title: [Effect of experimental occlusal hypofunction and its recovery on mandibular bone mineral density in rats].
abstract: OBJECTIVE
  To examine the effect of experimental occlusal hypofunction and recovery on mandibular bone mineral density (BMD).
  
  
  METHODS
  Sixty Sprague-Dawley (SD) male rats were randomly divided into experimental occlusal hypofunction group,experimental occlusal recovery group and control group, with 20 rats in each group. They were killed under deep anaesthesia at 0-, 2-, 4-, 6-, and 8-week, after that the mandibles were immediately removed for measuring the BMD of cancellous and cortical bone in the first molar region with micro-CT. SPSS12.0 software package was used for statistical analysis.
  
  
  RESULTS
  At 4-week, the cancellous bone density at the bifurcation of the root and the root apex decreased in the hypofunction group (P<0.05), whereas the cancellous bone density on the buccal and lingual sides became lower at 6-week compared with the control group (P<0.01), and they all lasted until the end of the experiment (P<0.01). In the recovery group, the density on the buccal side, lingual side and at the root apex except for the bifurcation of the root had recovered to normal level compared with the control group at 8-week. At 6- and 8-week, cortical bone density in the hypofunction group had reduced in the lingual middle and lingual basal cortical bone areas (P<0.05). However, there was no difference between the buccal side in hypofunction group and control group at all the time-points. The same results were observed between the buccal and lingual sides in the recovery group compared with control group.
  
  
  CONCLUSIONS
  Experimental occlusal hypofunction could result in the decrease of BMD in both cancellous and cortical bone in rats. Recovery of occlusal hypofunction may restore decreased BMD in mandible.
authors.affiliation: Department of Stomatology, Zhejiang Hospital, Hangzhou, Zhejiang Province, China. zhouguofeng1976@163.com
authors.forename: Gou-feng
authors.initials: GF
authors.lastname: Zhou
authors.forename: Li-xin
authors.initials: LX
authors.lastname: Xiang
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Xiao-feng
authors.initials: XF
authors.lastname: Li
mesh_terms: D000818:Animals; D015519:Bone Density; D003766:Dental Occlusion; D008297:Male; D008334:Mandible; D008963:Molar; D051381:Rats; D017207:Rats, Sprague-Dawley; D055114:X-Ray Microtomography