title: Orthodontic miniscrews: an experimental campaign on primary stability and bone properties.
abstract: OBJECTIVE
  To evaluate the primary stability of different shaped miniscrews through the acquisition of data regarding maximum insertion torque, pullout force, and a radiodiagnosic evaluation of bone characteristics.
  
  
  METHODS
  Sixty fresh porcine bone samples were scanned by computed tomography (CT) and cone-beam computed tomography (CBCT). By means of a dedicated software, CT and CBCT images were analysed to measure the insertion-site cortical thickness, cortical density, and marrow bone density. Sixty miniscrews of 12 different types were implanted with no predrilling pilot hole in the bone samples. Every device was tightened by means of a digital torque screwdriver and torque data were collected. Subsequently, pullout tests were performed. Spearman and Pearson correlations were employed to compare any relationship between continuous variables.
  
  
  RESULTS
  Different types of miniscrews did not show statistically significant differences in their torque value (P = 0.595), instead a significant difference was revealed by considering their load measures (P = 0.039). Cortical bone thickness resulted strongly correlated both with value of load (P < 0.001), and modestly with torque measures (P = 0.004). A strong positive correlation was found between CT and CBCT both for cortical density (P < 0.001) and marrow bone density (P < 0.001).
  
  
  CONCLUSIONS
  Bone characteristics play the major role in miniscrews primary stability.
authors.affiliation: *Orthodontics Department, Genoa University School of Dentistry, marco.migliorati@unige.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Migliorati
authors.affiliation: *Orthodontics Department, Genoa University School of Dentistry.
authors.forename: Sara
authors.initials: S
authors.lastname: Drago
authors.affiliation: **Section of Biostatistics, Department of Health Sciences (DISSAL), Genoa University.
authors.forename: Irene
authors.initials: I
authors.lastname: Schiavetti
authors.affiliation: *Orthodontics Department, Genoa University School of Dentistry.
authors.forename: Francesco
authors.initials: F
authors.lastname: Olivero
authors.affiliation: ***Department of Civil, Chemical and Environmental Engineering (DICCA), Genoa University, and.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Barberis
authors.affiliation: ***Department of Civil, Chemical and Environmental Engineering (DICCA), Genoa University, and.
authors.forename: Alberto
authors.initials: A
authors.lastname: Lagazzo
authors.affiliation: ***Department of Civil, Chemical and Environmental Engineering (DICCA), Genoa University, and.
authors.forename: Marco
authors.initials: M
authors.lastname: Capurro
authors.affiliation: *Orthodontics Department, Genoa University School of Dentistry.
authors.forename: Armando
authors.initials: A
authors.lastname: Silvestrini-Biavati
authors.affiliation: ****Department of Surgical and Diagnostical Integrated Sciences, Genoa University, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Benedicenti
mesh_terms: D000818:Animals; D015519:Bone Density / Q000502:physiology; D001853:Bone Marrow / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D001863:Bone Screws; D000069343:Bone-Implant Interface / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000379:methods; D003799:Dental Stress Analysis; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D012272:Ribs / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D013314:Stress, Mechanical; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods; D019415:Torque