牙齿龋损是人类一种广泛存在的口腔疾病, 如何能够尽早的发现早期龋齿, 对患者牙齿龋损的预防与治疗具有重要意义。 介绍了基于光热效应的光热锁相热成像技术, 光热锁相热成像技术具有无损伤、 高效率及探测面积大等优势被广泛应用于各类材料的无损检测。 基于光热锁相热成像技术原理对人为模拟龋损的人类离体牙齿组织进行成像检测试验研究。 首先开展了对不同模拟龋损位置离体牙齿的光热锁相成像试验, 采用防酸指甲油对牙齿组织测试面进行开窗受控龋损（开窗大小为5 mm×5 mm）, 其中模拟龋损部位分别选择在牙齿组织的邻接面及牙颌面。 试验结果显示, 牙齿组织模拟龋损位置热波幅值增大, 相位滞后增大且光热锁相成像的幅值图与相位图与X射线成像相比对模拟龋损部位表现出高敏感及高特异性; 光热锁相成像技术对邻接面龋损比牙颌面龋损具有较高特异性。 其次开展了对平滑面牙齿组织样本的多天(0, 1, 2, 4及6 d)模拟龋损光热锁相成像跟踪试验研究, 牙齿组织龋损程度采用X射线方法进行量化。 试验结果表明, 当龋损时间小于6 d时, X射线方法无法对龋损位置进行有效识别, 而采用光热锁相热成像技术检测模拟龋损1 d的牙齿组织时, 幅值差为3.82, 相位差为10.57°, 证明光热锁相热成像方法对牙齿组织龋损具有较高敏感性。 提取的光热锁相成像幅值与相位与龋损时间具有良好的相关性。

According to the World Oral Health Report 2003, dental caries remains a major public health problem in most countries. Early detection is very important to the diagnosis and treatment of caries. The traditional dental caries detection methods, such as visual examination, probes, X-ray and other detection methods with low sensitivity and strong subjectivity, cannot meet the requirements of detecting early caries with high accuracy, reliability and specificity. Therefore, it is of great significance to find a kind of non-destructive, non-contact, high sensitive and high specific method to detect early caries. thermophotonic lock-in imaging (TPLI) detection technology based on photothermal effect is a non-destructive detection technology, and TPLI has the merit of high detection efficiency, large detection area and understandable detection result.Therefore, in this paper, artificially created demineralized on enamel of dental tissue was detected by TPLI, the detection ability of TPLI for caries regions which were selected on smooth surface, adjacent surface and the occlusal surface was investigated. The experimental samples were five molar teeth that had health surfaces and no visible defects, stains, or cracks. Two of them were spliced adjacently by epoxy glue to simulate adjacent surface. All samples were created 5 mm×5 mm rectangular windows on the smooth respectively , adjacent and occlusal surface, other surfaces were coated by acid-proof nail polish. Furthermore, the samples that artificially created demineralized on three different surfaces were imaged by TPLI and X-ray radiography after demineralized two days in the lactic acid gel (pH=4.5). The results showed that the amplitude value of caries area was larger than that of healthy area the phase delay became bigger due to demineralization. The amplitude images and phase images of TPLI were more sensitivity and more specificity to the artificial demineralization than the X-ray radiography. The smooth surface of a sample was selected to demineralize for different days, 1, 2, 4 and 6 d. Then the sample was imaged with TPLI and a X-ray radiography to decide quantitatively the degree of demineralization to prove the detection ability of TPLI. The results showed that the difference value of amplitude (healthy area amplitude and caries area amplitude) was 3.82 and the difference value of phase was 10.57° after 1d demineralization. However, X-ray detection method cannot recognize caries within demineralized 6d. The amplitude images and phase images of TPLI were consistent changes with caries time, and can found the caries very early. This paper proves the significance of TPLI to diagnosis and treatment of teeth.