This report provides important background information on osteoporosis (OP) and bone complications of cancer for the dental team, and discusses why bisphosphonate (BP) therapy is vital for patients with the two conditions. It also addresses several questions, including in particular: 'Is withholding BP therapy the best way to prevent osteonecrosis of the jaw (ONJ) occurrence?' Also,'Of the two, which is more important: ONJ or OP fracture prevention?' CPD/Clinical Relevance: BP therapy offers OP patients the promise of a fracture-free life and the prevention of fracture-related pain, disability, loss of qualify of life (QOL) and the shortening of life. Without BP therapy, the lifetime risk of fracture occurrence in OP patients is as high as 1 in 2 women and 1 in 5 men; whilst using it, the relative risk of ONJ occurrence is as low as between 1 in 10, 000 and 1 in 100, 000. To cancer patients with bone complications, it offers the much needed pain relief and improvement in QOL. In cancer patients, the risk of ONJ is almost 100 times higher but, despite that, oncologists advocate BP therapy for virtually all the patients. Therefore, when prescribed, BP therapy merits the whole-hearted support of the dental team.