Biological Properties of White Portland Cement and the Effects of Nano-Silica on Its Mechanical Strength for Bone Substitute Applications

Abstract

White Portland Cement (WPC) is a ceramic material primarily composed of tricalcium silicate and dicalcium silicate, with a ferric oxide content of less than 0.5%. This composition makes it suitable for medical applications, particularly in orthopedic and dental surgery. This study focuses on developing composite material by incorporating nano-silica into WPC to enhance its mechanical and biological properties. The primary objective is to evaluate the biocompatibility and mechanical performance of the material through in vitro testing, including immersion in simulated body fluid (SBF) and cytotoxicity assessment on osteoblast cells. The results indicate that WPC exhibits both osteoinductive and osteoconductive properties, as evidenced by hydroxyapatite formation on its surface after 28 days of immersion in SBF. Cytotoxicity testing revealed that higher material concentrations reduced cell viability due to the release of calcium hydroxide (Ca(OH)₂), which may increase alkalinity beyond biocompatible levels. Regarding mechanical properties, the addition of nano-silica at 1%, 2%, and 3% significantly enhanced the material’s compressive strength. The highest compressive strength, 58.12 MPa, was observed at a 3% nano-silica concentration, attributed to structural reinforcement, reduced porosity, and increased formation of calcium silicate hydrate (C-S-H) gel, a key component in improving mechanical strength. These findings demonstrate that the development of a WPC-nano-silica composite enhances both mechanical and biological properties, highlighting its potential as a bone substitute material for medical applications.