Enhancing Titanium Osteoconductivity by Alkali-Hot Water Treatment

Titanium and its alloys are essential in orthopedic and dental treatments owing to their high strength, corrosion resistance, and superior biocompatibility compared with those of other metals. However, titanium alloys are bioinert. Previous studies have indicated that alkali treatment (AT) is a straightforward method to create a surface oxidization layer on titanium, thereby improving its bioactivity. Herein, alkali-hot water pretreatment was used to enhance the osteoconductivity of titanium and to identify a simple and efficient means of enhancing the interaction between osteoblasts and implants for clinical applications. Commercial pure titanium plates were ground (CP Ti) and subjected to alkali solution and hot water treatments (AWT). Single-process CP Ti specimens were prepared via either AT or hot water treatment (WT). Network-like structural features were observed in the AT specimens and were further refined and densified in the AWT specimens. Water contact angle testing revealed that the hydrophilicity of the titanium specimen (80° for CP Ti) increased by 19° for the AT specimens but decreased by 59° for the AWT specimens. Mouse preosteoblasts (MC3T3-E1 cells) were used for <i>in vitro</i> evaluation. After 24 h of culturing, the number of attached MC3T3-E1 cells on the AWT specimens was 1.5 times larger than that on the CP Ti specimens, suggesting that the alkali-hot water treatment enhanced the initial cell attachment. Cell proliferation evaluation indicated that fewer cells were detected in the AT and AWT specimens compared with those in the CP Ti or WT specimens. However, osteogenic differentiation evaluation on day 10 revealed a 1.5-fold higher alkaline phosphatase expression in cells cultured on the AWT specimens than in cells cultured on the CP Ti specimens. These findings demonstrate the good cytocompatibility and osteoconductivity of AWT Ti, highlighting its benefits in orthopedics and dental treatments.