中文摘要：

背景：光学相干层析成像技术是一种高分辨率、非创伤性成像技术,它能够利用近红外光产生牙体组织的深度解析图像,并通过检测背向散射信号来对龋损进行定量检测。 目的：通过与偏振光显微镜的对比,验证光学相干层析成像技术对光滑面早期釉质龋的成像能力及对龋损深度定量检测的准确性。 方法：以6岁龄牛下切牙为样本,采用pH循环法建立光滑面早期龋人工模型,分别应用全光纤光学相干层析成像技术和偏振光显微镜进行检测,比较两种方法获得龋损图像和深度值,进行方差分析和相关性分析。 结果与结论：光学相干层析成像系统能够清晰成像光滑面早期龋,表层下脱矿区域信号显著增强,并且测得的脱矿深度值与偏振光显微镜结果一致,即该系统对深度的测量具有较高的准确性,可用于对早期龋纵深进展的评估。光学相干层析成像技术测得的人工龋模型开窗区的深度值与脱矿时间无相关性（P〉0.05）。计算开窗区平均深度值与开窗区外平均深度值的差值即深度变化值（△D）,则△D与脱矿时间呈正相关（r=0.954,P〈0.05）。结果提示了这种无创、高分辨率的光学成像技术在早期龋的定量研究和临床诊断方面具有广阔的应用前景。

英文摘要：

BACKGROUND： Optical coherence tomography （OCT） is a noninvasive imaging modality with high resolution. It can produce depth-resolved images of tooth utilizing near-infrared light and quantitatively examine the caries by detecting the backscatter signals. OBJECTIVE： To explore the ability ofimaging the early enamel caries on the smooth surface and the accuracy of quantifying the caries depths with OCT via the comparative study of OCT and polarized light microscope. METHODS： The early enamel caries model on the smooth surface was prepared through a pH cycling model with calf （ 6 years old） lower incisor as sample, and detected by an all fiber-based OCT and polarized light microscope. The images and caries depths from both methods were compared using ANOVA and Pearson correlation. RESULTS AND CONCLUSION： OCT could image the early enamel caries. The reflectivity within the demineralized subsurface enamel was markedly greater than the sound enamel in the OCT images. There were no differences in caries depths between OCT and polarized light microscope. OCT, which could accurately quantify the caries depths, may be used to evaluate the longitudinal progress of the early caries. There was no correlation between the lesion depth and demineralization time （P〈0.05）. The altered depths between interior and exterior of the test region were calculated. The increased depths were correlated with the demineralization time （r = 0.954, P〈0.05）. Results suggested the wide prospect of this nondestructive and high-resolution method on the research and clinical diagnosis of early caries.