Longitudinal study of anteroposterior and vertical maxillary changes in skeletal class II patients treated with Kloehn cervical headgear.

This is a study to evaluate the posttreatment and long-term anteroposterior and vertical maxillary changes in skeletal Class II Division 1 patients (ANB > or = 5 degrees) who had received Kloehn cervical headgear treatment. The sample consisted of 120 lateral cephalograms obtained at pretreatment (T1), posttreatment (T2), and postretention (T3) phases of 40 patients (18 males and 22 females). The patients were of an average age of 10% years in phase T1, 13% years in phase T2, and 23% years in phase T3. They were treated with cervical traction and an expanded inner bow (4-8 mm) and a long outer bow bent upwards off the horizontal 10-20 degrees in relation to the inner bow. After correction of the molar relationship on both sides, a conventional edgewise fixed appliance was used to complement the correction of the malocclusion. The onset of treatment was either at the late mixed dentition or at the beginning of the permanent dentition. The force applied for the 40 patients averaged 450 g and the recommended use of the appliance was 12-14 hours per day with monthly adjustments. F-Snedecor test was applied to the entire sample and multiple comparisons between phases were tested by the Bonferroni method. Results revealed that treatment had reduced maxillary protrusion, inclined the palatal plane with an increase in the SN-PP angle with reduction at long-term. In conclusion, Kloehn cervical headgear with elevated external bow and expanded inner bow was efficient in correcting the skeletal Class II in late mixed-early permanent dentition. Skeletal Class II correction with Kloehn cervical headgear was found to be very stable long term.