title: Bone density and miniscrew stability in orthodontic patients.
abstract: OBJECTIVE
  The purpose of this study was to evaluate bone density in buccal inter-radicular bone between second premolars and first permanent molars and its association with the clinical stability of miniscrews used for en masse retraction of anterior teeth in extraction cases.
  
  
  METHODS
  Thirty-eight miniscrews were placed in ten patients (8 females, 2 males: mean age, 18.9 +/- 4.12 years) to provide indirect orthodontic anchorage. Twenty miniscrews were placed in the maxilla and eighteen were inserted in the mandible. All of the miniscrews were placed in the buccal inter-radicular bone between the second premolar and the first permanent molar. Bone density at each miniscrew site was recorded by computed tomography and recorded in Hounsfield units (HU) before miniscrew placement. Nickel-titanium closed-coil springs were used to apply an orthodonticforce of 2N within one week following placement.
  
  
  RESULTS
  Cortical bone density values ranged from 506.7- 1705.6 HU (Mean, 929.27 +/- 322.12 HU) in the maxilla and 503.8 - 1544.8 HU (Mean, 1116.2 +/- 298.33 HU) in the mandible. Cancellous bone density values ranged from 185.9 - 930.8 HU (Mean, 450.09 +/- 205.66 HU) in the maxilla and 197.3 - 803.6 HU (Mean, 561.87 +/- 170.83 HU) in the mandible. There was no statistically significant difference between right and left sides. A bone density comparison between the maxilla and mandible revealed statistically significant higher values in mandibular cortical bone (p = 0.008), while no significant difference was found in cancellous bone values (p = 0.097). Clinically, the success rate of miniscrews in the maxilla was 100% but only 77.8% in the mandible. Miniscrew failures were associated with peri-implant inflammation and miniscrew proximity to dental roots. No relation was found between bone density and miniscrew stability.
  
  
  CONCLUSIONS
  The present study determined that no definitive association could be established between miniscrew success and bone density.
authors.affiliation: Division of Orthodontics and Dentofacial Deformities, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Vilas
authors.initials: V
authors.lastname: Samrit
authors.forename: Om Prakash
authors.initials: OP
authors.lastname: Kharbanda
authors.forename: Ritu
authors.initials: R
authors.lastname: Duggal
authors.forename: Ashu
authors.initials: A
authors.lastname: Seith
authors.forename: Varun
authors.initials: V
authors.lastname: Malhotra
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid; D015519:Bone Density / Q000502:physiology*; D001863:Bone Screws / Q000009:adverse effects; D003722:Dental Alloys / Q000737:chemistry; D003724:Dental Arch / Q000033:anatomy & histology*; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy; D008312:Malocclusion, Angle Class II / Q000628:therapy; D008334:Mandible / Q000033:anatomy & histology; D008437:Maxilla / Q000033:anatomy & histology; D008963:Molar; D061330:Multidetector Computed Tomography; D009532:Nickel / Q000737:chemistry; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D019516:Orthodontic Space Closure / Q000295:instrumentation; D009969:Orthodontic Wires; D010147:Pain Measurement; D010518:Periodontitis / Q000209:etiology; D014025:Titanium / Q000737:chemistry; D055815:Young Adult
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium