The Evaluation of Biocompatibility, Elemental Composition and Surface Analysis of Retrieved Infra-zygomatic Screws

Abstract

The study aimed to assess the alterations in the morphology, elemental composition, and biocompatibility of infra-zygomatic crest (IZC) miniscrews, before and after their insertion in the patient’s oral cavity. The study was conducted on 16 IZC miniscrews (8 as-received and 8 retrieved). Scanning electron microscopy (SEM) was used to evaluate the miniscrew surfaces. Micrographs were obtained at ×50, ×100, and ×500 magnification. The miniscrews were subjected to Energy-dispersive x-ray (EDX) analysis to investigate the elemental composition. It was performed at four zones of each miniscrew- head, neck, body, tip. Corrosion of the miniscrews was analyzed through the potentiodynamic polarization (PDP) test by immersing the stainless steel (SS) miniscrews in an artificial saliva medium (pH 5.8) and then allowing it to obtain a steady-state open-circuit potential (OCP) for 15 min. Gingival fibroblasts were cultured using gingival tissue which was used to check the biocompatibility of the miniscrews by observing their proliferation and viability by MTT colorimetric assay. The SEM analysis showed generalized surface dullness, variable corrosion, craters, and blunting in the retrieved miniscrews. EDX analyses showed the deposition of additional elements: carbon, oxygen, calcium, and nitrogen in the retrieved miniscrews. PDP tests showed a higher corrosion rate in the retrieved miniscrews, but the results were not significant. The MTT assay showed that the cell viability was higher in the as-received group and the results were statistically significant with a p value of 0.002. It was concluded that the retrieved miniscrews exhibited morphologic surface changes in the form of dullness, blunting of threads and tips, corrosion, craters, and cracks which were not seen in the as-received miniscrews. A higher percentage of adsorbed elements were seen on the retrieved miniscrew surface. The corrosion rate assessed through the PDP test for both groups was comparable. The fibroblast cell viability was significantly reduced in the retrieved miniscrews when compared to as-received miniscrews.

Assessment of the Biological Safety of Metal Alloys TNT (Ti21Nb6Ta) and ВТ-6 (Ti-6Al-4V)

“…Surgical implants are usually made from metallic materials, including austenitic stainless steel, cobaltchromium alloys, as well as titanium and its alloys [15]. In the 1940s, titanium began to be used as a material for medical implants due to its favorable properties, including low density, exceptional mechanical characteristics, and lack of toxicity [16]. It is known that metal ions can be released from metallic materials due to corrosion.…”