title: Short-term PTH administration increases dentine apposition and microhardness in mice.
abstract: OBJECTIVE
  The purpose of this study is to investigate the effects of intermittent parathyroid hormone (PTH) administration on the apposition rate and structural features of dentine from mouse incisors.
  
  
  METHODS
  Young male A/J Unib mice were treated daily for 6 and 10 days with 40 μg/kg of hPTH 1-34 or a vehicle. Dentine apposition rates measured by fluorescent labels (tetracycline and calcein) and alkaline phosphatase (ALP) plasma levels were evaluated after 6 days of treatment. Knoop microhardness testing and element content measurements in at.% of calcium (Ca), phosphorus (P), oxygen (O), and magnesium (Mg) in the peritubular and intertubular dentine were performed by Energy Dispersive X-ray (EDX) microanalysis via Scanning Electron Microscopy (SEM) after 10 days of treatment.
  
  
  RESULTS
  Histometric analysis revealed an increase of 5% in the apposition rate of dentine and 25% in the ALP plasma levels in the PTH treated group. In addition, knoop microhardness testing revealed that the animals treated with PTH had a greater microhardness (11%). EDX microanalysis showed that PTH treatment led to increases in P (23%) and Ca (53%) at.% content, as well as the Ca/P ratio (24%) in peritubular dentine. The chemical composition of intertubular dentine did not vary between the groups.
  
  
  CONCLUSIONS
  These findings indicate that intermittent administration of hPTH (1-34) increases apposition and mineralization of the dentine during young mice incisor formation.
authors.affiliation: Department of Morphology, Division of Histology, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Gustavo Narvaes
authors.initials: GN
authors.lastname: Guimarães
authors.forename: Guinéa Brasil Camargo
authors.initials: GB
authors.lastname: Cardoso
authors.forename: Lucas Zago
authors.initials: LZ
authors.lastname: Naves
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: Sergio Roberto Peres
authors.initials: SR
authors.lastname: Line
authors.forename: Marcelo Rocha
authors.initials: MR
authors.lastname: Marques
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D002118:Calcium / Q000032:analysis; D003804:Dentin / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D004577:Electron Probe Microanalysis; D005452:Fluoresceins / Q000008:administration & dosage / Q000494:pharmacology; D006244:Hardness / Q000187:drug effects; D008274:Magnesium / Q000032:analysis; D008297:Male; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D010758:Phosphorus / Q000032:analysis; D011897:Random Allocation
chemical_list: D005452:Fluoresceins; D010281:Parathyroid Hormone; D010758:Phosphorus; D000469:Alkaline Phosphatase; D008274:Magnesium; D002118:Calcium; C007740:fluorexon