Development of a Bioactive Titanium Surface via Alkalinization and Naringenin Coating for Peri-Implant Repair: In Vitro Study

This study assessed the effects of titanium (Ti) surface modification with sodium hydroxide (NaOH) associated or not with Naringenin (NA) citrus flavonoid-coating on osteoblastic-like cells (Ob) metabolism. Ti discs were submitted to alkalinization by NaOH solution (5 M, 60 °C) for 24 h; then, the discs were impregnated or not with 100 µg/mL of NA and dried for 1 h at room temperature. The chemical composition, surface topography, and NA release were evaluated. For the biological assays, the discs were placed on 24-well cell culture plates and Ob (Saos-2; ATCC HTB-85) was seeded onto the discs. After different periods, cell adhesion and viability, alkaline phosphatase activity (ALP), and mineralized nodules deposition (MND) were assessed. In addition, cells stimulated with tumor necrosis factor-alpha (TNF-α) were submitted to matrix metalloproteinase (MMP)-2 synthesis and ALP gene expression assessment. Since data presented normal distribution and homogeneity (Shapiro-Wilk; Levene), Student’s t-test or one-way ANOVA/post-hoc tests were selected for data analysis (α = 0.05). Higher roughness was observed on Ti discs submitted to NaOH treatment, while the chemical and NA release evaluations indicated the successful adsorption of NA to alkali-treated Ti surface. Higher cell adhesion, cell viability (after 7 days of culture), ALP activity, and MND were observed on Ti NaOH coated with NA compared to the control group (Ti NaOH) (p < 0.05). Moreover, NA coating also promoted decreased MMP-2 synthesis and increased ALP gene expression in the presence of the inflammatory stimulus TNF-α (p < 0.05). The modification of Ti disks with NaOH associated with NA-coating enhanced bone cell metabolism, suggesting that this type of surface modification has a promising potential to accelerate bone repair and formation around dental implants.