人天然牙的高分辨X线微区衍射分析

Microdiffraction Measurements of Natural Tooth by High Resolution X-ray Diffraction Equipment

通过使用X线微区衍射法直接对人天然牙表面正常牙釉质、牙本质及龋坏组织三个测量点进行检测,以测试X’pert Pro型衍射仪对人天然牙正常和早期龋损组织晶体结构改变的检测能力。结果显示,牙磷灰石由多种物相构成,是一种生物混晶,主要物相为羟基磷灰石,龋坏组织中可能有新物相的形成。从正常牙釉质到牙本质再到龋坏组织,晶体a轴逐渐增大,c轴基本不变。晶体晶胞参数计算结果:正常牙釉a=9.550,c=6.883;正常牙本质a=9.554,c=6.883;龋坏组织a=9.558,c=6.884。晶粒尺寸计算结果:正常牙釉质D002=27.600nm;正常牙本质D002=16.561 nm;龋坏组织D002=13.163 nm。结晶性:正常牙釉质>正常牙本质>龋坏组织。结果表明采用新型高分辨X线衍射仪可以非常方便地对牙齿进行X线衍射微区分析。

The main mineral component of natural tooth was determined as calcium apatite many years ago; most of them exist in the form of hydroxyapatite with different crystallites. If a tooth decayed, the crystalline of hydroxyapatite would be changed and decomposed. In our experiment, a natural tooth with caries was measured by high resolution XRD equipment： X＇pert Pro. Three spots which included normal enamel, normal dentin and caries tissue were analyzed. The results showed that tooth was a kind of biological mixed crystal composed of many crystal phases, the main crystal phase was hydroxyapatite. From normal enamel to normal dentin and to caries tissue, the length of the a-axis of hydroxyapatite crystaUite increased, the length of the c-axis of hydroxyapatite crystallite remained unchanged. The crystal sizes were： normal enamel D002 = 27. 600nm; normal dentin D002 = 16. 561nm; caries tissue D002 = 13. 163nm. Crystallinity： normal enamd〉normal dentin〉caries tissue. According to our experiment, tooth could be conveniently studied by high resolution microdiffmcion XRD equipment.