title: Bone mineral density.
abstract: OBJECTIVE
  To verify whether bone mineral density (BMD) of cortical bone, trabecular bone, and total bone influence the primary stability of orthodontic miniscrews and to verify whether there is a correlation between the measurement of BMD by cone-beam computed tomography (CBCT) and central dual-energy x-ray absorptiometry (DEXA).
  
  
  METHODS
  Twenty bovine bone sections were extracted from the pubic and iliac bones from regions with cortical thicknesses of approximately 1 mm. The BMD of the total bone block was evaluated using two methods: CBCT and DEXA. The BMD of cortical, trabecular, and total bone in the region of interest (ROI) were also evaluated by CBCT. After scanning the bone blocks, 20 self-drilling miniscrews (INP®) 1.4 mm in diameter and 6 mm long were inserted into them. The peak implant insertion torque (IT) was registered. After this, the pull-out test (PS) was performed and the maximum force registered. The Pearson correlation test was applied to verify the correlations between variables.
  
  
  RESULTS
  The BMD of the total bone block verified by CBCT and DEXA showed a positive and strong correlation (r  =  0.866, P  =  .000). The BMD of the ROI for cortical bone influenced the IT (r  =  0.518, P  =  .40) and the PS of miniscrews (r  =  0.713, P  =  .001, Table 2). However, the total bone BMD (verified by CBCT and DEXA) and trabecular bone BMD presented weak and not statistically significant correlations with primary stability.
  
  
  CONCLUSIONS
  There was a positive correlation between total bone block BMD measured by DEXA and CBCT. The cortical BMD influenced the IT and PS.
authors.affiliation: Pediatric Dentistry and Orthodontics Department, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. marianamarquezan@gmail.com
authors.forename: Mariana
authors.initials: M
authors.lastname: Marquezan
authors.forename: Thiago Chon Leon
authors.initials: TC
authors.lastname: Lau
authors.forename: Claudia Trindade
authors.initials: CT
authors.lastname: Mattos
authors.forename: Amanda Carneiro da
authors.initials: AC
authors.lastname: Cunha
authors.forename: Lincoln Issamu
authors.initials: LI
authors.lastname: Nojima
authors.forename: Eduardo Franzotti
authors.initials: EF
authors.lastname: Sant'Anna
authors.forename: Margareth Maria Gomes de
authors.initials: MM
authors.lastname: Souza
authors.forename: Mônica Tirre de Souza
authors.initials: MT
authors.lastname: Araújo
mesh_terms: D015502:Absorptiometry, Photon; D000818:Animals; D015519:Bone Density; D001863:Bone Screws; D002417:Cattle; D054893:Cone-Beam Computed Tomography; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D020878:Device Removal; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D018709:Statistics, Nonparametric; D019415:Torque
chemical_list: D015921:Dental Implants