Cephalometric evaluation of the effects of pendulum appliance on various vertical growth patterns and of the changes during short-term stabilization.

The aim of this study was to evaluate the effects of the pendulum appliance in dental Class II patients with varying vertical growth patterns and to evaluate the changes during the short-term stabilization period of 3 months. The sample (n=30) was divided into two groups based on their FMA degrees. The high-angle group consisted of 14 patients (10 girls and 4 boys) and had a mean age of 157.7+/-8.0 months. The low-angle group consisted of 16 patients (8 girls and 8 boys) and had a mean age of 155.5+/-18.6 months. Pretreatment, posttreatment and poststabilization cephalometric radiographs were obtained to measure the changes. Mann-Whitney U and Wilcoxon tests were used for statistical evaluation. The amount of upper molar distalization was 5.9 mm (p<0.001) in the high-angle group and 1 mm (p<0.001) in the low-angle group, showing no intergroup difference. The amount of anchorage loss at the second premolars was 4.8 mm (p<0.001) in the high-angle group and 6.6 mm (p<0.001) in the low-angle group. Upper incisors moved anteriorly for 2.1 mm (p<0.05) in the high-angle group and 4.1 mm (p<0.001) in the low-angle group. Intergroup difference was statistically significant (p<0.001). During the stabilization period, 1.5 mm of anchorage loss was measured at the upper molar region in the high-angle group and 1.7 mm of anchorage loss was measured at the upper molar region in the low-angle group. During the stabilization period, upper second premolars and incisors tended to move back to their original places. The results of this study showed that pendulum appliance could move the upper molars distally in a short period of time without depending on the patient compliance. Care should be taken to prevent anchorage loss and to stabilize the upper molars for, at least, 3 months.