Effects of molar distalization with the fast back appliance

Int J Orthod Milwaukee. 2013 Winter;24(4):25-31.


Few studies had investigated the effectiveness of the Fast Back appliance. As a result of that, this study was concerned about evaluating the dental and skeletal effects of the Fast Back appliance used in distalization of maxillary first molars.

Materials and methods: The sample was consisted of 14 female patients. However, four of them discontinued the treatment due to different causes. As a result of this, the study was performed on 10 female patients, with their age ranged from 11-13 years. All patients had skeletal Class I, space deficiency in the upper arch less than 8 mm, and non-extraction lower arch. Distalization using the Fast Back appliance was started at the beginning of the treatment and continued until an overcorrected Class I molar relation was achieved. Lateral cephalometric radiographs and dental casts were obtained before and immediately after distalization, and statistical evaluation of the variables measured on them were done.

Results: The maxillary first molars were distalized into an overcorrected Class I in a mean duration of 3.8 months. They were distalized significantly according to cephalometric measurements and dental cast measurements (3.4 +/- 0.71 and 3.69 +/- 1.51 mm respectively) (p< .05), with a significant distal tipping about 3.55 degrees +/- 3.95 degrees and a significant increase in intermolar width by 3.55 +/- 2.58 mm (p< .05). However, the vertical positions of the upper first molars were insignificantly changed (p>. 05), and rotations of these teeth were negligible (p>. 05). Loss of anchorage was evidenced by the significant mesial movements of the upper first premolars. They were significantly tipped mesially, rotated, and extruded (p< .05). On the other hand, the interpremolar distance was insignificantly changed. The overjet was significantly increased and the overbite was significantly decreased. The skeletal changes sagitally and vertically were insignificant, except for the increase in mandibular plane angle (FMA angle) which was signficant.

Conclusions: The Fast Back is an efficient noncompliance appliance to distalize molars without rotations. However, these movements are associated with distal molar tipping and anchorage loss of the anterior teeth.

MeSH terms

  • Adolescent
  • Bicuspid / pathology
  • Cephalometry / methods
  • Child
  • Dental Arch / pathology
  • Female
  • Humans
  • Incisor / pathology
  • Malocclusion, Angle Class I / therapy
  • Maxilla / pathology
  • Models, Dental
  • Molar / pathology*
  • Orthodontic Anchorage Procedures / methods
  • Orthodontic Appliance Design*
  • Overbite / therapy
  • Rotation
  • Tooth Movement Techniques / instrumentation*