimentally proven by the mechanical, physical, and degradation properties, by sterilization (freeing the implant surface from all types of microorganisms), by toxicological aspects (examination and treatment of any toxins or toxic substances), by surgery, implant site and load-bearing capacity ( Davis et al, 2022 ). Based on the existing research work, this chapter summarizes the biocompatibility performance of Bio-HEAs in terms of their cytocompatibility and corrosion resistance in physiological solutions.…”

Decellularized Wharton Jelly Implants Do Not Trigger Collagen and Cartilaginous Tissue Production in Tracheal Injury in Rabbits

“…Another possibility is that this biomaterial needs to be modified to have a more satisfactory response within the organism. This modification process is common in metallic implants when, for example, ions are added in the manufacturing process [ 28 ]. However, these results can be extrapolated to this structure, in which the addition of growth factors or even undifferentiated cells together with this framework can stimulate migration, the proliferation of cells, and consequently tissue regeneration.…”