title: Effects of a mandibular advancement device on genioglossus in obstructive sleep apnoea hypopnea syndrome.
abstract: OBJECTIVE
  To investigate effects of mandibular advancement device (MAD) therapy for obstructive sleep apnoea hypopnea syndrome (OSAHS) on the genioglossus contractile properties and fibre-type distribution.
  
  
  METHODS
  Thirty 6-month old male New Zealand white rabbits were randomised into three groups: OSAHS, MAD, and controls. Rabbits in Group OSAHS and Group MAD were established as OSAHS models by injection, at a dose of 2 ml hydrophilic polyacrylamide gel, via the submucous muscular layer of soft palate. Spiral computed tomography (CT) showed a significant reduced retropalatal upper airway, and apnoeas happened with an increase of Apnea Hypopnea Index (AHI) and a decrease of blood oxygen saturation during polysomnography (PSG), which indicated the OSAHS model developed successfully. OSAHS rabbits in Group MAD were fitted with a MAD made from self-curing composite resin, at 30 degrees to the upper incisors, and the mandible was guided forward 3 to 4mm. Further, spiral CT and PSG suggested MAD was effective. Rabbits in 3 groups were induced to sleep for 4-6 hours per day for 8 weeks, after which the genioglossus was removed, mounted in a tissue bath, and stimulated through platinum electrodes; maximal twitch tension, contraction time, half-relaxation time, force-frequency relationship, and fatigability were recorded. The percentage of Type I and Type II fibres was quantified.
  
  
  RESULTS
  The fatigability and percentage of Type II fibres of genioglossus increased in Group OSAHS compared with controls; this abnormality was corrected by MAD.
  
  
  CONCLUSIONS
  MAD therapy for OSAHS could prevent genioglossus fatigue and abnormal fibre-type distribution of genioglossus in OSAHS.
authors.affiliation: *Department of Orthodontics.
authors.forename: Chun-yan
authors.initials: CY
authors.lastname: Liu
authors.affiliation: *Department of Orthodontics, wangjiephd@163.com.
authors.forename: Hai-yan
authors.initials: HY
authors.lastname: Lu
authors.affiliation: **Department of Oral & Maxillofacial Surgery.
authors.forename: Fu-sheng
authors.initials: FS
authors.lastname: Dong
authors.affiliation: *Department of Orthodontics.
authors.forename: Wen-sheng
authors.initials: WS
authors.lastname: Ma
authors.affiliation: ***Department of Oral Pathology, College of Stomatology, Hebei Medical University, The Key Laboratory of Stomatology, Hebei Province, Shijiazhuang, Hebei, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.affiliation: *Department of Orthodontics.
authors.forename: Xiao-ying
authors.initials: XY
authors.lastname: Hu
authors.affiliation: *Department of Orthodontics.
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
mesh_terms: D000180:Acrylic Resins / Q000008:administration & dosage; D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D004195:Disease Models, Animal; D004558:Electric Stimulation; D007267:Injections; D008297:Male; D019186:Mandibular Advancement / Q000295:instrumentation*; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000473:pathology / Q000502:physiology; D009129:Muscle Tonus / Q000502:physiology; D009967:Orthodontic Appliances; D010100:Oxygen / Q000097:blood; D010160:Palate, Soft / Q000187:drug effects / Q000473:pathology; D017286:Polysomnography / Q000379:methods; D011817:Rabbits; D011897:Random Allocation; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D036542:Tomography, Spiral Computed / Q000379:methods; D014059:Tongue / Q000473:pathology* / Q000503:physiopathology; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D000251:Adenosine Triphosphatases; D010100:Oxygen; D000099166:Polyacrylamides