title: Intermittent administration of parathyroid hormone ameliorates periapical lesions in mice.
abstract: BACKGROUND
  Intermittent administration of parathyroid hormone (PTH) promotes oral osseous wound healing and protects against ligature-induced alveolar bone loss. However, its therapeutic value on periapical periodontitis is unknown. The goal of this study was to determine the effect of intermittent PTH administration on the progression of periapical periodontitis.
  
  
  METHODS
  Seven lymphotoxin alpha-deficient mice received pulp exposures of mandibular first and second molars. Exposed pulp in the right mandible was covered with plaque-contaminated fibrin, whereas exposed pulp in the left mandible was left open. After 4 weeks, the periapical tissues were examined to determine the effect of plaque-contaminated fibrin to induce periapical lesions. Fourteen mice received pulp exposure covered with plaque-contaminated fibrin. PTH (40 μg/kg/d) was administered intermittently to half of the mice for 3 weeks beginning 1 week after pulp exposure. The remaining half received saline injections as the vehicle control. At sacrifice, mandibles and tibiae were harvested and processed for histologic examination. Evaluation of neutrophils and blood vessels was performed after staining with immunofluorescence, and periradicular bone was histomorphometrically analyzed.
  
  
  RESULTS
  The exposed pulp covered with plaque-contaminated fibrin resulted in significantly larger periapical lesions compared with the control. Intermittent PTH administration reduced the size of periapical lesions significantly. Significantly less neutrophil infiltration around the root apex was found in PTH-treated animals compared with the control.
  
  
  CONCLUSIONS
  PTH treatment suppressed periapical inflammation by reducing neutrophil infiltration and protected against tissue destruction by periapical periodontitis.
authors: Division of Prosthodontics, Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan; Department of Oral Rehabilitation, Section of Oral Implantology, Fukuoka, Japan.
authors: Masato
authors: M
authors: Otawa
authors: Division of Prosthodontics, Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan; Dental and Oral Medical Center, Kurume University School of Medicine, Kurume, Fukuoka, Japan.
authors: Ryuichiro
authors: R
authors: Tanoue
authors: Department of Oral Rehabilitation, Section of Oral Implantology, Fukuoka, Japan.
authors: Hirofumi
authors: H
authors: Kido
authors: Department of Morphological Biology, Fukuoka Dental College, Fukuoka, Japan.
authors: Yoshihiko
authors: Y
authors: Sawa
authors: Division of Prosthodontics, Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan. Electronic address: yamashit@umich.edu.
authors: Junro
authors: J
authors: Yamashita
mesh_terms: D000818:Animals; D008817:Mice, Mutant Strains; D020556:Neutrophil Infiltration; D010281:Parathyroid Hormone / Q000008:administration & dosage* / Q000627:therapeutic use; D010485:Periapical Periodontitis / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology
chemical_list: D010281:Parathyroid Hormone
keywords: Lymphotoxin alpha; neutrophil infiltration; parathyroid hormone; periapical periodontitis
references: N Engl J Med. 2010 Dec 16;363(25):2396-405
references: 20950166
references: J Bone Joint Surg Am. 2011 Sep 7;93(17):1583-7
references: 21915572
references: J Bone Miner Res. 2002 May;17(5):808-16
references: 12009011
references: J Bone Miner Res. 2002 Nov;17(11):2038-47
references: 12412812
references: J Endod. 2003 Mar;29(3):194-200
references: 12669880
references: J Endod. 2003 Apr;29(4):252-6
references: 12701773
references: J Dent Res. 2003 Oct;82(10):791-5
references: 14514758
references: J Endod. 1977 Aug;3(8):292-300
references: 268403
references: J Endod. 2012 Aug;38(8):1097-100
references: 22794213
references: Implant Dent. 2013 Feb;22(1):71-6
references: 23296032
references: J Dent Res. 2013 Jun;92(6):553-9
references: 23611925
references: J Immunol Methods. 2013 Aug 30;394(1-2):49-54
references: 23672778
references: J Immunol. 2013 Aug 15;191(4):1785-91
references: 23863904
references: J Periodontol. 2014 Jan;85(1):24-33
references: 23688101
references: J Endod. 2014 Feb;40(2):155-63
references: 24461396
references: Osteoporos Int. 2014 Mar;25(3):1141-50
references: 24301537
references: Immunology. 2008 Dec;125(4):503-9
references: 18479349
references: J Clin Endocrinol Metab. 1979 Apr;48(4):582-4
references: 429503
references: J Lab Clin Med. 1981 Feb;97(2):291-8
references: 7192722
references: J Clin Invest. 1983 Feb;71(2):404-7
references: 6296202
references: J Biol Chem. 1984 May 10;259(9):5531-5
references: 6325439
references: Am J Nephrol. 1988;8(3):212-9
references: 2853573
references: J Am Soc Nephrol. 1990 Sep;1(3):236-44
references: 1966555
references: Am J Nephrol. 1991;11(2):102-11
references: 1951470
references: J Endod. 1991 Aug;17(8):380-3
references: 1809801
references: J Immunol. 1995 Aug 15;155(4):1685-93
references: 7636227
references: Endocrinology. 1997 Nov;138(11):4607-12
references: 9348185
references: Clin Nephrol. 1997 Dec;48(6):353-8
references: 9438093
references: J Endod. 2005 Jun;31(6):424-9
references: 15917680
references: J Endod. 2007 Jul;33(7):773-81
references: 17804311
references: J Bone Miner Res. 2008 May;23(5):621-32
references: 18086008
references: J Bone Miner Res. 2008 Aug;23(8):1257-66
references: 18348699
references: J Dent Res. 2008 Dec;87(12):1155-9
references: 19029085
references: J Endod. 2009 Sep;35(9):1229-33
references: 19720221
references: Blood. 2010 Sep 23;116(12):2173-82
references: 20566898