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3D Printing Technologies in Metallic Implants

Figure 15. Schematic presentation of the dual modulation procedure (Adapted from Ref [117] with permission from The Royal Society of
Chemistry).

resulted in early bone tissue integration and proper tissue The production of 3D printed titanium porous
ingrowth. Furthermore, a good bonding in the interfacial structure is progressing toward the commercial stage; for
regions between the bone tissue and the implant surface instance, U.S. Food and Drug Administration (FDA) has
was observed. Moreover, it enhanced new bone formation approved the 3D printed titanium implants, which are
and accelerated mineralization were seen in the periphery known as Emerging Implant Technologies (EIT) Cellular
of the implant material. Overall, porous materials have Titanium (Figure 17) produced by a German medical
®
better biological performance than the dense type. device manufacturer, for spinal applications. This new
Furthermore, CaP plays a crucial role in early bone tissue product was designed based on the ideal pore shape and
integration with the implant. Figure 16 shows a brief size, with the goal to achieve improved cell proliferation
explanation about doping and coating procedure. and bone ingrowth conditions. In fact, the EIT cervical
Among the titanium-based biomaterials, Ti6Al4V is cage’s anatomical architecture can potentially overcome
known for its improved mechanical properties relative to the surgical and biomechanical issues related to the cervical
the pure Ti. Unfortunately, the toxic effects of Al and V multi-level fusion by modifying the vertebral endplate
restrict its application in clinical settings. Nevertheless, contact and sagittal balance restoration [126] . Another
since the release of Al and V is in low amounts, Ti6Al4V example approved by FDA is the MATRIXX stand-alone
®
can still be used in medical devices and implants. Many cervical system for patients suffering from degenerative
studies have been performed to examine the design disc treatment will be assisted by it. Furthermore, a number
parameters, such as porosity and pore size, in relation of companies that utilize direct metal printing technology,
to this subject. Table 2 presents a brief review of these such as IMR, nuVasive, and Stryker, are working on
studies. production AM manufactured titanium implants [127] .

34 International Journal of Bioprinting (2021)–Volume 7, Issue 7