不同分辨率锥形束CT和全景片在根尖吸收诊断中的对比研究

目的 比较不同分辨率锥形束CT（CBCT）和全景片在根尖吸收诊断中的差异。方法 选取160颗单根前磨牙,用以模拟4种不同程度的根尖吸收：无（完整的牙根）、轻度（根尖区近中、远中、颊面、舌面1.0 mm直径和深度的洞形）、中度（0.4、0.8、1.2、1.6 mm根尖缩短）、重度（2.4、2.8、3.2、3.6 mm根尖缩短）。模拟完成后,对所有牙齿拍摄CBCT（0.2和0.3 mm分辨率）和全景片获取3组X线图像。经校正后,3名正畸临床医师通过对图像资料的分析对所有样本的根尖吸收程度进行诊断。采用McNemar检验对比分析采用不同成像技术诊断不同程度根尖吸收的正确率。结果 采用全景片诊断全部根尖吸收样本的正确率为57.5%,而采用0.2和0.3 mm分辨率CBCT的正确率分别为85%和81.3%。对全部样本的诊断,0.2 mm分辨率CBCT和全景片以及0.3 mm分辨率CBCT和全景片的差异均有统计学意义（P〈0.01）。然而,对无、轻度、重度和全部根尖吸收样本的诊断,0.2和0.3 mm分辨率CBCT间差异无统计学意义（P〉0.05）。结论 相比于全景片,CBCT对根尖吸收具有更高的检出率。在根尖吸收的诊断中,0.2和0.3 mm分辨率CBCT诊断效能无明显差异,但0.3 mm分辨率CBCT对患者的辐射水平更低。

Comparison of cone-beam computed tomography with different voxel resolutions and panoramic imaging for detecting simulated apical root resorption

Objective This study aimed to compare the efficacy of cone-beam computed tomography（CBCT） with different voxel resolutions and panoramic radiography for the detection of simulated extemal apical root resorption（EARR） in vitro. Methods The study sample consisted of 160 single-rooted premolars for simulating EARR of varying degrees according to four setups： no（intact teeth）, mild（cavity of 1.0 mm in diameter and depth on mesial, distal, buccal, and lingual root surface）, moderate（0.4, 0.8, 1.2, and 1.6 mm root shortening）, and severe （2.4, 2.8, 3.2, and 3.6 mm root shortening）. These teeth were imaged by CBCT with two different voxel sizes（0.2 and 0.3 mm） and panoramic radiography. Each root was classified according to defect size（no, mild, moderate, and severe） by three calibrated observers using CBCT and panoramic images. McNemar tests were performed to compare the proportions of correct classification between the methods（0.2 mm voxel vs. 0.3 mm voxel, 0.2 mm voxel vs. panoramic, and 0.3 mm voxel vs. panoramic） for each degree of EARR. Results For panoramic radiography, 57.5% of all samples were correctly classified compared with 85% for 0.2 mm voxel and 81.3% for 0.3 mm voxel, and the differences were significant（P〈0.01） between both 0.2 mm voxel and 0.3 mm voxel and panoramic radiography. However, no significant difference was observed between 0.2 mm voxel and 0.3 mm voxel in correct classification for no, mild, severe, and all samples（P〉0.05）. Conclusion CBCT imaging was more reliable than panoramic radiography for detecting simulated EARR. The 0.3 mm voxel resolution was the better configuration because performed the same as the 0.2 mm voxel resolution in diagnosing simulated EARR but with lower exposure to X-rays .