title: Reliable coupling of orthodontic elements to mini-implants: An in-vitro study.
abstract: OBJECTIVE
  To investigate the reliability of mechanical and adhesive methods of fixing rectangular wires in the cross-slot of a mini-implant.
  
  
  METHODS
  A twin-hooked wire element was placed and fixed in the slot of a mini-implant via a NiTi spring under tension, or by means of an adhesive. For the purpose of mechanical anchorage, the wire was crimped with a special crimping tool to increase its thickness and prevent it from slipping through the slot. Before applying the adhesive, there were four possible methods of preparation: Untreated Wire (Adh. 1); ROCATEC-Pre (Adh. 2); ROCATEC-PRE + Espe Sil (Adh. 3); ROCATEC-PRE + ROCATEC-PLUS + Espe Sil (Adh. 4). The mechanical fixing and two adhesive fixings were aged by means of temperature change (500 cycles). A Zwick universal testing machine was used to measure the maximum strength of the coupling.
  
  
  RESULTS
  In all tests, the untreated wire + adhesive withstood the lowest maximum load (Ø 3 N and 10.8 N respectively) and failed the aging test after a maximum of eight cycles. The wires in test group Adh. 4 withstood the highest maximum load (Ø 43.3 N; 41.5 N; 45.9 N after aging) in all tests. The average load withstood by the crimped ligature was 38.7 N.
  
  
  CONCLUSIONS
  The adhesive method of fixation performs best when the rectangular wire is sand blasted and silanized before application. The mechanical coupling using the crimped ligature is reliable.
authors.affiliation: Department of Orthodontics, University of Homburg / Saar Kirrberger Strasse 1, D- 66421 Homburg / Saar, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Ludwig
authors.affiliation: Department of Prosthodontics, Johann Wolfgang Goethe University Frankfurt, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Zipprich
authors.affiliation: Private Office, Friedhofweg 5, 92676 Eschenbach, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Gebel
authors.affiliation: Department of Orthodontics, Tel Aviv University, Israel.
authors.forename: Ben
authors.initials: B
authors.lastname: Piller
authors.affiliation: Department of Dentofacial Orthopedics and Orthodontics, Wroclaw Medical University, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Antoszewska
keywords: Adhesive; NiTi spring; coupling elements; cross-slot; in-vitro experiment; orthodontic mini-implants; orthodontic wire; rectangular wire