Maxillary molar distalization: Pendulum and Fast-Back, comparison between two approaches for Class II malocclusion

Prog Orthod. 2011;12(1):8-16. doi: 10.1016/j.pio.2011.02.007. Epub 2011 Mar 31.


Objectives: To compare the dento-alveolar and skeletal effects produced by two different molar intraoral distalization appliances, Pendulum and Fast-Back, both followed by fixed appliances, in the treatment of Class II malocclusion.

Materials and methods: 41 patients for Pendulum (18 males and 23 females) and 35 for Fast-Back (14 males and 21 females) were selected, with a mean age at the start of treatment of 12.11 years in the Pendulum group and 13.3 for in the Fast-Back group. The durations of the distalization phase were 8 months in the Pendulum group and 9 months in the Fast-Back group, and the durations of the second phase of treatment with fixed appliances were 19 months in the Pendulum group and 20 months in the Fast-Back group. Lateral cephalograms were analyzed at 3 observation times: before treatment, after distalization and after comprehensive orthodontic treatment.

Results: During molar distalization the Pendulum subjects showed greater distal molar movement and less anchorage loss at both the premolars and maxillary incisors than the Fast-Back subjects. Pendulum and Fast-Back produced similar amounts of distal molar movement and overcorrection of molar relationship at the end of distalization though the Fast-Back induced a more bodily movement. Very little change occurred in the inclination of the mandibular plane at the end of the 2-phase treatment in both groups. At the end of treatment the maxillary first molars were on average 1mm more distal in the Pendulum group compared to the Fast-Back group, while the total molar correction was 3.2mm with 3.9° of distal inclination for the Pendulum and 2mm with 1.1° of mesial inclination for the Fast-Back. Both appliance were equally effective in inducing a satisfactory Class I relationship in 97.2% of the cases.

Conclusion: The Pendulum and the Fast-Back induce similar dentoskeletal effects. The use of the two distalization devices, therefore, can be considered clinically equivalent.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Adolescent
  • Cephalometry
  • Child
  • Female
  • Humans
  • Male
  • Malocclusion, Angle Class II / therapy*
  • Maxilla
  • Molar
  • Orthodontic Appliances*
  • Retrospective Studies
  • Tooth Movement Techniques / instrumentation*