| Summary: | Osteoporosis (OP) is one of the most common debilitating conditions in the population over the age of 50. Its pathomechanism
is still not fully understood. Nowadays, in elderly population, the most common approach to control bone loss is
blocking osteoclastic activity by administration of antiresorptive drugs. Such drugs are also used for the management of
metastatic bone cancer, hypercalcemia of malignancy, and other conditions with elevated osteoclastic activity. Bisphosphonate
therapy is the first choice, but recently monoclonal antibody to RANKL (receptor activator for nuclear factorkappa
B ligand), has also been used; each with distinct mechanism of actions. Bisphosphonates irreversibly adhere to
bone minerals, and during bone remodelling, osteoclasts internalise and metabolise matrix-bound bisphosphonates.
Subsequently, they damage cytoskeletal organization and ruffled border integrity, resulting in the eventual osteoclast
apoptosis. On the other hand, denosumab blocks osteoclast neogenesis by neutralizing RANKL, which is necessary for
osteoclast precursor differentiation into mature osteoclasts. Thus, bisphosphonates acts on mature osteoclasts, while
denosumab hinders osteoclast formation from its precursors. Although their antiresorptive actions are different, recent
case reports and controlled clinical studies indicated that administration of either of these may be associated with development
of osteonecrosis of the jaw (ONJ). The fact that ONJ is associated with both bisphosphonates and denosumab
convincingly suggests that osteoclast suppression is essential in the pathomechanism of ONJ. The evidence-based,
cause-related therapy for MRONJ still remains missing. Many alternative therapeutic approaches has recently been tested
and published, amongst them, using recombinant human parathyroid hormone (rh-PTH, teriparatide) may become a
promising treatment modality
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