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目的:建立并使用上颌发育不足三维有限元模型,研究不同前方牵引方向对颅上颌复合体的影响,以期为上颌前方牵引的临床应用提供理论依据。方法:选择1名9岁上颌骨发育不足女性志愿者,采用螺旋CT扫描、数据传输与转录、Mimics10.0软件建立颅上颌复合体的三维有限元模型,利用ANSYS10.0软件,在上颌尖牙处施加与水平面呈-20°～50°的前方牵引力,大小为5N,分析颅上颌复合体的位移变化和内部应力分布。结果:垂直方向上,当牵引角度为-20°～30°时,颅上颌复合体呈逆时针旋转,且随着角度的增加而减小;30°～40°时,垂直向位移为零;≥40°时,颅上颌复合体顺时针旋转,且随角度的增加而增加。水平方向上,牵引角度在-20°～50°时,颅上颌复合体前移,且随着角度增加而减小;0°位移最大。近中方向上:颅上颌复合体及上颌牙弓有向近中位移的趋势,且随牵引角度增大而减小。随着角度的增大,最大主应力呈现递增趋势,范式应力先减后增;当牵引角度大于10°时,最大主应力和范式应力均递增,且递增速度较快。结论:当上颌前方牵引角度与水平面呈30°～40°时,颅上颌复合体平动;大于此范围,可能出现深覆,反之有开的风险。牵引角度越大,颅上颌复合体前移量越小,应力越大。
OBJECTIVE: To establish and use the three-dimensional finite element model of maxillary hypoplasia to study the influence of different anterior traction directions on cranial maxillary complex in order to provide a theoretical basis for the clinical application of maxillary anterior traction. Methods: A 9-year-old female with mandibular hypoplasia was selected. Three-dimensional finite element model of cranial maxillary complex was established by using spiral CT scan, data transmission and transcription. Mimics 10.0 software was used to establish the maxillary canine maxillary complex. Using ANSYS 10.0 software, At the level of -20 ° ~ 50 ° applied front traction, the size of 5N, analysis of the cranial maxillary complex displacement changes and internal stress distribution. Results: In the vertical direction, when the traction angle was -20 ° ~ 30 °, the cranial maxilla complex turned counterclockwise and decreased with the increase of the angle. The vertical displacement was zero at 30 ° ~ 40 °. At 40 °, the cranial maxilla complex rotates clockwise and increases with increasing angle. In the horizontal direction, the cranial maxillary complex moved forward when the traction angle ranged from -20 ° to 50 °, and decreased with the increase of the angle. The maximum displacement occurred at 0 °. In the proximal direction, there is a tendency for the craniomaxillary complex and maxillary dental arch to shift in the direction of mid-to-middle and decrease with the increase of traction angle. With the increase of the angle, the maximum principal stress shows an increasing trend, and the normal stress decreases first and then increases. When the traction angle is greater than 10 °, the maximum principal stress and the normal stress increase with increasing speed. CONCLUSIONS: When maxillary traction angle is 30 ° ~ 40 ° with the horizontal plane, cranial maxilla complex translates; above this range, there may be a risk of deep overburns, and vice versa. Larger traction angle, cranial maxillary complex forward shift the smaller, the greater the stress.