Avaliação in vitro e in vivo de superfícies de titânio revestidas com vidro bioativo

Abstract

Objectives: This experimental in vitro and in vivo study tested theosteoinduction ability of a new nanostructured titanium surface coated with bioglass with calcium phosphate. Methods: Surface roughness wasevaluated by atomic force microscopy using 9 specimens of three groups: sandblasting and acid etching commercially pure titanium (cpTi) and bioglass coated dried at temperatures of 370C (BGTi37) or 6000C (BGTi600). Rat calvarial osteogenic cells were cultured in supplemented -MEM medium in contact or not (control) with sandblasting and acid etching (SLA) commercially pure titanium discs (cpTi) and bioglass coated (BGTi37 and BGTi600). Cell viability and alkaline phosphatase (ALP) activity were measured after 7 days of culture. The mineralization was assessed after 14 days of culture. The data were compared by analysis of variance (ANOVA) complemented by Tukey test. The level of significance was 5%. Scanning electron microscopy after 7 and 14 days assessed osteoblasts morphology in contact with the three surfaces. Fourteen SLA commercially pure titanium screws (cpTi -control) andfourteen experimental screws bioglass coated dried at temperatures of 370C (BGTi37) were randomly placed into 14 male Wistar rats tibiae. The animals were sacrificed after 14 and 28 days and their tibias processed for micro-CT analysis. Results: The cpTi group (129.6 nm) showed the highest average roughness, followed by BGTi600 group (91.85 nm), which were statistically similar. The BGTi37 group (74.51 nm) showed the lowest surface roughness compared to the other two groups. Cell viability, ALP activity and mineralization of BGTi600 group were significantly lower than the control and cpTi groups. BGTi37, cpTi and control groups showed no significant differences in cell viability, ALP activity and mineralization. The number of cells in contact with all surfaces was higher in 14 days compared to 7 days. Higher amount of osteoblasts was observed in contact with the cpTi surface and the smaller amount in contact with the BGTi600 surface. Osteoblasts in contact to cpTi surface showed a flat polygonal shape and were larger than the BGTi37 and BGTi600 groups, which presented with a sharper morphology, most notably in the BGTi600 group. The number of cytoplasmic processes, intercellular junctions and vesicles observed in specimens of BGTi600 group was markedly lower than in cpTi and BGTi37 groups. The micro-CT parameters of the cortical and trabecular bone around the experimental (BGTi37) and controls (Ticp) screws presented no statistical differences. Conclusions: The BGTi37 surface showed biological behavior similar to a SLA titanium surface (cpTi), with excellent long-term results already established in the literature. A very promising fact, considering the improvement possibilities of this experimental surface in future studies.