中文摘要：

目的通过对早期自然龋变光学相干断层成像（OCT）图像进行定量分析，寻找适于光学相干断层成像技术检测早期龋的定量参数指标。方法选取D0期、D1期和D2期自然发生釉质龋双尖牙标本各3颗，利用光学相干断层成像分别对上述不同程度早期釉质龋人离体牙进行扫描，并以龋变区域（Et标区域）平均灰度值与正常区域（背景区域）平均灰度之比值（OBC）为定量参数，分析不同龋变程度离体牙光学相干断层二维图像OBC值的趋势。结果在同样深度范围内，随着龋变程度的增加，OBC值呈先增后减的趋势，即：从正常期到D1期，OBC值随着龋变程度的增加而增加；从D1期到D2期，OBC值随着龋变程度的增加而减小。结论OBC值可反映早期自然釉质龋的龋变程度，适于作为光学相干断层成像早期龋定量分析的参数指标。

英文摘要：

Objective Quantitative analysis of optical coherence tomography （OCT） images of naturally occurred early enamel caries was performed to find quantitative parameter indicator for detecting early caries by OCT. Methods Three human premolars with enamel natural caries in DO, D1, and D2 stages were selected respectively and scanned by OCT. The ratios of the average gray value of the caries region （object region） and sound region （background region）, namely, the object-background contrast （OBC） were calculated in OCT images and selected as the quantitative parameters to analyze the OBC trend of different degree of enamel caries. Results Within the fixed depth, the OBC value showed a trend of first increase and then decrease with the severity of dental caries, indicating that OBC value increased with the severity of dental caries from normal to D1 stage, and then decreased from D1 to D2 stage. Conclusion The OBC value can be used as a new quantitative indicator for OCT to estimate the severity of naturally occurred early caries.