Abstract:
Background For patients with skeletal class III malocclusion due to underdevelopment of maxilla, maxillary protraction is commonly used, but its efficacy at later period of pubertal peak is controversial.
Objective To evaluate the treatment effects of modified maxillary protraction on hard tissue changes in patients with skeletal class Ⅲ malocclusion at later period of pubertal peak using cephalometric measurements.
Methods Patients with skeletal class Ⅲ malocclusion at later period of pubertal peak (CVM Ⅴ-Ⅵ stage) who visited the Department of Orthodontics, the First Medical Center, Chinese PLA General Hospital from 2017 to 2023 were selected. The treatment was carried out using a modified pad intraoral appliance combined with an extraoral double-rod maxillary anterior distractor. Before and after treatment, lateral cephalometric radiographs were taken to measure and analyze the changes of facial bone and dental indices.
Results Of the 26 cases, there were 16 males and 10 females, aged 12-15 years old, and the average course of treatment was 8.2 months. After modified maxillary protraction treatment, the sagittal position indices of maxilla increased significantly, including SNA increased by 2.67° ± 1.29° (P<0.001), ss/OLP increased by (3.91 ± 1.98) mm (P<0.001), Or/OLP increased by (1.57 ± 2.00) mm (P=0.001), and Ptm/OLP increased by (0.64 ± 1.39) mm (P=0.028). The inclination of upper anterior teeth (U1-SN) increased by an average of 1.07°. The inclination of lower anterior teeth (IMPA) decreased by 1.41° ± 4.64°(P=0.133).
Conclusion The application of modified pad intraoral appliance combined with extraoral double-rod maxillary anterior distractor can effectively promote maxillary advancement of patients with skeletal class Ⅲ malocclusion at later period of pubertal peak, and control the lip inclination of upper anterior teeth and the tongue inclination of lower anterior teeth well.