Osseointegration properties of titanium implants with different pore diameters: experimental study

Abstract

Introduction. Additive technologies make it possible to create implants to replace bone defects. Determining the optimal parameters of a porous structure remains an urgent issue. The experimental research aimed to study the biocompatibility of implants made of titanium alloy with different pore diameters. Materials and methods. The study was carried out in two stages. The first stage included an in vitro study carried out on test cultures of diploid human fibroblasts to assess the cytotoxicity of the titanium alloy, from which samples were made for the second stage in vivo. The in vivo study was performed on three groups of rabbits (n=18), which received samples of the developed implants. The average age of subjects was 7±1 months, the weight being 4.675±258 g. All samples were 4 mm in diameter and 6 mm high. In group 1, the pore size was 100 μm; in group 2 – 200 μm; and in group 3 – 400 μm; the porosity was 55%, 62%, and 70%, respectively. The animals were sacrificed on day 90 after placement of the samples. Histological, morphological, and electron microscopic studies were performed to assess the osseointegrative properties of the implants. Results. In the in vitro study, we detected no toxic effects of the material on the test culture. In the in vivo study, the histological analysis did not reveal inflammation in peri-implant tissues in any of the groups. The morphological study showed a newly formed tissue in the area of the formed defect which consisted of young bone trabeculae with osteoblasts located on their surface. In group 3, we found the greatest prevalence of mature bone trabeculae. The samples with a 400-μm pore diameter revealed the largest area of filling the implant with newly formed bone tissue. Conclusion. Samples with a pore diameter of 400 μm have the highest osteointegrative properties. Keywords: osteointegration, biocompatibility, titanium implants, additive technologies, 3D-printing