da Silva Filho O G, Boas M C, Capelozza Filho L
University of São Paulo, Brazil.
Am J Orthod Dentofacial Orthop. 1991 Aug;100(2):171-9. doi: 10.1016/s0889-5406(05)81524-0.
The present study evaluated the skeletal alterations induced by rapid maxillary expansion procedures in 30 patients in the primary and mixed dentitions. The results were obtained with the use of lateral cephalometrics before and immediately after the active phase of expansion. The time span between these two cephalometric films ranged from 14 to 21 days; therefore the "growth factor" was not considered. Based on the differences in the cephalometric measurements studied on the first and second tracings, it seems that anterior displacement of the maxilla with significant changes in the SNA angle should not be expected, although point B was repositioned more posteriorly (SNB) because of the mandibular downward and backward rotation, with subsequent increase of the inclination of the mandibular plane. The alterations in the A-P position of the mandible was reflected in the increase of ANB and NAP angles. The maxilla always dislocates downward, displaying a downward and backward rotation in the palatine plane, significantly altering the following measurements: N-ANS, PNS-PNS', A-A', SN.PP. The anchoring molars also follow the downward maxillary displacement (M-M') and, as a direct consequence of the vertical displacement of the maxilla and upper molars (N-ANS, A-A', ANS-Me, N-Me, PNS-PNS'), the facial heights increase.
本研究评估了30例处于乳牙列和混合牙列期患者经快速上颌扩弓治疗后引起的骨骼改变。通过在扩弓活跃期开始前及结束后立即拍摄头颅侧位片得出结果。这两张头颅侧位片之间的时间间隔为14至21天；因此未考虑“生长因素”。根据在第一次和第二次描记时所研究的头颅测量值的差异，似乎不应预期上颌会向前移位且SNA角会有显著变化，尽管由于下颌向下和向后旋转，B点位置更向后移（SNB），随后下颌平面倾斜度增加。下颌前后位置的改变反映在ANB和NAP角增大。上颌总是向下移位，在腭平面呈现向下和向后旋转，显著改变了以下测量值：N-ANS、PNS-PNS'、A-A'、SN.PP。支抗磨牙也随上颌向下移位（M-M'），并且由于上颌和上颌磨牙的垂直移位（N-ANS、A-A'、ANS-Me、N-Me、PNS-PNS'），面部高度增加。
