title: Effect of occlusal hypofunction and its recovery on the three-dimensional architecture of mandibular alveolar bone in growing rats.
abstract: BACKGROUND
  Normal occlusion is very important for physiological structure of mandible. However, the details of influences of occlusal hypofunction and its recovery on the three-dimensional architecture of mandibular alveolar bone in growing rats are still lacking.
  
  
  METHODS
  Forty-eight growing male Sprague-Dawley rats were randomly divided into normal (n = 24), hypofunctional (n = 12), and recovery (n = 12) groups. The hypofunction group was developed by inserting a bite-raising appliance between the maxillary and mandibular incisors of the rats. Two weeks after insertion, the appliance was removed to result in the recovery group; the experiment continued for two additional weeks. The experimental animals and control animals were killed weekly. In addition to measuring the body weight and masseter muscle weight of the rats, the histomorphology and microstructure of the mandibular alveolar bone were scanned using microcomputed tomography.
  
  
  RESULTS
  A lighter masseter muscle and a higher and narrower alveolar process were observed in the hypofunction group compared with the control animals (P < 0.05). Mandibular remodeling also occurred in the hypofunctional group, as demonstrated by a smaller trabecular cross-sectional area, looser trabecular bone, decreased bone volume fraction, trabecular thickness, trabecular number, and increased bone surface density and trabecular separation, especially at week 2 (P < 0.05). After removing the anterior bite-opening appliance, the altered masseter muscle weight and architecture of the mandibular alveolar bone were gradually reversed and reached normal levels at the end of the experiment (P > 0.05).
  
  
  CONCLUSIONS
  A loss of occlusal stimuli can lead into mandibular alveolar bone remodeling, and the recovery of occlusion can restore the altered mandibular architecture in growing rats.
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi Province, People's Republic of China.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi Province, People's Republic of China. Electronic address: zuolinj@fmmu.edu.cn.
authors.forename: Zuo-lin
authors.initials: ZL
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Military Stomatology, Department of General Dentistry & Emergency, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi Province, People's Republic of China. Electronic address: lqaq726@163.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
mesh_terms: D000539:Alveolar Process / Q000000981:diagnostic imaging / Q000254:growth & development / Q000502:physiology; D000818:Animals; D016723:Bone Remodeling / Q000502:physiology; D003766:Dental Occlusion; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000502:physiology; D008297:Male; D008310:Malocclusion / Q000000981:diagnostic imaging / Q000473:pathology*; D008334:Mandible / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000502:physiology; D008406:Masseter Muscle / Q000000981:diagnostic imaging / Q000254:growth & development / Q000502:physiology; D008437:Maxilla / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000502:physiology; D009929:Organ Size; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D055114:X-Ray Microtomography / Q000379:methods
keywords: Mandible; Micro-CT; Microarchitecture; Occlusal hypofunction; Rat