Surface modification aspects of resin-based and titanium biomedical implants

Abstract

Biomaterials are materials that have the ability to elicit appropriate host responses in specific applications. However, a material that demonstrates certain biocompatibility may not be a biomaterial. In fact, biocompatibility can be classified into surface biocompatibility and structural biocompatibility. Surface biocompatibility relates to the suitability of the chemical, biological, and physical properties at the surface. On the other hand, structural biocompatibility entails the optimal adaptation of the mechanical behavior of the host tissue, such as elastic modulus and strength. The ideal interaction between biomaterials and host tissues occurs when both surface and structural biocompatibility are achieved.

Implants, being as one of the biomaterials with increasing global utilization, continue to be of interest to researchers whom to develop new technologies for enhancing clinical performance by changing existing treatment modalities and devices. Aside from exploring new materials, efforts are being made to enhance the surface properties of existing materials so that the functionality of implants can be enhanced, i.e., improving their osseointegration and physical properties. In situations requiring bone substitutes, there is a search for advancements in synthetic graft materials. Thus, the purpose of this study was to investigate both the surface and structural compatibilities of polymeric composite and titanium implant materials.

This project comprises multiple dimensions of implants. Firstly, a polymeric resin-based HA-composite containing bioactive glass and nano-hydroxyapatite was developed. The novel HA-composite material exhibited superior collapse strength, compression modulus, and excellent degree of conversion, whereas the hydrophilicity was enhanced through cold atmospheric plasma treatment. In addition, the HA-composite was capable of being utilized in any dental resin composite system and amenable to 3D printing, offering cost-effectiveness and the ability to mimic the internal porous cancellous bone structure, while still keeping excellent biocompatibility and osteogenic characteristics. Further, an animal trial was done and proved the HA-composite could promote osteogenesis, highlighting its surface biocompatibility and osteogenic capacity.

On the other hand, the surface compatibility of titanium implants is topography-patterned with hybrid nano/microstructures. The interaction between the topography and fluid shear stress in MC3T3-E1 cells was verified using a custom-made microfluidic device, whereas cellular proliferation was found to be influenced by both the surface topography and fluid shear stress. The animal model was used to explore how osteogenesis on different implant surfaces was affected by fluid and peri-implantitis.

Ultimately, this research study concluded the interaction effects of surface and structural compatibility for both polymeric and titanium implants at various scales from laboratory, in vitro and in vivo studies. Specifically, polymer-based HA-composite implants, together with the application of plasma, exhibited impressive osteogenic properties, demonstrating a high potential as a novel biomaterial in the future. Moreover, the topography of the titanium implant surface of the material interacted with fluid shear stress to alter cellular response.