Nowadays, life expectancy is two times higher than in the beginning of the 20th century, therefore, the human body is subjected to higher cumulative stress that results in degradation of the tissues and so new therapies are required to overcome these problems. Thus, a new biomaterial was developed, a modified apatite with silicon, as it is well known silicon plays an important role on several metabolic pathways. Hence, this book describes the "in vitro" characterization of Silicon-Hydroxyapatite developed to enhance bone regeneration. The studies described in this book show the role of Silicon-Hydroxyapatite on several physical, chemical and biological processes. The results indicate that the enhanced bioactivity of Silicon-Hydroxyapatite is a combination of acellular and cellular mechanisms. The more negative surface and higher dissolution rate decreases the time required for the formation of an apatite layer, which is considered to be an important factor for osseointegration. And also the enhanced proliferation and differentiation of bone cells (human osteoblast and osteoclast) induced by the presence of Silicon-Hydroxyapatite can lead to faster bone regeneration.