利用光学相干断层图像平均灰度值定量研究牛恒牙早期人工脱矿

Research on early quantitating artificial demineralization of bovine permanent teeth using the average gray value of optical coherence tomography images

目的 研究经酸蚀脱矿后牛恒牙光学相干断层图像平均灰度值的变化,探讨平均灰度值作为一个参数指标定量检测牛恒牙早期脱矿的可行性.方法 以正常离体牛恒牙为样本,采用凝胶酸蚀法制备人工脱矿模型;用光学相干断层摄影术对人工脱矿模型扫描成像,利用Matlab软件计算不同酸蚀时间脱矿区牙体层110 μm范围内的平均灰度值.将测得图像灰度和归一化后图像灰度,分别进行单因素方差分析.结果 牙体表层110 μm范围内不同时间酸蚀脱矿区的平均灰度值从大到小依次为30 min酸蚀脱矿区、1O min酸蚀脱矿区、0 min酸蚀脱矿区,图像灰度归一化后做单因素方差分析,P＜0.05.结论 牙体表层110 μm范围内不同酸蚀时间脱矿区平均灰度值差异有统计学意义,并随脱矿时间增加而增大,即平均灰度值可以用于光学相干断层摄影术定量检测牙齿的早期脱矿.光学相干断层图像灰度归一化使得不同酸蚀脱矿区的平均灰度值更有可比性,减小了由于样本之间差异引起的误差,提高了平均灰度值作为参数指标定量检测牙齿早期脱矿的可靠性.

Objective To investigate the feasibility of the average gray value as a parameter index for early quantification detection of artificial demineralization by studying the changes of average gray value on optical coherence tomography （OCT） images of bovine permanent teeth etched.Methods Early stage of artificial demineralization mould was created by etching the experimental normal isolated bovine permanent teeth surface.Images of the artificial demineralization mould were obtained by OCT,and then the average gray value within the 110 μm under the teeth surface was calculated by Matlab software.The gray value and the normalized gray value were analyzed by ANOVA,respectively.Results On the OCT images,the average gray value within the 110 μm under the teeth surface form high to low were the areas etched for 30 min、10 min、0 min.After the gray level normalization,the ANOVA analysis obtained P〈0.05.Conclusion There are significant differences among the average gray value obtained from the areas etched for different time length.The average gray values increase progressively with the increasing of etching time,which can be taken as a parameter index of OCT system for early quantification detecting of artificial demineralization.The grey level normalization of OCT images makes the average gray value obtained from different demineralization areas more comparable and it can also reduce the error caused by the individual differences and improve the diagnosis reliability of average gray value as a parameter index of OCT system for early quantification detecting of artificial demineralization.