Lath D L, Johnson C, Smith R N, Brook A H
Department of Oral Health and Development, School of Clinical Dentistry, University of Sheffield, Sheffield, UK.
Int J Dent Hyg. 2006 Aug;4(3):129-32. doi: 10.1111/j.1601-5037.2006.00191.x.
The aim of this study was to compare an established spectrophotometrical approach for the measurement of stain removal in vitro with a new digital image analysis system.
Eighteen acrylic blocks were stained by cycling them through human saliva (2 min), chlorhexidine (2 min) and tea (1 h), rinsed with deionized water and left to air dry. The absorbance of each block was then measured at 395 nm using a single-beam spectrophotometer. The lightness (L-value) of the stained blocks (after a baseline correction) was measured using digital image analysis. Image acquisition and L-values were obtained using Adobe Photoshop software. The stain removal ability of two whitening toothpastes and deionized water was tested by immersing each stained block in a test slurry (15 g paste/60 ml deionized water) for 1 min, rinsing and finally left to air dry. This cycle was repeated until the blocks had 5 min exposure to the slurry. Absorbance values from spectrophotometry and L-values by image analysis were obtained after each cycle.
Fleiss' coefficient of reliability for intra-operator repeatability of the image analysis system and spectrophotometry was 0.999 for both methods which shows excellent reliability. Pearson's correlation coefficients for the two methods (stain build-up) were 0.976. Test products A, B and C gave correlations of 0.962, 0.998 and 0.817 respectively (stain removal), significant at the 0.01 level.
The image system is a reliable alternative measurement method validated here against spectrophotometry for stain removal in vitro, and can provide full colour measurement.
本研究旨在将一种既定的体外测量污渍清除率的分光光度法与一种新的数字图像分析系统进行比较。
将18个丙烯酸树脂块依次置于人唾液（2分钟）、氯己定（2分钟）和茶（1小时）中进行染色，用去离子水冲洗后自然风干。然后使用单光束分光光度计在395nm波长下测量每个树脂块的吸光度。使用数字图像分析测量染色树脂块（经过基线校正后）的亮度（L值）。使用Adobe Photoshop软件获取图像并得到L值。将每个染色树脂块浸入测试浆料（15克牙膏/60毫升去离子水）中1分钟，冲洗后自然风干，以此测试两种美白牙膏和去离子水的去污能力。重复此循环，直到树脂块在浆料中浸泡5分钟。每个循环后分别通过分光光度法获得吸光度值，并通过图像分析获得L值。
图像分析系统和分光光度法的操作者内重复性的Fleiss可靠性系数在两种方法中均为0.999，显示出极高的可靠性。两种方法（污渍形成）的Pearson相关系数为0.976。测试产品A、B和C的相关系数分别为0.962、0.998和0.817（污渍清除），在0.01水平上具有显著性。
图像系统是一种可靠的替代测量方法，在此针对体外污渍清除率与分光光度法进行了验证，并且能够提供全彩色测量。
