中文摘要：

目的评价显微CT测定V类洞复合树脂充填修复体边缘渗漏的可靠性和优势。方法离体人磨牙制备V类洞，用粘接剂及复合树脂充填修复。将样本牙浸入氨化硝酸银溶液12h及显影液8h。显微CT扫描后测定充填物拾壁及龈壁的银渗漏深度，重建洞壁银渗漏三维图像。正中纵向切开充填物及样本牙，光学显微镜下测量剖面窝洞拾壁及龈壁的银渗漏深度，采用配对秩和检验比较显微CT与光学显微镜测定的渗漏深度差异。结果显微CT和光学显微镜测量的龈壁渗漏深度（中位数分别为0．78和0．74mm）差异无统计学意义（P〉0．05），显微CT测量的猞壁渗漏深度（中位数0．40mm）显著小于光学显微镜（0．72mm）（P〈0．01）；洞壁渗漏的形态呈多样性，部分渗漏存在明显的渗漏通道。结论显微CT能精确测定窝洞龈壁部位的银渗漏程度，并能建立银渗漏三维形态，猞壁部位显微CT测定的渗漏深度不能反映实际渗漏深度。

英文摘要：

Objective To evaluate the reliability and superiority of micro-CT in marginal leakage assessment of Class V restorations. Methods Class V preparations with gingival margins in dentin and occlusal in enamel were made in sixteen extracted non-carious human molars and restored with dental bonding agents and composite resin. All teeth were then immersed in 50% ammonia-silver nitrate solution for 12 hours, followed by developing solution for 8 hours. Each restoration was scanned by a micro-CT and silver leakage was measured and three-dimensional image of the silver leakage alone cavity wall were reconstructed. Afterward, all restorations were sectioned and examined for leakage depth using a microscope. The silver leakage depth of each restoration obtained by micro-CT and microscope were compared for equivalency. Results The silver leakage depths in gingival wall obtained with micro-CT （0. 78 mm） and microscope （0. 74 ram） showed no significant difference （P 〉0. 05）, while the judgment of leakage depths in occlusal wall in＇ micro-CT image （0.40 ram） was affected by adjacent enamel structure, giving less leakage depths compared to microscope （0. 72 mm） （P 〈 0.01 ）. The three-dimensional shapes of the microleakages displayed clearly by micro-CT alone wall of Class V restorations were multiform and some leakages showed channels on their way to spreading. Conclusions Micro-CT can detect precisely the silver leakage in the dentin wall of a restoration and display its three-dimensional shape fully. Enamel structure affects the detection of the silver leakage next to it.