Transverse stability of Class II malocclusion correction with the pendulum appliance.

Introduction: This study aimed to evaluate the stability of transverse changes after Class II malocclusion correction with the pendulum fixed distalizer, followed by preadjusted edgewise fixed orthodontic appliances.

Methods: This longitudinal study was conducted in the maxillary dental casts of 20 Class II malocclusion subjects (mean age, 12.5 years; 14 females and 6 males). Eighty 3-dimensional maxillary dental casts were analyzed; 20 at the beginning of treatment, 20 after distalization, 20 after edgewise appliance debonding, and 20 at 5 years posttreatment. Maxillary transverse distances between canines, first premolars, second premolars, first molars, and second molars were analyzed using Geomagic Studio 5 (3D Systems, Rock Hill, SC).

Results: There were no significant changes in intercanine distance during and after treatment. There were significant interfirst and intersecond premolar distance increases during treatment. There were significant interfirst and intersecond molar distance increases during the distalization phase. However, there were significant decreases in these distances at the end of treatment. There were no significant long-term posttreatment changes.

Conclusions: The intercanine distance remains stable during and after treatment. The interfirst and intersecond premolar distances significantly increase during treatment and remain stable after treatment. The interfirst and intersecond molar distances increase during the distalization phase, decrease at the end of treatment, and remain stable after treatment.