Ion-substituted calcium phosphate (CP) coatings have been extensively studied as promising materials for biomedical implants due to their ability to enhance biocompatibility, osteoconductivity, and bone formation. This systematic review aims to provide a comprehensive analysis of the current state of the art in ion-doped CP-based coatings for orthopaedic and dental implant applications. Specifically, this review evaluates the effects of ion addition on the physicochemical, mechanical, and biological properties of CP coatings. The review also identifies the contribution and additional effects (in a separate or a synergistic way) of different components used together with ion-doped CP for advanced composite coatings. In the final part, the effects of antibacterial coatings on specific bacteria strains are reported. The present review could be of interest to researchers, clinicians, and industry professionals involved in the development and application of CP coatings for orthopaedic and dental implants.

Magnesium alloys are considered one of the most promising materials for biodegradable trauma implants because they promote bone healing and exhibit adequate mechanical strength during their biodegradation in relation to the bone healing process. Surface modification of biodegradable magnesium alloys is an important research field that is analyzed in many publications as the biodegradation due to the corrosion process and the interface with human tissue is improved. The aim of the current preliminary study is to develop a polymeric-based composite coating on biodegradable magnesium alloys by the solvent evaporation method to reduce the biodegradation rate much more than in the case of simple polymeric coatings by involving some bioactive filler in the form of particles consisting of hydroxyapatite and magnesium. Various techniques such as SEM coupled with EDS, FTIR, and RAMAN spectroscopy, and contact angle were used for the structural and morphological characterization of the coatings. In addition, thermogravimetric analysis (TGA) was used to study the effect of filler particles on polymer thermostability. In vitro cytotoxicity assays were performed on MG-63 cells (human osteosarcomas). The experimental analysis highlights the positive effect of magnesium and hydroxyapatite particles as filler for cellulose acetate when they are used alone from biocompatibility and surface analysis points of view, and it is not recommended to use both types of particles (hydroxyapatite and magnesium) as hybrid filling. In future studies focused on implantation testing, we will use only CA-based composite coatings with one filler on magnesium alloys because these composite coatings have shown better results from the in vitro testing point of view for future potential orthopedic biodegradable implants for trauma.

Trauma orthopaedic surgery was the first domain to use degradable metallic implants made of magnesium alloys since the early 20th century. Unfortunately, the major limitation that consists of rapid degradation and subsequent implant failure, which occur in physiological environments with a pH between 7.4 and 7.6, prevents its widespread application. The biggest challenge in corrosion assay is the choice of the testing medium in order to reproduce more closely in vivo conditions. The current study was focused on two Mg-Zn-Ag alloys (Mg7Zn1Ag and Mg6Zn3Ag) and the Mg1Ca alloy. Dulbecco’s Modified Eagle Medium (DMEM) and Kokubo’s simulated body fluid solution (SBF) were selected as testing mediums and we follow the corrosion evaluation by the corrosion rate and mass loss. Also, the corrosion behaviour was interpreted in correlation with the microstructural features and alloying elements of the experimental magnesium-based alloys revealed by optical microscopy (OM), X-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDX). The experimental results highlight the more corrosive nature of the SBF environment and that a higher percentage of silver (2.5 wt.%) exhibited a better corrosion resistance. We consider that the magnesium alloy Mg6Zn3Ag showed valuable biodegradation characteristics to be considered as raw materials for manufacturing small trauma implants.