title: Osteoclasts in the dental microenvironment: a delicate balance controls dental histogenesis.
abstract: The impact of osteoclast activity on dental development has been previously analyzed but in the context of severe osteopetrosis. The present study sought to investigate the effects of osteoclast hypofunction,present in Msx2 gene knockin mutant mice (Msx2-/-), and hyperfunction, in transgenic mice driving RANK over-expression in osteoclast precursors (RANK(Tg)), on tooth development. In Msx2-/- mice, moderate osteopetrosis was observed, occurring exclusively in the periodontal region. Microradiographical and histological analyses revealed an abnormal dental epithelium histogenesis that gave rise to odontogenic tumor-like structures. This led to impaired tooth eruption, especially of the third mandibular molars. In RANK(Tg) mice, root histogenesis showed site-specific upregulation of dental cell proliferation and differentiation rates. This culminated in roots with a reduced diameter and pulp size albeit of normal length. These two reverse experimental systems will enable the investigation of distinctive dental cell and osteoclast communication in normal growth and tumorigenesis.
authors.affiliation: INSERM, UMR 872, Cordeliers Research Center, Team 5, Laboratory of Oral Molecular Physiopathology, Universities Paris-Diderot, Pierre and Marie Curie and Paris-Descartes, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Berdal
authors.forename: B
authors.initials: B
authors.lastname: Castaneda
authors.forename: M
authors.initials: M
authors.lastname: Aïoub
authors.forename: J R
authors.initials: JR
authors.lastname: Néfussi
authors.forename: C
authors.initials: C
authors.lastname: Mueller
authors.forename: V
authors.initials: V
authors.lastname: Descroix
authors.forename: F
authors.initials: F
authors.lastname: Lézot
mesh_terms: D000818:Animals; D060833:Cellular Microenvironment; D018398:Homeodomain Proteins / Q000378:metabolism; D008334:Mandible / Q000000981:diagnostic imaging / Q000254:growth & development / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D008963:Molar / Q000000981:diagnostic imaging / Q000254:growth & development / Q000378:metabolism / Q000473:pathology; D009154:Mutation / Q000235:genetics; D010010:Osteoclasts / Q000378:metabolism / Q000473:pathology*; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000378:metabolism; D014070:Tooth / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000378:metabolism / Q000473:pathology*; D055114:X-Ray Microtomography
chemical_list: D018398:Homeodomain Proteins; C084119:MSX2 protein; D053246:Receptor Activator of Nuclear Factor-kappa B