Titanium dental implants have common clinical applications due to their biocompatibility, biophysical and biochemical characteristics. Although current titanium is thought to be safe and beneficial for patients, there are several indications that it may release toxic metal ions or metal nanoparticles from its alloys into the surrounding environment, which could lead to clinically relevant complications including toxic reactions as well as immune dysfunctions. Hence, an adequate selection and testing of medical biomaterial with outstanding properties are warranted. This study was designed to explore the biocompatibility of smooth titanium-niobium alloy (S_TiNb) versus smooth titanium commercially pure (S_TiCp)—a reference in implantology. All experiments were performed in vitro using human osteoblast-like SaOs-2 and monocyte THP-1 cell lines as models. Cell adhesion and growth morphology were determined by scanning electron microscopy, while cell viability was evaluated using WST-1 assay. Because niobate anions or niobium nanoparticles can be released from implants during biomaterial-cell interaction, potential immunotoxicity of potassium niobate (KNbO₃₎ salt was evaluated by examining both metabolic activity and transcriptomic profiling of treated THP-1 monocytes. The main findings of this study are that S_TiCp and S_TiNb discs do not show an impact on the proliferation and viability of SaOs-2 cells compared to polystyrene surfaces, whereas a significant decrease in THP-1 cells’ viability and metabolic activity was observed in the presence of S_TiNb discs compared to the control group. However, no significant changes were found neither at the metabolic activity nor at the transcriptomic level of THP-1 monocytes exposed to KNbO₃ salt, suggesting that niobium has no effect on the immune system. Overall, these data imply a possible toxicity of S_TiNb discs toward THP-1 cells, which may not be directly related to niobium but perhaps to the manufacturing process of titanium-niobium alloy. Thus, this limitation must be overcome to make titanium alloy an excellent material for medical applications.

The osseointegration of implants is defined as the direct anatomical and functional connection between neoformed living bone and the surface of a supporting implant. The biological compatibility of implants depends on various parameters, such as the nature of the material, chemical composition, surface topography, chemistry and loading, surface treatment, and physical and mechanical properties. In this context, the objective of this study is to evaluate the biocompatibility of rough (Ra = 1 µm) and smooth (Ra = 0 µm) surface conditions of yttria–zirconia (Y-TZP) discs compared to pure zirconia (ZrO₂) discs by combining a classical toxicological test, morphological observations by SEM, and a transcriptomic analysis on an in vitro model of human Saos-2 bone cells. Similar cell proliferation rates were observed between ZrO₂ and Y-TZP discs and control cells, regardless of the surface topography, at up to 96 h of exposure. Dense cell matting was similarly observed on the surfaces of both materials. Interestingly, only 110 transcripts were differentially expressed across the human transcriptome, consistent with the excellent biocompatibility of Y-TZP reported in the literature. These deregulated transcripts are mainly involved in two pathways, the first being related to “mineral uptake” and the second being the “immune response”. These observations suggest that Y-TZP is an interesting candidate for application in implantology.

Modern dental implantology is based on a set of more or less related first-order parameters, such as the implant surface and the intrinsic composition of the material. For decades, implant manufacturers have focused on the research and development of the ideal material combined with an optimal surface finish to ensure the success and durability of their product. However, brands do not always communicate transparently about the nature of the products they market. Thus, this study aims to compare the surface finishes and intrinsic composition of three zirconia implants from three major brands. To do so, cross-sections of the apical part of the implants to be analyzed were made with a micro-cutting machine. Samples of each implant of a 4 to 6 mm thickness were obtained. Each was analyzed by a tactile profilometer and scanning electron microscope (SEM). Compositional measurements were performed by X-ray energy-dispersive spectroscopy (EDS). The findings revealed a significant use of aluminum as a chemical substitute by manufacturers. In addition, some manufacturers do not mention the presence of this element in their implants. However, by addressing these issues and striving to improve transparency and safety standards, manufacturers have the opportunity to provide even more reliable products to patients.

