Mechanisms of alveolar bone remodeling

The maintenance of bone is achieved by a fine balance between bone formation and bone resorption. The differentiation and activation of osteoclasts are tightly regulated by osteoblasts. Osteoblasts express at least two cytokines essential for osteoclast differentiation; they are receptor activator of NF-kappaB ligand (RANKL) and macrophage colony stimulating factor (M-CSF). On the other hand, differentiation of osteoblasts is regulated by the transcription factors Runx2 and Osterix. The recent progress of genetic experiments has revealed that osteoclasts also regulate the differentiation of osteblasts in vivo. This review describes the recent studies on the communication between osteoblasts and osteoclasts in the process of bone remodeling.