Heterogeneity of auto-fluorescence of human tooth tissue progressed by aging

用时间分辨荧光显微光度计研究了人牙本质颊舌六个区域和纵向自荧光强度的年龄变化。静态测量模式显示，各区域荧光强度随年龄增长而增加。最大荧光波长和半最大荧光光谱全宽度没有变化；在所有研究的牙齿的所有区域，前者和后者的值分别在440nm和100nm左右。动态模式表明，440nm波长的自荧光至少有三种荧光成分，荧光衰减时间不同，分别为快、中、慢。在6个区域，这些成分的荧光强度随着年龄的增长而增加；在18岁以后，快速成分的荧光强度随衰老的比例增加，而其他两种成分的荧光强度在老年牙齿的增加速率下降。三种成分强度与静态荧光强度之比的年龄变化在纵向区域有明显的差异；冠状牙本质中快成分的比例随年龄增长而增加，而根尖牙本质中慢成分的比例随年龄增长而减少。在前两个区域之间的趋势在颈牙本质可见。以上结果表明，年龄的变化规律在纵向上存在差异，由此推断冠状牙本质与根尖牙本质之间影响年龄变化的因素存在差异。

Age changes of auto-fluorescence intensities of six regions of buccolingual and longitudinal directions in human dentin were studied using a time-resolved fluorescence microphotometer. Static measurement mode showed that fluorescence intensity increased with aging in the all regions. Wavelength of the maximum fluorescence and full width of half maximum of fluorescence spectrum, however, did not change ; the values of the former and the latter were around 440nm and about 100nm, respectively, in the all regions of all teeth studied. The dynamic mode suggested that the auto-fluorescence of 440nm wavelength had at least three fluorescent components with different fluorescence decay times, fast, intermediate and slow. Fluorescence intensities of these components increased with aging in the six regions ; the intensity of the fast component showed an increase in proportion to aging after 18 years old, while in the other two components, the increasing rate of fluorescence intensities decreased at old aged teeth. Age changes of ratios of intensities of the three components to the static fluorescent intensities were distinguishable among the regions of longitudinal direction ; the ratio of the fast component increased with aging in the coronal dentin, while in the root apex dentin, the ratio of the slow one decreased. A tendency intermediate between the former two regions was seen in the cervical dentin. The above results showed that patterns of age changes were different in the longitudinal direction, from which it was inferred that factors affecting age changes were different between the coronal and root apex dentins.