拔牙矫治对成人下颌后缩型骨性II类高角患者口咽气道影响的研究

Objective: To explore the effect of premolar extraction on the oropharyngeal airway and the position of the hyoid bone in adult skeletal Class II hyperdivergent patients with mandibular retraction. Methods: Twenty adult patients with skeletal II hyperdivergent with mandibular retraction were selected; CBCT was taken before and after treatment according to the unified standard, and then the data were imported into dolphin software. After three-dimensional head position correction, oropharyngeal airway and lateral cephalogram were reconstructed, the related analysis indexes were measured to analyze and evaluate the changes pre and post treatment. Results: 1. OP, GP, A, AGP, SSP, UTL, Sep, ETL, CSAmin and Lmin decreased significantly after tooth extraction (P < 0.05); VP, APP, SHP, PNSL, UTW, ETW and Wmin decreased, but there was no significant difference (P > 0.05); He1, He2, He3 and PNSW showed an increasing trend, and there was no significant difference (P > 0.05); 2. After tooth extraction, H-FH (VER) representing the vertical position of hyoid bone increased and H-C3la (HOR) representing the horizontal position of hyoid bone decreased, but there was no significant difference (P > 0.05); 3. After tooth extraction, the craniomaxillofacial bone indexes SNA, ANB, MP-FH and MP-SN decreased significantly (P < 0.05), and SNB increased significantly (P < 0.05); The dental indexes U1-FHP, U1-SN, L1-FHP, L1-MP decreased significantly(P < 0.05). Conclusion: 1. The volume of the oropharyngeal airway decreased after orthodontic extraction in adult skeletal Class II hyperdivergent patients with mandibular retraction, which mainly occurs in the sagittal direction, while the coronal and vertical height have no obvious changes; 2. The hyoid bone position did not change significantly after tooth extraction.