Intermittent hypoxia causes mandibular growth retardation and macroglossia in growing rats.
BACKGROUND
In this study, we aimed to examine the role of intermittent hypoxia (IH) in dentofacial morphologic changes in growing rats.


METHODS
Seven-week-old male rats were exposed to IH at 20 cycles per hour (nadir of 4% oxygen to peak of 21% oxygen) for 8 hours per day for 6 weeks. Control rats were exposed to normoxia (N). Maxillofacial growth was compared between the 2 groups by linear measurements on cephalometric radiographs. To examine the dental arch morphology, study models and microcomputed tomography images of the jaws were taken. Additionally, tongue size was measured.


RESULTS
The gonial angle and the ramus of the mandible were smaller in the IH group than in the N group, whereas the body weights were not different between the 2 groups. Morphometric analysis of the dentition showed a significantly wider mandibular dentition and narrower maxillary dentition in the IH than in the N group. The relative width (+4.2 %) and length (tongue apex to vallate papillae, +3.5 %) of the tongue to the mandible were significantly greater in the IH group than in the N group.


CONCLUSIONS
IH induced dentofacial morphologic discrepancies in growing rats.
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: hosomichi.orts@tmd.ac.jp.
Jun
J
Hosomichi
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Yo-Ichiro
YI
Kuma
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Shuji
S
Oishi
Department of Forensic Medicine, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Hisashi
H
Nagai
Department of Forensic Medicine, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Hideyuki
H
Maeda
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Risa
R
Usumi-Fujita
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Yasuhiro
Y
Shimizu
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Sawa
S
Kaneko
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Chisa
C
Shitano
Department of Advanced Clinical Science and Therapeutics, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Jun-Ichi
JI
Suzuki
Department of Forensic Medicine, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Ken-Ichi
KI
Yoshida
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Takashi
T
Ono
D000818:Animals; D006130:Growth Disorders / Q000209:etiology*; D000860:Hypoxia / Q000150:complications*; D008260:Macroglossia / Q000209:etiology*; D008297:Male; D008334:Mandible / Q000254:growth & development*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020181:Sleep Apnea, Obstructive / Q000150:complications