Lee Chulsung, Darling Cynthia L, Fried Daniel
Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, CA 94143-0758, USA.
Dent Mater. 2009 Jun;25(6):721-8. doi: 10.1016/j.dental.2008.11.014. Epub 2009 Jan 23.
The purpose of this study was to assess the potential of polarization-sensitive optical coherence tomography (PS-OCT) to non-destructively measure the depth and severity of artificial demineralization on exposed root surfaces and measure the degree of inhibition by topical fluoride. Although PS-OCT imaging studies have demonstrated the utility of PS-OCT for imaging carious lesions on enamel and dentin surfaces the influence of the cementum layer that is present on intact root surfaces has not been investigated.
In this study, extracted human tooth roots were partitioned into three sections with one partition treated with topical fluoride, one partition protected from demineralization with acid resistant varnish, and one partition exposed to a demineralization solution, producing artificial lesions approximately 200-mum deep in root dentin. The lesion depth, remaining cementum thickness and the integrated reflectivity for lesion areas were measured with PS-OCT. These measurements were also compared with more established methods of measuring demineralization, namely transverse microradiography (TMR) and polarized light microscopy (PLM).
PS-OCT was able to measure a significant increase in the reflectivity between lesion areas and sound root surfaces. In contrast to dentin, the cementum layer manifests minimal reflectivity in the PS-OCT images allowing non-destructive measurement of the remaining cementum thickness. The reflectivity of the cementum layer did not increase significantly after substantial demineralization, however it did manifest considerable shrinkage in a fashion similar to dentin and that shrinkage could be measured with OCT.
This study demonstrates that PS-OCT can be used to measure demineralization non-destructively on root surfaces and assess inhibition of demineralization by anti-caries agents.
本研究旨在评估偏振敏感光学相干断层扫描（PS-OCT）在无损测量暴露牙根表面人工脱矿深度和严重程度以及测量局部用氟化物抑制程度方面的潜力。尽管PS-OCT成像研究已证明PS-OCT在釉质和牙本质表面龋损成像中的应用，但完整牙根表面存在的牙骨质层的影响尚未得到研究。
在本研究中，将拔除的人牙根分成三个部分，一个部分用局部氟化物处理，一个部分用抗酸漆保护以防脱矿，一个部分暴露于脱矿溶液中，在牙根牙本质中产生约200微米深的人工龋损。用PS-OCT测量龋损深度、剩余牙骨质厚度和龋损区域的积分反射率。这些测量结果还与更成熟的脱矿测量方法，即横向显微放射照相术（TMR）和偏振光显微镜（PLM）进行了比较。
PS-OCT能够测量龋损区域与健康牙根表面之间反射率的显著增加。与牙本质不同，牙骨质层在PS-OCT图像中表现出最小的反射率，从而能够无损测量剩余牙骨质厚度。大量脱矿后，牙骨质层的反射率没有显著增加，但其确实表现出与牙本质类似的相当程度的收缩，并且这种收缩可以用OCT测量。
本研究表明，PS-OCT可用于在牙根表面无损测量脱矿情况，并评估防龋剂对脱矿的抑制作用。
