Calcium and phosphorus are essential for skeletal mineralization and perform a wide array of other biological functions. Calcium is a prime intracellular signalling molecule. It is also involved in muscle contractions (including the myocardium), digestion and blood coagulation. (Theobald 2005) Phosphorus is an intrinsic constituent of many organic substances such as nucleotides, nucleosides, phosphoamino acids and proteins, phospholipids, phosphoglycans and others (Huang, Moe 2011). In addition, it plays a critical role in cellular signalling through phosphorylation of proteins and other substances (Shaikh et al. 2008). The present paper focuses on the role of these two elements in skeletal mineralization, and their use in treatment and medicine. First, it briefly discusses the calcium and phosphorus homeostasis, which occurs in three major organs: kidneys, intestines and bones, and involves an integrated hormonal system which maintains their normal serum levels. Moreover, disorders relevant to their abnormally high levels, hypercalcaemia and hyperphosphataemia, and excessively low levels, hypocalcaemia and hypophosphataemia, are described. Additionally, the physiology and pathology of bone as a prime store of both calcium and phosphorus are presented. Adequate intakes of these nutrients are essential for achieving the peak bone mass (PBM). A negative balance results from age-related bone loss, hence possible osteoporosis. This skeletal disorder is characterized by compromised bone strength, thus predisposing to an increased risk of fractures. One of the pharmacological interventions used in the treatment of osteoporosis is the administration of bisphosphonates. They inhibit the action of osteoclasts, prevent further bone losses and improve it strength (Ferrone, Geraci 2007). In the final part of the article, calcium phosphate based-ceramics, such as coralline hydroxyapatite, calcium hydroxyapatite (HAp), tri-calcium phosphate (TCP), bioglass, calcium phosphate cements (CPC) and their clinical applications are described.

18.3.2013