Periostin, dentin matrix protein 1 and P2rx7 ion channel in human teeth and periodontal ligament.

The periostin is a matricellular protein present in the human periodontal ligament and human dental pulp-derived cells lines, that up-regulates the in vitro expression of some genes involved in the dentin mineralization, such as dentin matrix protein 1 and P2x7-ion channel receptor. Here we investigated the distribution of periostin in human teeth and periodontal ligaments, mapping in parallel the localization of dentin matrix protein 1 and P2x7-ion channel receptor to establish whether or not they are expressed in the same places as periostin. The periodontal ligament and the subodontoblastic layer of the dental pulp displayed strong periostin immunoreactivity, whereas dentin matrix protein 1 was detected in the periodontal ligament co-localized with periostin in the vicinity of the cement. The P2x7 ion channel receptor was regularly absent in both the periodontal ligament and dental tissues, but in some cases, it was observed in the odontoblasts. Present results demonstrate the occurrence of periostin in the healthy adult human tooth without co-localization with proteins involved in tooth mineralization, the expression of which it regulates. These results might serve as a baseline for future studies on pathological conditions.

Osteoprotegerin and zoledronate bone effects during orthodontic tooth movement.

OBJECTIVES: To assess the effects of local delivery of recombinant fusion protein osteoprotegerin (OPG-Fc) and bisphosphonate zoledronate on bone and periodontal ligament in a rat tooth movement model. MATERIALS AND METHODS: Maxillary first molars of 36 male Sprague-Dawley rats were displaced mesially using a calibrated spring connected to an anterior mini-screw. Two different drugs were used: a single dose of Zoledronate (16 µg) and a twice-weekly dose of OPG-Fc (5.0 mg/kg) were injected. Tooth movement was measured on scanned plaster casts. Structural and immunohistochemical analysis of the orthodontic-induced changes in bone included receptor activator of nuclear factor ĸ (RANK), Runx, type 1 collagen, matrix metalloproteinases (MMPs) 2 and 9, tissue inhibitors of metalloproteinases (TIMPs) 1 and 2, and vimentin. RESULTS: Both groups showed a reduction in mesial molar displacement. Animals receiving OPG-Fc demonstrated only 52%, 31%, and 21% of the total mesial molar displacement compared to control rats at 7, 14, and 21 days, respectively (*p < 0.001). For rats receiving zoledronate tooth displacement decreased significantly with 52%, 46% and 30%, respectively (*p < 0.001). At 14 and 21 days, OPG-Fc group showed significantly less molar displacement than the zoledronate group (*p < 0.001). RANK, Runx, vimentin, MMP-9 and tissues-inhibitor metalloproteinase 1 immunoreactivity were reduced in zoledronate treated animals and even more in OPG treated animals. CONCLUSION: Local delivery of OPG-Fc or zoledronate inhibits bone resorption and therefore tooth movement. OPG-Fc was more effective than zoledronate in blocking the action of osteoclasts.