title: Effects of bleaching on osteoclast activity and their modulation by osteostatin and fibroblast growth factor 2.
abstract: OBJECTIVE
  Dental bleaching with H2O2 is a common daily practice in dentistry to correct discoloration of anterior teeth. The aim of this study has been to determine whether this treatment of human teeth affects growth, differentiation and activity of osteoclast-like cells, as well as the putative modulatory action of osteostatin and fibroblast growth factor 2 (FGF-2).
  
  
  METHODS
  Previously to the in vitro assays, structural, physical-chemical and morphological features of teeth after bleaching were studied. Osteoclast-like cells were cultured on human dentin disks, pre-treated or not with 38% H2O2 bleaching gel, in the presence or absence of osteostatin (100 nM) or FGF-2 (1 ng/ml). Cell proliferation and viability, intracellular content of reactive oxygen species (ROS), pro-inflammatory cytokine (IL-6 and TNFα) secretion and resorption activity were evaluated.
  
  
  RESULTS
  Bleaching treatment failed to affect either the structural or the chemical features of both enamel and dentin, except for slight morphological changes, increased porosity in the most superficial parts (enamel), and a moderate increase in the wettability degree. In this scenario, bleaching produced an increased osteoclast-like cell proliferation but decreased cell viability and cytokine secretion, while it augmented resorption activity on dentin. The presence of either osteostatin or FGF-2 reduced the osteoclast-like cell proliferation induced by bleaching. FGF-2 enhanced ROS content, whereas osteostatin decreased ROS but increased TNFα secretion. The bleaching effect on resorption activity was increased by osteostatin, but this effect was less evident with FGF-2.
  
  
  CONCLUSIONS
  These findings further confirm the deleterious effects of tooth bleaching by affecting osteoclast growth and function as well as different modulatory actions of osteostatin and FGF-2.
authors.affiliation: Departamento de Salud Oral, Facultad de Odontología, Universidad Nacional de Colombia, Sede Bogotá, Colombia. Electronic address: ctorresr@unal.edu.co.
authors.forename: Carolina
authors.initials: C
authors.lastname: Torres-Rodríguez
authors.affiliation: Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain. Electronic address: portoles@quim.ucm.es.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Portolés
authors.affiliation: Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain. Electronic address: conchitamatesanz@hotmail.com.
authors.forename: M Concepción
authors.initials: MC
authors.lastname: Matesanz
authors.affiliation: Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain. Electronic address: javilinares_88@hotmail.com.
authors.forename: Javier
authors.initials: J
authors.lastname: Linares
authors.affiliation: Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain. Electronic address: mjfeito@pdi.ucm.es.
authors.forename: M José
authors.initials: MJ
authors.lastname: Feito
authors.affiliation: Departamento de Química Inorgánica y Bioinorgánica, Facultad de Farmacia, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Hospital 12 de Octubrei+12, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Spain. Electronic address: ibarba@ucm.es.
authors.forename: Isabel
authors.initials: I
authors.lastname: Izquierdo-Barba
authors.affiliation: Laboratorio de Metabolismo Mineral y Óseo, Instituto de Investigación Sanitaria (IIS)-Fundación Jiménez Díaz, Madrid, Spain. Electronic address: PEsbrit@fjd.es.
authors.forename: Pedro
authors.initials: P
authors.lastname: Esbrit
authors.affiliation: Departamento de Salud Oral, Facultad de Odontología, Universidad Nacional de Colombia, Sede Bogotá, Colombia; Departamento de Bioquímica y Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain; Departamento de Química Inorgánica y Bioinorgánica, Facultad de Farmacia, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Hospital 12 de Octubrei+12, Plaza Ramón y Cajal s/n, 28040 Madrid, Spain. Electronic address: vallet@ucm.es.
authors.forename: María
authors.initials: M
authors.lastname: Vallet-Regí
mesh_terms: D000293:Adolescent; D000327:Adsorption; D000328:Adult; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003804:Dentin / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D044162:Parathyroid Hormone-Related Protein / Q000378:metabolism*; D010316:Particle Size; D010446:Peptide Fragments / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013499:Surface Properties; D014073:Tooth Bleaching / Q000009:adverse effects*; D017155:Wettability; D055815:Young Adult
chemical_list: C416003:FGF20 protein, human; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D017382:Reactive Oxygen Species; C071784:parathyroid hormone-related protein (107-111); D005346:Fibroblast Growth Factors; D006861:Hydrogen Peroxide
keywords: Dental bleaching; External cervical resorption; Fibroblast growth factor 2; Osteoclast; Osteostatin