Shuji Oishi1, Yasuhiro Shimizu1, Jun Hosomichi2, Yoichiro Kuma1, Hisashi Nagai3, Hideyuki Maeda4, Risa Usumi-Fujita1, Sawa Kaneko1, Chisa Shitano1, Jun-ichi Suzuki5, Ken-ichi Yoshida4, Takashi Ono1. 1. Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. 2. Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Electronic address: hosomichi.orts@tmd.ac.jp. 3. Department of Forensic Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. 4. Department of Forensic Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Department of Forensic Medicine, Graduate School of Medicine, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan. 5. Department of Advanced Clinical Science and Therapeutics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Abstract
OBJECTIVES: To investigate intermittent hypoxia (IH) induced changes in craniofacial morphology and bone mineral density (BMD) in the mandible of growing rats. DESIGN: Seven-week-old male Sprague-Dawley rats were exposed to IH for 4 days or 3 weeks. Sham-operated rats simultaneously breathed room air. Lateral and transverse cephalometric radiographs of the craniofacial region were obtained, and the linear distances between cephalometric landmarks were statistically analyzed. BMD and bone microstructure of the mandible were evaluated using micro-computed tomography (micro-CT). RESULTS: Cephalometric analyses demonstrated that exposure to IH only in the two groups for 3 weeks decreased the size of the mandibular and viscerocranial bones, but not that of the neurocranial bones, in early adolescent rats. These findings are consistent with upper airway narrowing and obstructive sleep apnea (OSA). Micro-CT showed that IH increased the BMD in the cancellous bone of the mandibular condyle and the inter-radicular alveolar bone in the mandibular first molar (M1) region. CONCLUSIONS: This study is the first to identify growth retardation of the craniofacial bones in an animal model of sleep apnea. Notably, 3 weeks of IH can induce multiple changes in the bones around the upper airway in pubertal rats, which can enhance upper airway narrowing and the development of OSA. The reproducibility of these results supports the validity and usefulness of this model. These findings also emphasize the critical importance of morphometric evaluation of patients with OSA.
OBJECTIVES: To investigate intermittent hypoxia (IH) induced changes in craniofacial morphology and bone mineral density (BMD) in the mandible of growing rats. DESIGN: Seven-week-old male Sprague-Dawley rats were exposed to IH for 4 days or 3 weeks. Sham-operated rats simultaneously breathed room air. Lateral and transverse cephalometric radiographs of the craniofacial region were obtained, and the linear distances between cephalometric landmarks were statistically analyzed. BMD and bone microstructure of the mandible were evaluated using micro-computed tomography (micro-CT). RESULTS: Cephalometric analyses demonstrated that exposure to IH only in the two groups for 3 weeks decreased the size of the mandibular and viscerocranial bones, but not that of the neurocranial bones, in early adolescent rats. These findings are consistent with upper airway narrowing and obstructive sleep apnea (OSA). Micro-CT showed that IH increased the BMD in the cancellous bone of the mandibular condyle and the inter-radicular alveolar bone in the mandibular first molar (M1) region. CONCLUSIONS: This study is the first to identify growth retardation of the craniofacial bones in an animal model of sleep apnea. Notably, 3 weeks of IH can induce multiple changes in the bones around the upper airway in pubertal rats, which can enhance upper airway narrowing and the development of OSA. The reproducibility of these results supports the validity and usefulness of this model. These findings also emphasize the critical importance of morphometric evaluation of patients with OSA.
Authors: H Eimar; H Saltaji; S Ghorashi; D Isfeld; J E MacLean; D Gozal; D Graf; C Flores-Mir Journal: Osteoporos Int Date: 2017-01-18 Impact factor: 4.507