临界病例拔牙与不拔牙矫治对牙颌面硬组织结构的影响

目的:比较拔牙或不拔牙矫治对临界病例牙颌面硬组织结构变化的影响.方法:以5位正畸专家临床判断出的33个临界病例为样本,在头颅定位侧位片上测量上述病例治疗前后牙颌面硬组织的变化,再根据这33名患者实际接受的拔牙还是不拔牙、以及拔第一双尖牙还是拔第二双尖牙治疗进行分组.33例中有12例采用了不拔牙治疗,13例采用了拔4个第一双尖牙治疗,8例采用了拔4个第二双尖牙治疗.用头影测量学上常用的20项硬组织测量项目进行分析比较.结果:临界病例拔牙组与临界病例不拔牙组在治疗前的牙颌面硬组织结构没有统计学意义的差别;拔第一双尖牙组的前颅底平面-下牙槽座点角(SNB角)比拔第二双尖牙组的SNB角小(4.0±1.3)°(P<0.01);治疗后拔牙组与不拔牙组以及拔第一双尖牙组与拔第二双尖牙组之间的差别主要为牙位改变.结论:临界病例很难通过常规头影测量来区分是否需要拔牙治疗;这两种治疗方案的差别主要表现为前牙矢状方向突度及倾斜度的变化,而颌骨位置关系及垂直方向上下颌、牙合、颅底平面角没有显著性差别;与拔第一双尖牙相比,拔第二双尖牙可以较好的保持上切牙的唇倾度不减小,且拔第二双尖牙对牙颌面结构的影响效果与不拔牙治疗相近,但拔第一双尖牙可以明显减小上下前牙的突度和倾斜度.

Cephalometric comparison of hard-tissue morphology between extraction and non-extraction orthodontic treatment in borderline cases

OBJECTIVE:To compare hard-tissue morphology by cephalometric measurements between extraction and non-extraction orthodontic treatment in borderline cases. METHODS: The samples consisted of 33 cases selected as borderline cases by 5 orthodontic specialists. They were divided into 21 extraction cases (including 13 four first premolar extraction cases and 8 second premolar extraction cases) and 12 nonextraction cases by checking patients' treatment records. Conventional cephalometric analysis was made to compare hard tissue structures before and after orthodontic treatment and the same comparison was made between two different extraction patterns. RESULTS: No statistical difference was found on pretreatment hard-tissue morphology between extraction and non-extraction groups divided from borderline cases. The SNB angle of the four first premolars extraction group was smaller than that of the four second premolars extraction group by (4.0+/-1.3) degrees P<0.01 . The statistical significant differences of the post-treatment hard-tissue cephalometry between extraction and nonextraction and between two different extraction patterns were found to be limited to the items related to the tooth position. CONCLUSION: Conventional cephalometric analysis cannot differentiate extraction or non-extraction treatment selection from borderline cases. The differences between extraction and non-extraction orthodontic treatments were limited to tooth positions but had no skeletal relation. Extraction of the four second premolars could prevent upper incisors from uprighting as it often follows the four first premolar extraction treatment. Extraction of the four first premolars could change the incisor position much more than extraction of the four second premolars. The changes of four second premolar extraction treatment were much similar to non-extraction treatment.