title: Topical and intermittent application of parathyroid hormone recovers alveolar bone loss in rat experimental periodontitis.
abstract: OBJECTIVE
  Periodontitis is characterized by periodontal tissue inflammation and alveolar bone loss. The intermittent administration of parathyroid hormone (PTH), a major regulator of bone remodeling, has been demonstrated to stimulate osteoblastic activity. Although the systemic administration of PTH has been reported to protect against periodontitis-associated bone loss, the effect of the topical administration of PTH is unclear. In this study, the effect of intermittent administration of PTH on osteoblastic differentiation was examined in cultured calvaria cells and then the effect of topical and intermittent administration of PTH was determined by measuring the recovery of alveolar bone loss after inducing experimental periodontitis in rats.
  
  
  METHODS
  Alkaline phosphatase activity and bone nodule formation were measured in fetal rat calvaria cells. Experimental periodontitis was induced by placing nylon ligature around rat maxillary molars for 20 d. After ligature removal (day 0), PTH was topically injected into buccal gingiva three times a week for 10 wk. Micro-computed tomography analysis and histological examination were performed on days 35 and 70.
  
  
  RESULTS
  Intermittent exposure of PTH in calvaria cells increased alkaline phosphatase activity and bone nodule formation by 1.4- and 2.4-fold, respectively. Ligature procedures induced marked alveolar bone loss around the molars on day 0 and greater bone recovery was observed in the PTH-treated rats on day 70. An increase in osteoid formation on the surface of alveolar bone was detected in the PTH-treated rats.
  
  
  CONCLUSIONS
  Intermittent treatment with PTH stimulated osteoblastic differentiation in fetal rat calvaria cell cultures, and topical and intermittent administration of PTH recovered alveolar bone loss in rat experimental periodontitis.
authors: Department of Periodontology and Endodontology, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan.
authors: K
authors: K
authors: Tokunaga
authors: H
authors: H
authors: Seto
authors: H
authors: H
authors: Ohba
authors: C
authors: C
authors: Mihara
authors: H
authors: H
authors: Hama
authors: M
authors: M
authors: Horibe
authors: S
authors: S
authors: Yoneda
authors: T
authors: T
authors: Nagata
mesh_terms: D000287:Administration, Topical; D000469:Alkaline Phosphatase / Q000096:biosynthesis; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000188:drug therapy*; D000818:Animals; D001861:Bone Regeneration / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004334:Drug Administration Schedule; D005333:Fetus; D007091:Image Processing, Computer-Assisted; D008026:Ligation; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010281:Parathyroid Hormone / Q000008:administration & dosage*; D010518:Periodontitis / Q000188:drug therapy*; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D012886:Skull / Q000166:cytology; D055114:X-Ray Microtomography
chemical_list: D010281:Parathyroid Hormone; D000469:Alkaline Phosphatase