Bisphosphonates are generally administered either orally or intravenously. Orally administered bisphosphonates are primarilly used in the treatment of postmenopausal osteoporosis, glucocorticoid-induced osteoporosis, and Paget's disease. When orally administered, only about 1% is absorbed from the tractus from the tractus digestivus. With intravenous administration, higher blood levels levels are reached. Intravenously administered bisphosphonates are used in the treatment of hypercalcaemia, Kahler's disease, and bone metastases of other malignancies. A few cases of osteonecrosis of the jaw(s) are seen especially when more powerful bisphosphonates are administered intravenously. This osteonecrosis is most often provoked by means of an invasive oral treatment. Bisphosphonate-associated osteonecrosis is very difficult to treat. Therefore, dental preventive measures and treatment of dental foci and other inflammations are recommended before starting bisphosphonate therapy.