Darling Cynthia L, Huynh Gigi D, Fried Daniel
University of California, San Francisco, 94143-0758, USA.
J Biomed Opt. 2006 May-Jun;11(3):34023. doi: 10.1117/1.2204603.
A fundamental understanding of how near-IR light propagates through sound and carious dental hard tissues is essential for the development of clinically useful optical diagnostic systems, since image contrast is based on changes in the optical properties of these tissues on demineralization. During the caries (decay) process, micropores are formed in the lesion due to partial dissolution of the individual mineral crystals. Such small pores behave as scattering centers, strongly scattering visible and near-IR light. The optical properties of enamel can be quantitatively described by the absorption and scattering coefficients, and the scattering phase function. Our aim is to measure the optical scattering behavior of natural and artificial enamel caries. Near-IR attenuation measurements and angular-resolved goniometer measurements coupled with Monte Carlo simulations are used to determine changes in the scattering coefficient and the scattering anisotropy on demineralization at 1310 nm. An ultra-high resolution digital microradiography system is used to quantify the lesion severity by measurement of the relative mineral loss for comparison with optical scattering measurements. The scattering coefficient increases exponentially with increasing mineral loss. Natural and artificial demineralization increases the scattering coefficient more than two orders of magnitude at 1310 nm, and the scattering is highly forward directed.
对于开发临床实用的光学诊断系统而言，深入理解近红外光如何在健康和龋坏的牙齿硬组织中传播至关重要，因为图像对比度基于这些组织在脱矿过程中光学特性的变化。在龋齿（蛀牙）形成过程中，由于单个矿物晶体的部分溶解，病变部位会形成微孔。这些微小的孔隙充当散射中心，对可见光和近红外光产生强烈散射。牙釉质的光学特性可以通过吸收系数、散射系数以及散射相函数进行定量描述。我们的目标是测量天然和人工龋坏牙釉质的光学散射行为。利用近红外衰减测量、角分辨测角仪测量并结合蒙特卡罗模拟，来确定在1310nm波长下脱矿过程中散射系数和散射各向异性的变化。使用超高分辨率数字显微放射成像系统，通过测量相对矿物质流失来量化病变严重程度，以便与光学散射测量结果进行比较。散射系数随矿物质流失呈指数增加。在1310nm波长下，天然和人工脱矿使散射系数增加了两个多数量级，并且散射具有很强的前向性。
