title: Three-dimensional analysis of the distal movement of maxillary 1st molars in patients fitted with mini-implant-aided trans-palatal arches.
abstract: OBJECTIVE
  The aim of this study was to investigate three-dimensional molar displacement after distalization via miniscrews and a horizontal modification of the trans-palatal-arch (TPA).
  
  
  METHODS
  The subjects in this clinical trial were 26 Class II patients. After the preparation of a complete set of diagnostic records, miniscrews were inserted between the maxillary 2nd premolar and 1st molar on the palatal side. Elastic modules connected to the TPA exerting an average force of 150-200 g/side parallel to the occlusal plane were applied. Cone-beam computed tomography was utilized to evaluate the position of the miniscrews relative to the adjacent teeth and maxillary sinus, and the direction of force relative to molar furcation. The distances from the central point of the incisive papilla to the mesiopalatal cusps of the 1st maxillary molars and the distances between the mesiopalatal cusps of the left and right molars were measured to evaluate displacement of the maxillary molars on the horizontal plane. Interocclusal space was used to evaluate vertical changes.
  
  
  RESULTS
  Mean maxillary 1st molar distalization was 2.3 ± 1.1 mm, at a rate of 0.4 ± 0.2 mm/month, and rotation was not significant. Intermolar width increased by 2.9 ± 1.8 mm. Molars were intruded relative to the neighboring teeth, from 0.1 to 0.8 mm.
  
  
  CONCLUSIONS
  Distalization of molars was possible without extrusion, using the appliance investigated. The intrusive component of force reduced the rate of distal movement.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran. ; Hamadan Dental Research Centre, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Amirfarhang
authors.initials: A
authors.lastname: Miresmaeili
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Sajedi
authors.affiliation: Department of Biostatistics, Faculty of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Moghimbeigi
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Farhadian
keywords: Dental models; Orthodontic anchorage procedures; Tooth movement