牙本质龋的太赫兹成像研究

牙本质龋与牙髓感染状态及活力密切相关，龋损深度则决定临床治疗方案，但目前牙本质龋的检测及诊断方法如：视诊、探诊容易受到主观因素影响；X线辅助检查对龋病灵敏度低等，都有一定缺陷，可靠性及有效性仍有待提高。太赫兹时域光谱可以利用不同的物理参数成像，在牙本质龋在体、无损检测方面有较大应用潜力。为探索牙本质龋损的太赫兹光谱图像开展本研究。实验通过搭建透射、反射式扫描太赫兹平台，对15枚含牙本质龋离体牙磨片扫描，通过数据二维重构，获得了不同参数的太赫兹透射和反射图像，再将太赫兹图像与实验室研究龋病的光镜图像与X线图像对比、拟合并进行光镜下、太赫兹图像下龋损面积评价。结果表明：太赫兹图像与光镜图像相符，较X线图像灵敏度更高。反射模式下由于太赫兹反射信号较弱，使得样品厚度，表面粗糙程度以及系统噪声对实验结果影响较大，图像仅能辨识样本轮廓，不能用于区分牙釉质、牙本质及牙本质龋。透射模式下的频域1.4 THz相位差成像、时域信号最小值对应的时间成像都能区分牙釉质，牙本质和牙本质龋，可以用来鉴别三者，其中最小值对应的时间成像效果最佳。对光镜下测得牙本质龋损面积与太赫兹透射模式下的时域信号最小值对应的时间图像测得的牙本质龋损面积进行配对样本Wilcoxon符号秩和检验，结果（p＞0.05）尚不能认为两种方法测得的牙本质龋损面积有差别，两种方法测量的差值源于系统误差。故可以认为通过太赫兹透射模式下的时域信号最小值对应的时间图像获得牙本质龋损范围、大小等诊断信息。研究表明太赫兹成像技术可以为牙本质龋的早期诊断提供更为精确有效且无电离辐射的诊断方法，为临床数字化、微创去龋提供一定形态学依据。

Terahertz Imaging Study of Dentin Caries

Dental caries are closely related to pulp infection status and vitality, and the depth of caries determines the clinical treatment. However, the detection and diagnosis methods of dentin caries, such as visual examination and probe, are easily affected by subjective factors. X-ray assistive examination for caries has low sensitivity and some defects, and its reliability and effectiveness still need to be improved. Terahertz time-domain spectroscopy can image different physical parameters, which has great potential in the physical and nondestructive detection of dentin caries. This study aimed to explore terahertz spectral images of dentin caries. Experiment by transmission and reflection type scanning terahertz platform, to 15 containing dentine caries in vitro teeth grinding slice scanning, through the data of two-dimensional reconstruction, won the terahertz transmission and reflection of different parameters in the image. Terahertz images and laboratory studies of dental decay light image and X-ray image contrast, the proposed merger under light microscopy, THz image caries damage area is under evaluation.The results show that the terahertz image is consistent with the light mirror image and has higher sensitivity than the X-ray image.Under the reflection mode, the sample thickness, surface roughness and system noise greatly influence the experimental results due to the weak THz reflection signal. The image can only identify the contour of the sample but cannot be used to distinguish enamel, dentin and dental caries.In the transmission mode, both the frequency domain 1.4 THz phase difference imaging and the time domain imaging corresponding to the minimum signal can be used to distinguish enamel, dentin and dental caries, and the time imaging corresponding to the minimum signal can be used to distinguish the three, among which the time imaging corresponding to the minimum signal has the best effect.Measured under the light dentine caries damage area and terahertz time-domain signal of transmission mode for the minimum time corresponding image of dentine caries damage area matching samples Wilcoxon signed-rank and inspection. The results (p>0.05) still cannot think of two methods in the area of dentine caries loss difference, two methods of measuring the difference due to system error.Therefore, we can think that the diagnostic information such as the range and size of dentin caries can be obtained through the time-image corresponding to the minimum value of time-domain signal in the terahertz transmission mode.This study shows that terahertz imaging technology can provide a more accurate and effective diagnostic method without ionizing radiation for the early diagnosis of dentin caries and provide some morphological basis for clinical digitalization and minimally invasive caries removal.