目的：利用Johnston分析法评价Tweed-Merrifield技术矫治双颌严重前突成人患者牙性及骨性变化对治疗结果的影响。方法：应用回顾性自身对照方法，对12 例采用Tweed-Merrifield拔牙技术矫治的双颌前突成人患者采用Johnston分析法和华正测量软件对常规测量项目进行矫治前后的X线头影测量对比分析。结果：矢状方向上，上颌骨相对颅底后移1.30 mm，下颌骨相对颅底前移2.12 mm，上下颌骨相对位置变化了3.42 mm；上下切牙均明显后移并直立，上下磨牙略前移，矫治后磨牙关系及前牙覆盖分别改变了3.44 mm和4.23 mm。ANB、U1NA、U1/NA、U1/SN、L1NB、L1/NB、L1/MP值治疗后分别改变 －(1.98±1.55)°（P=0.012）、－(5.08±4.6) mm（P=0.002）、－(11.79±1.21)°（P=0.004）、－(13.55±6.32)°（P=0.047）、－(3.17±3.07) mm（P=0.010）、 －(6.84±2.55)°（P=0.038）、－(4.13±2.24)°（P=0.048)，差异均有统计学意义。结论：TweedMerrifield技术通过定向力系统的施行，可以稳定支抗磨牙，内收前牙，显著改善双颌前突患者的软硬组织侧貌，且实现了较好的垂直向控制，适用于需要强支抗的双颌前突患者的拔牙矫治。

Objective： To evaluate the influence of Tweed-Merrifield technique in correction of severe bimaxillary protrusion adult patients on the measurement of the dental and skeletal changes after orthodontic treatment by Johnston analysis and the regular cephalomatric analysis. Methods: Twelve adolescent patients with severe bimaxillary protrusion were included in this self-control retrospective study. Lateral cephalometric radiographs were taken before and after treatments. All the radiographs were traced and analyzed by the method of Johnston analysis. Other measurements were evaluated using a series of 13 linear and angular measurements including SNA, SNB, ANB, U1-SN, U1-NA, U1/NA, L1-NB, U1/NB, L1/MP, U1-L1, (U1+L1)/2-AB, MP/SN and MP/FH from regular cephalomatric analysis. These measurements were also applied to compare the differences between pre-and post-treatments, which clarify the dental and skeletal changes by Johnston analysis. The effect of orthodontic correction was determined using the non-parameters test. Results: The maxillary moved backforward by 1.3 mm according to the stable skull base, while the mandible moved forward by 2.12 mm. The relative position between the maxillary and mandible (ABCH) changed 3.42 mm. The upper and lower incisors retracted significantly. The upper and lower molars moved slightly forward and the relative positions of upper and lower molars and anterior teeth after treatment were 3.44 mm and 4.23 mm respectively. After treatment, the parameters of ANB、U1NA、U1/NA、U1SN、L1NB、L1/NB and L1-M were reduced by -(1.98±1.55)°(P=0.012), -(5.08±4.6) mm (P=0.002), -(11.79±1.21)°(P=0.004), -(13.55±6.32)°(P=0.047), -(3.17±3.07) mm (P=0.010), -(6.84±2.55)°(P=0.038) and -(4.13±2.24)°(P=0.048) on average, whose changes had the statistically significant effects. Conclusion: Tweed-Merrifield technique (directional force technique) can stabilize anchorage molar, retract anterior teeth and significantly improve the hard and soft tissue profile for patients with bimaxillary protrusion, and make a good vertical control which means this technique is applicable to the patients who need strong anchorage. Even for the severe bimaxillary protrusion adult patients, the Tweed-Merrifield technique can control the anchoragewell and make the profiles improved greatly.