SETTING AND SAMPLE POPULATION: Orthodontic population from the Faculty of Dentistry of the University of Hong Kong.
METHODS: Thirty-four skeletal class II patients treated with the HGA (17 patients, mean age 10.6 ± 1.5 years) and the Herbst (17 patients, mean age 11.0 ± 1.4 years) were matched for sex, age, overjet, skeletal class and mandibular divergence. The patients received lateral cephalometric radiographs (LCRs) at the beginning of treatment (T1 ), after treatment (T2 ) and at follow-up (T3 ). In the HGA group, patients underwent LCRs 7 months before the beginning of treatment (T0 ), which were used as growth reference for intra-group comparison. Paired Student's t tests were used for intra- and inter-group comparisons (α = .05).
RESULTS: Treatment changes (T2 -T1 ) did not differ significantly between the groups. However, at follow-up (T3 -T1 ) the Herbst group showed a smaller increase than the HGA group in the vertical position of the hyoid bone relative to the Frankfort plane (P = .013) and mandibular plane (P = .013).
CONCLUSIONS: There were no significant differences in the upper airway, hyoid bone position and craniofacial morphology between the groups at the end of treatment. However, the Herbst may provide better long-term control of the vertical position of the hyoid bone than the HGA in children with skeletal class II malocclusion.
METHODS: Data consisted of pre- and post-treatment lateral cephalograms of 95 children, 49 patients with RTB and 46 patients with RPFM, divided into an early (8-9 year) and late (10-11 year) group. Treatment changes were assessed by the Ricketts analysis using CASSOS software, where 71 anatomic landmarks were identified in each cephalogram. Paired and independent t tests were performed for statistical comparison.
RESULTS: Paired t test revealed significant changes in facial axis, facial angle, MD plane to FH, lower facial height, mandibular arc, maxillary convexity, U1 to APog, L1 to APog, L1 to APog angle and upper lip to E-plane measurements in RPFM, whereas significant changes were found in facial taper, U1 to APog and lower lip to E-plane values with RTB in the early treatment group. Independent t test revealed significant changes in U1 to APog, L1 to APog and U6 to PtV values in the RTB group. Post-treatment comparison of RTB and RPFM showed significant differences in L1 to APog and L1 to APog angle values.
CONCLUSIONS: RPFM revealed more favourable craniofacial changes than RTB, particularly in the late mixed dentition stage.