上颌后牙颊侧种植体支抗植入区CBCT的综合评价

Determining the anatomical characteristics of maxillary buccal area for mini-implants insertion by means of conebeam computed tomographic image

目的以锥束计算机体层摄影术（cone—beamcomputedtomography，CBCT）评估上颌后牙颊侧种植体支抗植入区的解剖特点，为临床种植钉的成功植入提供参考。方法成人和儿童各21名进行CBCT扫描，选取距上颌第一磨牙远中颊侧釉牙骨质界（CementoEnamelJunction，CEJ）4mm和7mm两个截面作为参考平面，对上颌左右侧5～6根间和6～7根间的皮质骨厚度和密度、松质骨密度、根间最短距离和皮质骨距根间最窄处距离进行测定并进行配对t检验。结果随着年龄增长，上颌第一磨牙颊侧从近中向远中皮质骨厚度和骨密度均增大（P〈0．05）；皮质骨距根问最窄处距离平均值大于5mm。结论选择上颌第一磨牙远中为植入点，采用直径1．3～2．0mm，螺纹长度6mm的种植钉，以与骨面成30°的小角度植入，可使种植钉植入更为安全稳定，但儿童谨慎使用种植钉。

ObjectiveTo evaluate the application of eonebeam computed tomography in determining the anatomical characteristics of the maxillary posterior region so as to obtain scientific knowledge for conducting mini-implants. Methods 21 juvenile and 21 adult patients were divided into two groups. A CBCT examination was applied to each sample. Two horizontal planes, which were 4 mm and 7mm respectively from the CEJ at the distal：buccal of the maxillary first molar, were selected as the subjects for study. Cortical bone thickness, bone density, narrowest interradicnlar distances and shortest distance from cortical bone surface to the narrowest interradicular space were measured and analyzed by Paired t test. Result There were significant differences between adolescents and adults, with adults cortices significantly thicker and cortical bone density significantly higher from mesial to distal（P 〈0.05）. The average distance from the surface of the cortical bone to the area of the closest interradicular space was over 5 mm in the most region. Conclusion Safe and stable placement of a mini-implant can be conducted as follows： distal to the first molar, the safest length is 6 mm of thread with a diameter of 1.3 mm-2mm; the best angulation is 30° to the surface of bone. This study suggests that implanting for adolescent patients must be conducted prudently.