How does low bone mineral density alter treatment decisions? Osteoporosis and osteopenia are major health care issues that may impact on periodontal and implant therapy. Because of the prevalence of osteoporosis, understanding its etiology and the current treatment regimens for patients with low bone mineral density is essential for dental professionals. Millions of patients are now taking medications for the treatment of osteoporosis, and periodontists should be aware of the many medication options that are prescribed. The most frequently prescribed drugs are the bisphosphonates. It is important to be aware that bisphosphonates are not all the same, and patient responses to treatment may vary depending on which bisphosphonates they are taking. Due to recent concerns about bisphosphonate-induced osteonecrosis of the jaw, this paper provides guidance to help the clinician regarding decision-making about preventive and interventional dental treatment when their patient has been prescribed a bisphosphonate. An understanding of current bisphosphonates, their uses, their structural differences and their intended actions helps to improve clinical decision-making. Current knowledge regarding the effects of osteoporosis/osteopenia on periodontal diseases and alveolar bone loss is inconclusive. It is certainly clear that bisphosphonates are not indicated as an adjunctive treatment as part of periodontal therapy because of the risk of osteonecrosis. Regarding implant placement, there are no convincing data that dental implant placement is contraindicated in the osteoporotic patient. However, patients should understand the small risk of compromised bone healing following implant placement if the patient has been taking bisphosphonates. Due to the risks of osteonecrosis, dental clinicians should work closely with their medical colleagues prior to the physician prescribing oral bisphosphonates. Ideally, optimal periodontal and dental health should be established before the patient commences bisphosphonate therapy.