title: Effects of Decreased Occlusal Loading during Growth on the Mandibular Bone Characteristics.
abstract: BACKGROUND
  Bone mass and mineralization are largely influenced by loading. The purpose of this study was to evaluate the reaction of the entire mandibular bone in response to decreased load during growth. It is hypothesized that decreased muscular loading will lead to bone changes as seen during disuse, i.e. loss of bone mass.
  
  
  RESULTS
  Ten 21-day-old Wistar strain male rats were divided into two groups (each n=5) and fed on either a hard- or soft-diet for 11 weeks. Micro-computed tomography was used for the investigation of bone mineralization, bone volume, bone volume fraction (BV/TV) and morphological analysis. Mandibular mineralization patterns were very consistent, showing a lower degree of mineralization in the ramus than in the corpus. In the soft-diet group, mineralization below the molars was significantly increased (p<0.05) compared to the hard diet group. Also, bone volume and BV/TV of the condyle and the masseter attachment were decreased in the soft-diet group (p<0.05). Morphological analysis showed inhibited growth of the ramus in the soft-diet group (p<0.05).
  
  
  CONCLUSIONS
  Decreased loading by a soft diet causes significant changes in the mandible. However, these changes are very region-specific, probably depending on the alterations in the local loading regime. The results suggest that muscle activity during growth is very important for bone quality and morphology.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Tokushima University Graduate School of Oral Sciences, Tokushima, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Hichijo
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan; Department of Orthodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Kawai
authors.affiliation: Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), Research Institute MOVE, University of Amsterdam and VU University Amsterdam, Amsterdam, Netherlands.
authors.forename: Leo J
authors.initials: LJ
authors.lastname: van Ruijven
authors.affiliation: Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), Research Institute MOVE, University of Amsterdam and VU University Amsterdam, Amsterdam, Netherlands.
authors.forename: Geerling E J
authors.initials: GE
authors.lastname: Langenbach
mesh_terms: D000818:Animals; D015519:Bone Density; D002113:Calcification, Physiologic; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging* / Q000254:growth & development*; D008406:Masseter Muscle / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D055114:X-Ray Microtomography