Innovation in oral implantology is constantly on the move, with a constant search for new biomaterials to overcome many of the limitations of the biomaterials used in current implantable medical devices. This study explores the biocompatibility of an innovative 5% calcium-to-zirconia (Ca-SZ) coating deposited by PVD on TA6V substrates for use in oral implantology. In order to determine the contribution of the Ca-SZ coating, an in vitro biocompatibility study was carried out to assess the potential influence of the Ca-SZ coating (1) on the viability and proliferation of saos-2 and HaCaT cells over a short-term exposure period of 96 h, (2) on the synthesis of pro-inflammatory cytokines, and (3) on the synthesis of osteogenic differentiation markers over a long-term exposure period of 21 days, in comparison with reference biomaterials. The sampling consisted of n = 3 biological replicates, and a p-value of <0.05 was used as the threshold for statistical significance. Viability and proliferation kinetics to WST-1 and CyQUANT NF, respectively, showed improved viability/proliferation of Ca-SZ exposed to both cell lines independently. The TNF-alpha and IL-6 assays revealed reduced levels of cytokines compared with the reference biomaterials, including the control groups. In parallel, in Saos-2 cells exposed to Ca-SZ for 21 days under osteogenic conditions increased expression of osteogenic markers, such as the synthesis of soluble collagens, alkaline phosphatase (ALP), osteopontin, and osteocalcin, reflecting dynamic and facilitated osteoblastic differentiation, which was supported by the formation of hydroxyapatite (HA) crystals observed by SEM micrograph and confirmed by EDS mapping. In conclusion, Ca-SZ demonstrates an overall better biocompatibility compared with reference biomaterials, linked to a bioactive interaction of calcium, promoting cell proliferation and differentiation for optimal osteointegration, underlining its potential as a relevant innovation for next-generation implants.

Oral implantology faces a multitude of technical challenges in light of current clinical experience, underlining the need for innovation in implantable medical devices in both mechanical and biological terms. Objectives: This study explores the influence of the thickness factor of calcium-doped zirconia (Ca-SZ) coatings deposited by PVD on their intrinsic mechanical properties and the determinism of the latter on adhesion to the TA6V alloy substrate after mechanical loading for applications in dental implantology. Methods: Three separate thicknesses of 250 nm, 450 nm and 850 nm were evaluated in terms of mechanical strength, modulus of elasticity and adhesion to the substrate, in accordance with ISO 20502:2005. Results: The results show an increase in apparent modulus of elasticity with thickness, reaching values of around 25.05 GPa and 36.3 GPa, close to the cortical bone for the 250 nm and 450 nm thick coatings, respectively. Adhesion tests show a progressive improvement up to 450 nm, followed by a similar observation at 850 nm, underlining the importance of optimal thickness to balance mechanical protection and biomechanical compatibility. Furthermore, the initial roughness and topography of the substrate were not influenced by the different thicknesses of the Ca-SZ coating. Conclusions: Together, these results reinforce the potential of Ca-SZ coatings to minimise stress shielding in dental implants.

The design of new, biomimetic biomaterials is of great strategic interest and is converging for many applications, including in implantology. This study explores a novel approach to improving dental implants. Although endosseous TA6V alloy dental implants are widely used in oral implantology, this material presents significant challenges, notably the prevalence of peri-implantitis. Therefore, in this study, we investigate a new advance in the design of hybrid medical devices. This involves the design of a Ca-SZ coating deposited by PVD on a TA6V substrate. This approach aims to overcome the inherent limitations of each of these materials, namely TA6V’s susceptibility to peri-implantitis on the one hand and zirconia’s excessively high Young’s modulus compared with bone on the other, while benefiting from their respective advantages, such as the ductility of TA6V and the excellent biocompatibility of zirconia, offering relevant prospects for the design of high-performance implantable medical devices. This study integrates characterisation techniques, focusing on the structural and elemental analysis of the Ca-SZ coating by XRD and TEM. The results suggest that this coating combines a tetragonal structure, a uniform morphology with no apparent defects, a clean interface highlighting good adhesion, and a homogeneous composition of calcium, predisposing it to optimal biocompatibility. All of these findings make this innovative coating a particularly suitable candidate for application in dental implantology.