title: Effect of placement angle on the stability of loaded titanium microscrews in beagle jaws.
abstract: OBJECTIVE
  To evaluate the effect of insertion angle on stability of loaded titanium microscrews in beagle jaws.
  
  
  METHODS
  Forty-eight microscrews were inserted at four different angles (30°, 50°, 70°, and 90°) into the intraradicular zones of the mandibular first molars and third premolars of 12 beagles and immediately loaded with a force of 2 N for 8 weeks. Microcomputed tomography (micro-CT) and biomechanical pull-out tests were used to assess osseointegration of the interface.
  
  
  RESULTS
  All micro-CT parameters and maximum pull-out force (FMAX) of the microscrews were affected by insertion angles of microscrews. Higher micro-CT parameters and FMAX were seen for implants inserted at angles between 50° and 70° (P < .05). Excessive oblique and vertical insertion angles resulted in reduced stability (P < .05).
  
  
  CONCLUSIONS
  An insertion angle of 50° to 70° is more favorable than excessive oblique or vertical angles to achieve stability of microscrews.
authors.affiliation: State Key Laboratory of Oral Diseases, Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu, PR China.
authors.forename: Zhenrui
authors.initials: Z
authors.lastname: Xu
authors.forename: Yeke
authors.initials: Y
authors.lastname: Wu
authors.forename: Lixing
authors.initials: L
authors.lastname: Zhao
authors.forename: Yuqiao
authors.initials: Y
authors.lastname: Zhou
authors.forename: Xing
authors.initials: X
authors.lastname: Wei
authors.forename: Na
authors.initials: N
authors.lastname: Tang
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Feng
authors.forename: Tian
authors.initials: T
authors.lastname: Tang
authors.forename: Zhihe
authors.initials: Z
authors.lastname: Zhao
mesh_terms: D000818:Animals; D001641:Bicuspid / Q000000981:diagnostic imaging; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology; D001863:Bone Screws; D003764:Dental Materials / Q000737:chemistry; D004285:Dogs; D008297:Male; D008334:Mandible / Q000601:surgery*; D008904:Miniaturization; D008963:Molar / Q000000981:diagnostic imaging; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation* / Q000379:methods; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D016348:Osseointegration / Q000502:physiology; D016300:Radiography, Bitewing / Q000379:methods; D011897:Random Allocation; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D014092:Tooth Root / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D003764:Dental Materials; D014025:Titanium