This document discusses vitamin D, calcium, and phosphate metabolism. It covers the roles and regulation of vitamin D, calcium, and phosphate in the body. Vitamin D helps regulate calcium and phosphate levels and is required for bone mineralization. Deficiencies can lead to conditions like rickets, osteomalacia, and osteoporosis. The document also discusses oral implications of these nutritional deficiencies and metabolic bone diseases. Maintaining proper levels of vitamin D, calcium, and phosphate is important for overall health and bone health.