title: Second order root control of self-ligating brackets and traditional brackets: a "typodont" study.
abstract: OBJECTIVE
  Aim of the study was to evaluate if self-ligating brackets (SLB) and conventional brackets (CB) have the same degree of second order root control in closing extraction spaces.
  
  
  METHODS
  Two resin models, left and right sides of an upper arch, with two wells in the premolar area, were used. Wells have been filled with wax and resin premolars with anatomic root structure were placed in them. Resin premolars were bonded with CB and SLB. We performed 20 pairwise runs: CB on one side against SLB on the other side. We tested 0.018 and 0.016x0.022 stainless steel arches. Models were put in warm water to allow teeth to move in the softened wax by the force excerpted by NiTi coils. Root control in the second order was evaluated with the aid of metallic markers on the roots and digital radiographies taken before and after each run.
  
  
  RESULTS
  On 0.018 wires CB moved 4.0 mm (SD 1.06 mm), mean root control angle was 14.8° (SD 9.15°), while SLB moved 4.1 mm (SD 1.33 mm), mean angle in the second order was 11.8° (SD 5.01°). On 0.016x0.022 wires CB moved 3.6 mm (SD 1.24 mm), mean angle in the second order was 9.7° (SD 5.48°) while SLB moved 3.4 mm (SD 1.05 mm), mean angle was 10.7° (SD 3.92°).
  
  
  CONCLUSIONS
  It seems that, on typodont, CB and SLB are equally efficient in moving teeth crowns and have the same degree of second order root control, both when 0.018 and 0.016x0.022 stainless steel wires are used.
authors.affiliation: Oral Rehabilitation Unit, Department of Biomedical, Surgical and Dental Science, Istituto Stomatologico Italiano University of Milan, Milan, Italy - acbutti@gmail.com.
authors.forename: A C
authors.initials: AC
authors.lastname: Butti
authors.forename: R
authors.initials: R
authors.lastname: Mangiacapra
authors.forename: I
authors.initials: I
authors.lastname: Saporito
authors.forename: G
authors.initials: G
authors.lastname: Augusti
authors.forename: A
authors.initials: A
authors.lastname: Salvato
authors.forename: D
authors.initials: D
authors.lastname: Re
mesh_terms: D001641:Bicuspid; D004867:Equipment Design; D066298:In Vitro Techniques; D008953:Models, Anatomic; D016910:Orthodontic Brackets; D019252:Radiography, Dental, Digital; D012117:Resins, Synthetic; D014092:Tooth Root; D014885:Waxes
chemical_list: D012117:Resins, Synthetic; D014885:Waxes