Objective

This study evaluated the capability of profilometry, microhardness, Optical Coherence Tomography (OCT) and Tandem Scanning Confocal Microscopy (TSM) in characterising the early erosive lesion in polished and natural human enamel in vitro.

Methods

Polished (n = 60) and natural (n = 60) human enamel surfaces, were immersed and agitated in 0.3% citric acid erosion at 0 s, 10 s, 30 s, 60 s, 120 s, and 300 s (n = 10). Changes in the surface were measured with 3D-step height change (μm), surface roughness (μm), surface microhardness (KHN), and images were assessed qualitatively with OCT and TSM.

Results

Mean (SD) 3D-step height change (μm) was measurable for polished enamel at: 60 s (0.24 ± 0.1), 120 s (1.16 ± 0.71), 300 s (2.01 ± 0.47; p < 0.05); a step height change was not detectable on acid challenged natural enamel surfaces. Mean (SD) surface roughness (μm) of polished enamel was detected at 10 s (0.270 ± 0.013; p < 0.05) and all erosion periods; and in natural enamel detected after 120 s (0.830 ± 0.125) and 300 s (0.800 ± 0.140; p < 0.005). Polished enamel Mean (SD) microhardness (KHN) statistically significantly decreased at all time points (p < 0.001); this was unmeasurable for natural enamel. Qualitative image analysis of both surface types indicated erosive change at the surface level, with progression after increasing erosion time.

Significance

The early erosive lesion in polished enamel could be characterised quantitatively surface roughness and microhardness and qualitatively using OCT and TSM; whilst in natural enamel only surface roughness could be utilised. Further investigation of early erosion in natural enamel is required to develop new more clinically relevant models.

中文翻译：

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抛光和天然人类瓷釉中早期糜烂性病变的体外评估

客观的

这项研究评估了轮廓测定法，显微硬度，光学相干断层扫描（OCT）和串联扫描共聚焦显微镜（TSM）表征体外抛光和天然人牙釉质早期侵蚀性病变的能力。

方法

在0秒，10秒，30秒，60秒，120秒和300秒（n = 10）下，将抛光的（n = 60）和天然的（n = 60）人类搪瓷表面浸入并搅动在0.3％的柠檬酸侵蚀中）。用3D步高变化（μm），表面粗糙度（μm），表面显微硬度（KHN）测量表面变化，并使用OCT和TSM定性评估图像。

结果

抛光搪瓷的3D步长平均变化（μm）可在以下时间测量：60 s（0.24±0.1），120 s（1.16±0.71），300 s（2.01±0.47; p  <0.05）; 在受酸侵蚀的天然瓷漆表面上无法检测到台阶高度变化。在10 s（0.270±0.013; p  <0.05）和所有腐蚀时间下，检测到抛光瓷釉的平均（SD）表面粗糙度（μm）。并且在120 s（0.830±0.125）和300 s（0.800±0.140; p  <0.005）之后的天然搪瓷中检测到。在所有时间点，抛光瓷釉的平均（SD）显微硬度（KHN）均在统计学上显着降低（p <0.001）; 这对于天然搪瓷来说是无法测量的。两种表面类型的定性图像分析表明，在表面水平上发生了侵蚀性变化，随着侵蚀时间的增加，腐蚀程度逐渐增加。

意义

使用OCT和TSM可以定量表征抛光釉质中的早期侵蚀性病变的表面粗糙度和显微硬度，并进行定性分析。而在天然搪瓷中，只能利用表面粗糙度。为了开发新的更临床相关的模型，需要对天然釉质中的早期侵蚀进行进一步的研究。