title: Effects of pulpectomy on the amount of root resorption during orthodontic tooth movement.
abstract: BACKGROUND
  Previous studies have revealed that orthodontic force affects dental pulp via the rupture of blood vessels and vacuolization of pulp tissues. We hypothesized that pulp tissues express inflammatory cytokines and regulators of odontoclast differentiation after excess orthodontic force. The purpose of this study was to investigate the effects of tensile force in human pulp cells and to measure inflammatory root resorption during tooth movement in pulpless rat teeth.
  
  
  METHODS
  After cyclic tensile force application in human pulp cells, gene expression and protein concentration of macrophage colony-stimulating factor, receptor activator of nuclear factor kappa-B ligand, interleukin-1 beta, and tumor necrosis factor alpha were determined by real-time polymerase chain reaction and enzyme-linked immunoassay. Moreover, the role of the stretch-activated channel was evaluated by gadolinium (Gd(3+)) treatment. The upper right first molars of 7-week Wistar rats were subjected to pulpectomy and root canal filling followed by mesial movement for 6 months.
  
  
  RESULTS
  The expression of cytokine messenger RNAs and proteins in the experimental group peaked with loading at 10-kPa tensile force after 48 hours (P < .01). Gd(3+) reduced the expression of these cytokine messenger RNAs and protein concentrations (P < .01). The amount of inflammatory root resorption was significantly larger in the control teeth than the pulpectomized teeth (P < .05).
  
  
  CONCLUSIONS
  This study shows that tensile forces in the pulp cells enhance the expression of various cytokines via the S-A channel, which may lead to inflammatory root resorption during tooth movement. It also suggests that root canal treatment is effective for progressive severe inflammatory root resorption during tooth movement.
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan. Electronic address: motumo@hiroshima-u.ac.jp.
authors.forename: Masato
authors.initials: M
authors.lastname: Kaku
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Sumi
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Hanaka
authors.initials: H
authors.lastname: Shikata
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kojima
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Motokawa
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Fujita
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Tanimoto
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanne
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001696:Biomechanical Phenomena; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology* / Q000502:physiology; D005682:Gadolinium / Q000494:pharmacology; D006801:Humans; D053583:Interleukin-1beta / Q000032:analysis; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000032:analysis / Q000037:antagonists & inhibitors; D016173:Macrophage Colony-Stimulating Factor / Q000032:analysis; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008963:Molar / Q000503:physiopathology; D011670:Pulpectomy / Q000379:methods*; D053245:RANK Ligand / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012391:Root Resorption / Q000209:etiology*; D013314:Stress, Mechanical; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000379:methods*; D019553:Tooth, Nonvital / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D055815:Young Adult
chemical_list: D053583:Interleukin-1beta; D051036:Large-Conductance Calcium-Activated Potassium Channels; D053245:RANK Ligand; C505688:TNFSF11 protein, human; D014409:Tumor Necrosis Factor-alpha; D016173:Macrophage Colony-Stimulating Factor; D005682:Gadolinium
keywords: Odontclast; orthodontic tooth movement; pulp cells; pulpectomy; root resorption; tensile forces