title: Normal masticatory function partially protects the rat mandibular bone from estrogen-deficiency induced osteoporosis.
abstract: OBJECTIVE
  In a previous study we showed that mandibular alveolar (trabecular) bone appears to be less sensitive to estrogen deficiency than the proximal tibia spongiosa. We hypothesized that the mechanical loading of the alveolar process during mastication may protect the alveolar bone from the detrimental effects observed in other skeletal sites. To test this hypothesis we compared the effect of ovariectomy on the mandibular alveolar bone and the proximal tibia spongiosa of rats fed either a normal (hard) or a soft diet.
  
  
  METHODS
  Forty six-month-old female Sprague-Dawley rats underwent trans-abdominal ovariectomy (OVX) or sham operation (SHAM). Half of the animals received their food in the usual form of pellets (hard consistency), while the other half received a soft, porridge-like, isocaloric diet of identical composition (soft consistency). Micro-computed tomographic histomorphometry was used to evaluate the trabecular micro-architecture. A two-factor analysis of variance was used to test for effects and interaction of ovariectomy and/or soft diet.
  
  
  RESULTS
  OVX had a significantly negative effect on the proximal tibia spongiosa (all parameters under study except trabecular thickness; p<0.001) and on the mandibular alveolar bone (trabecular number and spacing; p<0.05). Soft diet led to a further decrease of mandibular BV/TV (p<0.01), trabecular thickness (p<0.05) and number (p<0.05), as well as increase of separation (p<0.001). A significant interaction was observed between OVX and soft diet concerning the mandibular BV/TV, as well as trabecular thickness and spacing (p<0.05).
  
  
  CONCLUSIONS
  Normal (hard) diet limited significantly the negative effects of estrogen deficiency on mandibular alveolar bone micro-architecture four months after ovariectomy.
authors.affiliation: Division of Bone Diseases [WHO Collaborating Center for Osteoporosis Prevention], Department of Internal Medicine Specialties, University Hospitals of Geneva and Faculty of Radiology, Geneva, Switzerland; Department of Orthodontics, Faculty of Medicine, University of Geneva, Geneva, Switzerland. Electronic address: anestis.mavropoulos@unige.ch.
authors.forename: Anestis
authors.initials: A
authors.lastname: Mavropoulos
authors.affiliation: Department of Orthodontics, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Stavros
authors.initials: S
authors.lastname: Kiliaridis
authors.affiliation: Division of Bone Diseases [WHO Collaborating Center for Osteoporosis Prevention], Department of Internal Medicine Specialties, University Hospitals of Geneva and Faculty of Radiology, Geneva, Switzerland.
authors.forename: René
authors.initials: R
authors.lastname: Rizzoli
authors.affiliation: Division of Bone Diseases [WHO Collaborating Center for Osteoporosis Prevention], Department of Internal Medicine Specialties, University Hospitals of Geneva and Faculty of Radiology, Geneva, Switzerland.
authors.forename: Patrick
authors.initials: P
authors.lastname: Ammann
mesh_terms: D000539:Alveolar Process / Q000503:physiopathology; D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density; D004967:Estrogens / Q000172:deficiency; D005260:Female; D008334:Mandible / Q000503:physiopathology*; D008409:Mastication; D010024:Osteoporosis / Q000503:physiopathology*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000503:physiopathology; D055114:X-Ray Microtomography
chemical_list: D004967:Estrogens
keywords: Bone biomechanics; Bone histomorphometry; Mandibular alveolar bone; Masticatory function; Osteoporosis; Ovariectomy; Proximal tibia