title: Optimal asymmetric thread for orthodontic microimplants: Laboratory and clinical evaluation.
abstract: OBJECTIVE
  To investigate the performance of microimplants incorporating a newly designed asymmetric thread.
  
  
  METHODS
  Three microimplants were compared. The control group comprised microimplants with the original v-shaped thread. The two experimental groups (Taper 1.0 and Taper 1.25) comprised prototype microimplants constructed with the new asymmetric thread; the Taper 1.25 specimens had a 1.25-mm-long and sharper tip, while the Taper 1.0 and control groups had a less sharp 1-mm tip. Two specially designed artificial bone blocks mimicking soft (maxillary) and hard (mandibular) bone were used to evaluate the microimplant insertion characteristics and postinsertion lateral stability. The peak insertion torque, insertion time, Periotest value (PTV), and torsional strength were measured. Then the microimplants were evaluated clinically over a 3-month period.
  
  
  RESULTS
  Significant differences in peak insertion torque, insertion time, and PTV were observed and favored the experimental groups. Although statistically insignificant, the clinical success rate was also higher in the Taper 1.25 experimental group than in the control group (87.2% vs 75.6%).
  
  
  CONCLUSIONS
  The better performances of the experimental microimplant, under both laboratory and clinical conditions (although statistically insignificant in the latter), demonstrate the superiority of the new asymmetric thread.
authors.affiliation: a  Former Research Assistant, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Raed H
authors.initials: RH
authors.lastname: Alrbata
authors.affiliation: b  Orthodontist, Mir Dental Hospital, Daegu, Korea.
authors.forename: Do-Won
authors.initials: DW
authors.lastname: Ha
authors.affiliation: c  Associate Professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Wonjae
authors.initials: W
authors.lastname: Yu
authors.affiliation: d  Professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Hee-Moon
authors.initials: HM
authors.lastname: Kyung
mesh_terms: D000071556:Cancellous Bone / Q000033:anatomy & histology; D016022:Case-Control Studies; D000071538:Cortical Bone / Q000033:anatomy & histology; D015921:Dental Implants; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology; D008422:Materials Testing; D008437:Maxilla / Q000033:anatomy & histology; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D019415:Torque; D054159:Torsion, Mechanical; D014732:Vibration; D055815:Young Adult
chemical_list: D015921:Dental Implants
keywords: Asymmetric thread; Clinical test; Lab test; Orthodontic microimplant