不同牙硬组织成分的太赫兹时域光谱特征研究

Properties of human dental hard tissues by THz-SDs transmission system

目的应用太赫兹时域光谱技术探索透射模式下不同牙体硬组织成分的太赫兹物理特性,寻找最佳成像参数和成像频段。方法收集陆军军医大学第一附属医院口腔科因阻生需拔除的完整无龋人第三磨牙,制备带有正常牙釉质和牙本质结构的近远中向牙磨片共15枚,序列水砂纸打磨并抛光至相同厚度。在透射模式下,利用太赫兹时域光谱技术分析计算0.2~1.3 THz频段内的吸收系数、折射率和其比值,并获取相应的曲线。结果 (1)牙釉质和牙本质吸收系数在0.3、0.5和0.6 THz频率上差异有统计学意义(P<0.05);(2)牙釉质和牙本质的折射率在0.2~1.3频段内差异有统计学意义(P<0.05);(3)利用折射率更加适合于牙硬组织的成像,并在0.3 THz处具有最佳对比能力。结论太赫兹技术可用于辨识牙釉质和牙本质,且折射率更加适合于牙体硬组织成像,在0.3 THz处牙釉质和牙本质的折射率对比度最大。

Objective To explore the spectroscopical properties of human normal enamel and dentine by Terahertz time-domain spectroscopy （THz-SDs） transmission system, and to investigate the best parameter and frequency for imaging. Methods Fifteen intact third molars were freshly extracted and sliced mesiodistally to 0.7 mm in thickness, and ground serially with sand-papers under running tap water. Terahertz spectrum of enamel and dentin were obtained with the THz-SDs, and then the absorption coefficient, refractive index and refractive index ratio of the dental hard tissues were calculated in the frequency of 0.2 to 1.3 THz. Results ①The absorption coefficient of enamel was statistically significantly different with that of dentin at 0.3, 0.5 and 0.6 THz （P〈0.05）; ② Obvious differences were also observed in the refractive index between enamel and dentin at the range of 0.2-1.3 THz （P〈0.05）; ③ Since the refractive index may be more suitable to image the human dental hard tissue, and 0.3 THz was chosen to get the best contrast. Conclusion Terahertz can be used to identify enamel and dentin, and refractive index is more suitable to image dental hard tissue. At 0.3 THz, the refractive index contrast of enamel and dentin is the largest.