上颌前牵引治疗恒牙早期骨性Ⅲ类畸形前后的三维测量对比

Three-Dimensional Measurement of Skeletal Class Ⅲ Malocclusion in Permanent Dentition before and after Maxillary Protraction

目的通过锥形束CT(cone-beam computed tomography,CBCT)研究骨性Ⅲ类错畸形患者上颌前方牵引治疗前后的变化,从三维方向上探讨上颌前方牵引治疗的机制。方法选取20例恒牙列早期骨性Ⅲ类错畸形患者,采用上颌前方牵引治疗。牵引治疗前后,进行CBCT三维扫描,采用Dolphin11.0对骨组织及牙进行三维重建、建立三维坐标体系,选择相关标志点进行测量并分析。结果上颌前方牵引后,SNA、ANB角显著增大(均P<0.01),AWS-ANS、r/lCo-A和ANS-PNS增加(均P<0.01),上颌骨向前、向下生长;下颌rGo-Me、lGo-Me和ANSMe/N-Me比例未见明显改变(均P>0.05),ANS-Me显著增加(P<0.01);Wits值明显增加(P<0.01)。CBCT示额颌缝等4条骨缝三维方向上均有变化。结论上颌前方牵引后,经CBCT三维测量,证实上颌骨缝的生长改建在上颌骨生长过程中发挥了重要作用,上颌骨明显向前、向下生长;下颌骨生长得到抑制。

Objective To study the changes in skeletal ClassⅢ malocclusion before and after treatment with maxillary protraction by cone-beam CT（CBCT）,and to explore the mechanism of maxillary protraction treatment in three dimensions.Methods Twenty patients with early skeletal ClassⅢ malocclusion in the permanent dentition were treated with maxillary protraction.The CBCT was performed before and after treatment,and the software Dolphin 11.0 was used for three-dimensional reconstruction and coordinate system establishment of bone tissue and tooth.The associated landmarks were chosen for measurement and analysis.Results The SNA angle,ANB angle,AWS-ANS,r/lCo-A,ANS-PNS,ANS-Me and Wits value significantly increased after maxillary protraction（P〈0.01）.The maxilla moved forward and downward.No obvious changes in rGo-Me,lGo-Me and ANS-Me/N-Me ratio were found after treatment（P〈0.05）.CBCT showed that frontomaxillary suture and other three bone sutures changed in three-dimensional direction.Conclusion Three-dimensional CBCT confirmed that the growth and remodeling of bone suture played an important role in maxillary development.The maxilla grew forward and downward,while the mandibular growth was inhibited after maxillary protraction.