Superfícies de titânio modificadas por vidros bioativos e hidróxido de potássio: produção, caracterização das superfícies e avaliação biológica in vitro

Abstract

Despite the consolidated success of dental implants under normal conditions, some biological challenges require a higher reactivity of the implant surface. Osseointegration is a process due to physical, chemical and biological stimuli of complex interrelationships, which can be modified for better performance. Seeking better performance in unfavorable metabolic situations or regions of poor bone quality, the coating of the titanium surface with more bioactive materials is advocated in order to accelerate cell attachment and differentiation, and consequent bone apposition. This in vitro experimental study aimed to synthesize, characterize and test the osseoinduction capacity of new bioactive glass composite materials. For this, titanium discs, grade 4, had the surface treated by blasting with aluminum oxide and double acid attack (HNO3 / HF) (group I - "T"). The treated surfaces of the titanium were coated by the dip-coating controlled immersion process with two new bioactive glass-based materials synthesized by the route solgel at low temperatures (groups III, IV and V - TEOS, TEOS + KOH, BIOV, respectively). Finally, two groups received an immersion of basic KOH solution (groups II and IV - "T + KOH, TEOS + KOH"). The topographic characterization methods were performed by roughness analysis techniques (Sa and RMS) by 3D optical profilometer and scanning electron microscopy (SEM); hydrophilicity analysis by sessile droplet method; and thickness measurement of the coating by the transmission electron microscope (MET). The chemical characterization was performed by MEV + energy dispersive X-ray spectrometer (EDS); MET + EDS; and x-ray excited photoelectron spectroscopy (XPS). In vitro biological analyzes using immortalized pre-osteoblastic calvarial cells from MC3T3 neonates were performed by cell viability assays (MTT - 24 hours and 7 days); mineralization test (alizarin - 21 days); and evaluation of cell morphology by SEM and EDS images (7 and 14 days). The effect of the factors under study, surface roughness and hydrophilicity was verified by ANOVA and Tukey post-hoc test (p≤0.05). There was no statistically significant difference between the groups in the evaluation of arithmetic roughness (Sa) and mean square roughness (RMS). The results of the surface hydrophilicity tests showed greater wettability for the bioactive glass surface of the BIOV group (P <0.05). The 24-hour and 7-day MTT assay did not show statistically significant differences between the groups. The TEOS + KOH and BIOV groups obtained the best results for the mineralization assay after 21 days of cell culture. It is concluded that the surfaces tested were viable and non-cytotoxic for growth of MC3T3 osteoblastic cells. The four groups tested, T + KOH, TEOS, TEOS + KOH and BIOV presented positive biological responses of mineralization, growth and cell multiplication. Bioactive glass coatings, regardless of the synthetic pathway, showed significantly better results than uncoated titanium surfaces of bioactive glass.