title: Different bracket-archwire combinations for simulated correction of two-dimensional tooth malalignment: Leveling outcomes and initial force systems.
abstract: OBJECTIVE
  Self-ligating brackets are widely believed to be more effective in clinical use and to involve less friction and force. Thus, the goal of this in vitro investigation was to experimentally assess the effectiveness of different bracket-archwire combinations and the force levels exerted in two-dimensional direction during correction of tooth malalignment. An important aspect of this objective was to determine whether the behaviors of conventional bracket systems with an elastic or steel ligature differ from that of self-ligating brackets.
  
  
  METHODS
  Three conventional (Mini Taurus®, RMO; Synergy®, RMO; Victory Series™, 3M Unitek) and three self-ligating bracket systems (Speed™, Strite; Smart Clip™, 3M Unitek; Time 3, American Orthodontics) were analyzed. All brackets had 0.018-inch (0.46-mm) slots and--except for the self-ligating brackets-were tested with both a steel ligature (0.25 mm; Remanium, Dentaurum) and an elastic rubber ligature (1.3 mm in diameter; Dentalastics, Dentaurum). They were fitted with four different round wires: a 0.30-mm stainless steel (3M Unitek), 0.38-mm stainless steel coaxial (Advanced Orthodontics), 0.30-mm Thermalloy NiTi (RMO), and 0.30-mm Orthonol NiTi (RMO) archwire. The orthodontic measurement and simulation system (OMSS) was used to simulate a two-dimensional (2 mm of infraocclusion and 2 mm of vestibular displacement) malalignment of tooth 21 inserted in a resin replica of a Frasaco model. Four brackets of the same type were assessed and four individual measurements taken per bracket to analyze initial force systems and corrective malalignment outcomes.
  
  
  RESULTS
  The initial force systems and tooth movements varied distinctly between the different material combinations in conjunction with the ligation systems and archwire types used. The force systems generated were readily reproducible across individual measurements. Leveling outcomes and force systems between conventional steel-ligated and self-ligating brackets coincided in most cases. Both of these device configurations corrected the malalignment by 78-99 % on average. Rubber-ligated conventional brackets, by contrast, performed significantly worse due to exertion of significantly higher forces and 60 % less of a leveling effect.
  
  
  CONCLUSIONS
  Our investigation demonstrates that both conventional steel-ligated brackets and self-ligating brackets, which are highlighted in the literature as highly efficient systems, lead to equivalent corrective outcomes in the treatment of tooth malalignments.
authors.affiliation: Oral Medical Technology, Friedrich-Wilhelm University of Bonn, Welschnonnenstr. 17, 53111, Bonn, Germany.
authors.forename: Sue
authors.initials: S
authors.lastname: Holtmann
authors.forename: Anna
authors.initials: A
authors.lastname: Konermann
authors.forename: Ludger
authors.initials: L
authors.lastname: Keilig
authors.forename: Susanne
authors.initials: S
authors.lastname: Reimann
authors.forename: Andreas
authors.initials: A
authors.lastname: Jäger
authors.forename: Mona
authors.initials: M
authors.lastname: Montasser
authors.forename: Tarek
authors.initials: T
authors.lastname: El-Bialy
authors.forename: Christoph
authors.initials: C
authors.lastname: Bourauel
mesh_terms: D003131:Combined Modality Therapy / Q000295:instrumentation / Q000379:methods; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods; D019544:Equipment Failure Analysis; D006801:Humans; D008310:Malocclusion / Q000503:physiopathology* / Q000628:therapy*; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013314:Stress, Mechanical; D014071:Tooth Abnormalities / Q000503:physiopathology* / Q000628:therapy*; D014087:Tooth Movement Techniques / Q000295:instrumentation* / Q000379:methods; D016896:Treatment Outcome