Qin Yan-jun, Shen Yun-juan, Gu Yan, Wang Shan, Liu Ke, Zhao Chun-yang
Department of Orthodontics, Changzhou Stomatological Hospital. Changzhou 213003;Jiangsu Province, China.E-mail:
Shanghai Kou Qiang Yi Xue. 2014 Dec;23(6):699-703.
To study the three-dimensional mechanism of maxillary protraction in skeletal Class III malocclusion by cone-beam CT (CBCT).
Fourteen patients (6 males and 8 females with a mean age of 10.9 years) of early permanent dentition with skeletal Class III malocclusion were treated with maxillary protraction. CBCT was used to obtain the Dicom data both before and after treatment, and then digitized with the software Dolphin 11.0 was used to reconstruct and establish the tridimensional coordinate system. 23 landmarks were chosen for measurement and analysis. The data was analyzed using SPSS 17.0 software package.
After maxillary protraction, A- coronal plane distance, SNA and ANB increased significantly (P<0.01); A- horizontal plane distance, ANS-PNS increased significantly (P<0.05), suggest maxillary growth was forward and downward. Po-S-N increased significantly (P<0.01), while SNB decreased significantly (P<0.05), suggesting that the chin was rotated downward and backward, and mandibular growth was inhibited. U1j - the coronal plane distance increased significantly (P<0.01), suggesting that the upper incisor moved forward; U1-SN angle increased significantly (P<0.05), suggesting anterior teeth inclined labially. The distance between U6j- horizontal plane and U6j- the coronal plane increased significantly (P<0.05), suggesting that maxillary molar elongated and moved mesially. Frontomaxillary suture changed on the three-dimensional direction, but without significant difference (P<0.05).
Three-dimensional measurements confirm that growth and remodeling of bone suture (such as pterygopalatine suture) play an important role in maxilla development. The maxilla and maxillary teeth move forward and downward, while the mandibular growth is inhibited after maxillary protraction.
采用锥形束CT（CBCT）研究骨性Ⅲ类错牙合畸形上颌前牵引的三维机制。
对14例早期恒牙列骨性Ⅲ类错牙合畸形患者（男6例，女8例，平均年龄10.9岁）进行上颌前牵引治疗。治疗前后均采用CBCT获取Dicom数据，然后用Dolphin 11.0软件进行数字化处理，重建并建立三维坐标系。选取23个标志点进行测量分析。采用SPSS 17.0软件包对数据进行分析。
上颌前牵引后，A点至冠状面距离、SNA及ANB均显著增加（P<0.01）；A点至水平面距离、ANS-PNS显著增加（P<0.05），提示上颌向前下生长。Po-S-N显著增加（P<0.01），而SNB显著减小（P<0.05），提示下颌向下向后旋转，下颌生长受到抑制。U1j至冠状面距离显著增加（P<0.01），提示上前牙向前移动；U1-SN角显著增加（P<0.05），提示前牙唇倾。U6j至水平面和U6j至冠状面的距离显著增加（P<0.05），提示上颌磨牙伸长并近中移动。额颌缝在三维方向上发生改变，但差异无统计学意义（P>0.05）。
三维测量证实骨缝（如翼腭缝）的生长和改建在上颌骨发育中起重要作用。上颌前牵引后，上颌骨及上颌牙齿向前下移动，而下颌生长受到抑制。
