女性前牙反(牙合)下颌骨生长发育趋势二维有限元研究--从乳牙期到替牙期

目的用有限元法分析女性前牙反牙合患者从乳牙期到替牙期下颌骨生长发育特征,为前牙反牙合的预防和矫治提供理论参考.方法用专门建立的颅颌面形态有限元分析系统对样本的头颅侧位定位片进行二维有限元分析.结果从乳牙期到替牙期,下颌骨所有单元的Emax均为拉应变,除单元13外,其余单元面积均有不同程度增加,以颏前下部面积增加最多,且有一定的逆时针旋转,可能对骨性下颌前突起一定作用.下颌骨升支和体部的生长呈多向性,在面积增加的同时,旋转方向也各不相同,形状也发生了一定变化,但下颌骨整体形态尚未受到明显影响.结论女性前牙反牙合患者下颌骨贒-M期生长发育过程中,各单元在生长变大的同时,形状也在发生不同程度的变化,以颏前下部变化最为明显.但下颌骨整体形态尚未受到明显影响.因此,前牙反牙合应早期矫治,以阻断那些异常的生长方式,引导其恢复到正常的生长方式.

Two dimensional finite element analysis of development tendency of mandible of female with anterior cross bite-from decieuous dentition period to mixed dentition period

Objective To analyze the growth and development characteristics of mandibles of patients with anterior crossbite from deciduous dentition period to mixed dentition period, and apply theoretic references for the prevention and treatment of anterior crossbite.Method A special developed finite element analysis computer system for cranialfacial morphology was used to perform two-dimensional!analysis of lateral cephelogram of the sample. Results From deciduous dentition period to mixed dentition period, the maximum strains (Emax) of all the elements of the mandible were tension strain. The area of all the elements increased except for element 13.The most outstanding increase of area occurred in the anterior and lower component of the chin with counterclockwise rotation to some extent, which may contribute to the skeletal protrusion of the mandible. The growth of the ramus and body of mandible was politropism, which showed change of shape to some extent, different direction of rotation as well as increase of the area. Conclusion From deciduous dentition period to mixed dentition period, all the elements of the mandible of the female patients with crossbite showed change of shape to some extent as well as growth in size. The anterior and lower component of the chin changed mostly. Thus anterior crossbite should be treated earlier, in order to interrupt those abnormal growth pattern, and to restore the normal growth pattern.