title: Strain of bone-implant interface and insertion torque regarding different miniscrew thread designs using an artificial bone model.
abstract: OBJECTIVE
  To evaluate the initial stability of dual-thread miniscrews by analyzing the strain at the bone-implant interface and insertion torque during implantation in artificial bone models with different cortical bone thicknesses.
  
  
  METHODS
  Insertion torque, and strain, measured with a five-element strain gauge in 1.0, 1.5, and 2.0-mm artificial cortical bone, during insertion of single- (OAS-T1507) and dual-thread (MPlant-U3) type self-drilling miniscrews were assessed.
  
  
  RESULTS
  Both dual- and single-thread miniscrews showed greater than 7790 μstrain for all cortical bone thicknesses, and dual-thread miniscrews reached up to 19580 μstrain in 2.00 m m cortical bone. The strain of dual-thread miniscrews increased with increasing cortical bone thicknesses of 1.0-2.0mm. For single-thread miniscrews, the maximum insertion torque was relatively constant, but maximum insertion torque increased significantly in dual-thread groups with increasing cortical bone thicknesses (P < 0.0001). The maximum insertion torque with all cortical bone thicknesses was significantly lower with single- than dual-thread types (P < 0.0001).
  
  
  CONCLUSIONS
  Self-drilling dual-thread miniscrews provide better initial mechanical stability, but may cause strain over the physiological bone remodelling limit at the bone-implant interface in thick cortical bone layers.
authors.affiliation: *Department of Orthodontics, Institute of Craniofacial Deformity, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Jung-Yul
authors.initials: JY
authors.lastname: Cha
authors.affiliation: *Department of Orthodontics, Institute of Craniofacial Deformity, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Chung-Ju
authors.initials: CJ
authors.lastname: Hwang
authors.affiliation: **Private Practice, Seoul, South Korea.
authors.forename: Sung Hwang
authors.initials: SH
authors.lastname: Kwon
authors.affiliation: ***Department of Oral Biology, Division in Anatomy and Developmental Biology, Research Center for Orofacial Hard Tissue Regeneration and.
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Jung
authors.affiliation: ****Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Kwang-Mahn
authors.initials: KM
authors.lastname: Kim
authors.affiliation: *Department of Orthodontics, Institute of Craniofacial Deformity, College of Dentistry, Yonsei University, Seoul, Korea, yumichael@yuhs.ac.
authors.forename: Hyung Seog
authors.initials: HS
authors.lastname: Yu
mesh_terms: D000497:Alloys; D001696:Biomechanical Phenomena; D001863:Bone Screws; D018786:Bone Substitutes / Q000737:chemistry; D001842:Bone and Bones / Q000033:anatomy & histology; D000069343:Bone-Implant Interface / Q000502:physiology*; D003722:Dental Alloys / Q000737:chemistry; D055119:Elastic Modulus; D006801:Humans; D008904:Miniaturization; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D011140:Polyurethanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019415:Torque
chemical_list: D000497:Alloys; D018786:Bone Substitutes; D003722:Dental Alloys; D011140:Polyurethanes; C031462:titanium alloy (TiAl6V4); D014025:Titanium