**6. Future trends**

It is hard to say which is the most feasible bioglass. So the focus of the research is now on optimisation of the materials with deposition techniques, influenced by the parameters of the coatings and the composition of the bioglass, in order to obtain a multi-functional coatings, that will give long-term qualitative implants without side effects and ensuring regeneration.

**Figure 7** shows the challenges and future trends for bioactive glasses (BGs)in medicine promoted by researchers which will lead to better implants. The properties of a biomaterial are decisive in ensuring the biocompatibility of an implant:


• another important aspect is related to the machinability of the biomaterial, this influencing the engineering of the implant itself.

Reliable Coatings with BGs on the mettalic implants are the oldest challenge but still researched. Thanks to their excellent mechanical properties and corrosion resistance, some metals are used as passive substitutes for the replacement of hard tissues (total hip and knee implants), as well as fracture implants (plates and rods), column fixing devices, and implantology. Dental. Other metal alloys have more active roles in implantology, such as vascular stents, catheter guidewires, orthodontic wires, and cochlear implants.

However, the biocompatibility of metal implants creates considerable concerns due to the fact that they can corrode in an in vivo environment [6]. Weakening of the implant by disintegrating its actual material, respectively the harmful effects of the resulting chemical compounds on neighboring tissues and organs are among the consequences of corrosion.

Pure metals are less commonly used, their alloys being used more often due to the fact that they improve some of their properties, such as corrosion resistance and hardness. Three groups of materials dominate the group of metallic biomaterials: 316 L stainless steels, cobalt and pure titanium alloys or titanium alloys.

Every material and class of materials works differently after the implantation, like some metals encapsulate fibrous tissue. The great advantage of the coatings on bioglass is that is not releasing toxic ions in the human body due to the potential to improve the implant stability by bonding it to the host bone and protect the implant from corrosion resistance.

The technologies involved for the surface modification of metallic implants with bioglass are: thermal spraying, sol–gel, chemical and electrochemical treatment. Unfortunately, not all technologies are suitable, some of them show many disadvantages like poor bonding strength between implants and coatings, the induction of phase transformation, modifications in the properties of coating or metallic implant, or both, and presence of impurities. **Table 6** present a synthesis of different glass coatings obtained through various methods [57].

Another perspective and future tendince of biomaterials is nanomedicine. Nanomedicine can be defined as an application of nanotechnology in the field of health in order to maintain and / or improve the health of the population using knowledge about the human body at the molecular level, as well as tools / nanoscale structures [22].

For this purpose, physical, chemical and biological properties of nanoscale materials are exploited, often new or improved properties, and the resulting nanostructures (nanoparticles or nanodevices), having the same size as biological entities, can interact more rapidly at the biomolecular level. on the surface as well as inside the cell [22].

So, in the near future, nanomedicine will seek to provide the tools and devices for research and practice, useful in the medical clinic, which could revolutionize the current way of thinking (prevention and diagnosis) and action (applied therapies) in the medical field.

By using nanoengineering, artificial tissues can be obtained and used to replace affected organs (kidneys, liver) or to regenerate nerves or produce implants that restore lost senses, such as sight or hearing. A major contribution is expected to nanomedicine could be brought about in areas such as: the definition and classification of diseases, their diagnosis and treatment, and the improvement of the structure and functioning of the human body [22].



#### **Table 6.**

*Summary of bioactive glass coatings on different metallic substrate.*

In recent years, nanotechnology has found countless applications in the medical field, in the fields of: pharmaceutical (in targeted drug therapy), regenerative medicine (making nano-robots and devices used in cell regeneration), disease prevention, diagnosis (including by methods high-performance imaging) and nano-technology-based therapy.

The future of the field stays in the nanotechnology, being the most effective on cell and tissue level, mainly on the integration and regeneration, but also the identification of effective ways to trigger and control the regenerative process. The "nanobiomimetic" strategy depends on the following elements: intelligent biomaterials, bioactive signaling molecules and cells. Biomaterials are designed to react positively to changes in the proximity environment, stimulating specific regenerative events at the molecular level, directing cell proliferation and then differentiation, as well as the production and organization of the extracellular matrix.

A huge impact will also have the ability to implant cells, intelligent bioactive materials, which trigger the process of self-healing through the patient's own stem cells [22].

The field of nanotechnologies has established itself in recent years as one of the most topical fields, with a sustained pace of development and application and a revolutionary impact on industry and society. The global emergence of government investment programs in the field of nanotechnology is clear evidence of global interest in this field.

The potential evolutions of the research - development in the field of nanotechnologies, in the following years, are the following:

