Alveolar bone osteocytes also express RANKL, and it has recently been demonstrated that especially osteocyte-expressed RANKL could be crucial in the initiation of periodontitis as demonstrated in a RANKL knock-out mouse model with a targeted disruption of RANKL in osteocytes [8], reviewed by De Vries and Huesa [9]. This evidence concerns the gene TNFSF11 and periodontitis.