Lately clinical evidence has suggested that the development of osteonecrosis of the jaws (ONJ) might be associated to assumption of high doses of nitrogen-bisphosphonate (N-BPs), quite common in the treatment of multiple myeloma and skeletal metastasis due to breast and prostate cancer. Bisphosphonates are used for the treatment of several pathologies such as osteoporosis, Paget's disease, multiple myeloma, malignant hypercalcemia, breast and prostate tumours, and other tumours associated with bone metastasis. Their use might improve patient's life standard, reducing pain and complications of the skeletal structure. In this report three clinical cases of ONJ of patients in treatment with BPs are presented, and the possible pathogenesis is analysed. Further-more, treatment guidelines for the management of patients in treatment with BPs who need restorative dental care and oral surgery are proposed.