种植支抗辅助内收前牙后牙槽骨的改建

Dental alveolar effects of maxillary anterior teeth retraction with implant anchorage:A computed tomography evaluation

目的:探讨种植支抗在大幅度内收前牙后牙槽骨的改建状况。方法:12例正畸治疗患者,上牙槽前突,UD-SN、U1-SN大于正常一个标准差,轻度拥挤,正畸需拔除第一前磨牙,以种植支抗辅助内收切牙。其中,男3例,女9例,年龄20～54岁,平均25岁;正畸治疗前、后,分别拍摄头颅CT、三维重建,确定每颗牙的正中矢状面、牙长轴,分别在牙槽嵴、牙根1/2、根尖3个平面,测量每颗前牙的唇、腭侧牙槽骨厚度,分析牙槽骨随牙移动的改建程度。测量数据应用SPSS10.0软件包进行配对t检验。结果:测量数据显示,牙槽嵴区牙槽骨唇侧增厚,舌侧变薄;在根中和根尖处,唇侧变薄,舌侧增厚。牙相对于牙槽骨作倾斜移动,正畸治疗前、后比较,有显著性差异,P<0.05。牙根尖移向唇侧骨皮质,牙根颈部移向牙槽骨舌侧;在个别牙发现牙根的唇侧骨皮质开窗,根尖明显穿破骨皮质,横断面可见根尖处骨皮质断裂、不连续。结论:种植支抗增强了正畸移动牙的能力,但牙移动中仍无法避免倾斜移动,牙槽骨腭侧致密的骨皮质改建缓慢,限制了牙的移动。在种植支抗辅助正畸治疗中,应避免盲目及过度矫正,造成牙周支持组织永久性损伤。

PURPOSE： To evaluate the changes that occur in alveolar bone as a result of maxillary anterior teeth retraction with implant anchorage. METHODS： Twelve patients with maxillary dentoalveolar protrusion and mild crowding, underwent orthodontic treatment by extracting the 4 first premolars.The anterior teeth were retracted with implant anchorage. CT scans were made before and after retraction of the anterior teeth.The bone thickness was measured on three levels,i.e.,the crest （S1）, root midpoint （S2） and apical portion（S3） of the long axis of the tooth. Paired t test was used to evaluate the bony changes with SPSS10.0 software package. RESULTS： The measurements of the CT scans showed that in the maxillary anterior arch, the labial S1, lingual S2, and lingual S3 ,had a significant increase in bone thickness （P〈0.005）. The measurements of lingual S1, labial S2, and labial S3 showed significant decrease in bone thickness （P〈0.005）. The incisors＇s apical portion moved to against the labial alveolar cortical bone, the cervical portion moved to approach the lingual alveolar cortical bone after retraction of the incisors. Bone dehiscence was found in some teeth. CONCLUSIONS： The results suggest that maxillary incisors are retracted primarily by controlled tipping of the teeth. Retraction of tooth movement is limited by palatal cortical bone, forcing the tooth against the cortical bone may cause adverse sequelae. Implant anchorage used to add retraction of anterior teeth must be carefully monitored to avoid negative iatrogenic effects. Supported by Shanghai Leading Academic Discipline Project （Grant No.Y0203）and Research Fund of Science and Technology Committee of Shanghai Municipality（Grant No.05B224）