Researchers at the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), an autonomous institute of the Department of Science and Technology (DST), have developed a innovative bi-layered single-piece dental implant that integrates titanium alloy (Ti6Al4V) and yttria-stabilized zirconia (YSZ) into a unified structure. This design addresses limitations of traditional three-component dental implants that are susceptible to micromovements at the abutment interface, which can compromise osseointegration and lead to implant loosening, while also requiring two to three surgical procedures that increase patient discomfort and clinical complexity.
The implant was fabricated using Spark Plasma Sintering (SPS), an advanced powder metallurgy technique that utilized a custom-designed tapered graphite die for precise temperature control during sintering. This allowed simultaneous densification of Ti6Al4V and YSZ despite their widely differing sintering temperatures, achieving a material density of 99.5% and producing a strong, defect-free bi-layered structure in a single processing step. The Ti6Al4V serves as the load-bearing fixture for strong jawbone integration, while YSZ forms the crown region to provide superior wear resistance and aesthetics.
Technical analysis confirmed a distinct, well-bonded interface without cracks, delamination, pores, or secondary phases. The structure showed fine YSZ grains of approximately 0.3 µm, while Ti6Al4V grains near the interface were refined to 0.3–1 µm compared to the bulk, with no noticeable elemental diffusion observed across the interface. Mechanical evaluation demonstrated exceptional properties with hardness values up to 1350 HV, compressive strength of approximately 1550 MPa, and flexural strength of approximately 310 MPa, all comparable to or exceeding commercial implant materials.
In vitro biological studies confirmed non-cytotoxic behavior and excellent biocompatibility. MTT assays using L929 mouse fibroblast cells showed metabolic activity exceeding 90% across all tested concentrations, surpassing the minimum threshold for biomaterials. Hemolysis tests indicated negligible red blood cell damage, validating the material's suitability for dental applications. The fabrication approach demonstrates high reproducibility and is suitable for scaling up to industrial production, though machining trials using a 5-axis CNC machine revealed some challenges related to tool movement along curved surfaces, with process optimization currently underway.
This innovation aligns with India's growing demand for affordable, high-performance dental implants and strengthens indigenous biomedical device development. The work has been published in the journal Materials Letters on ScienceDirect with the DOI: https://doi.org/10.1016/j.matlet.2023.134403.