Suckling G W, Nelson D G, Patel M J
Adv Dent Res. 1989 Sep;3(2):219-33. doi: 10.1177/08959374890030022301.
Defects present in 12 human permanent teeth were classified on the basis of their macroscopic appearance as hypoplasia (three teeth), diffuse opacities (three teeth), white demarcated opacities (one tooth but two defects), or yellow demarcated opacities (five teeth but six defects). The hardness values and SEM appearance of the defective enamel were determined after the teeth were sectioned through the lesion(s) and were distinctive for each type of defect. The thin enamel of the hypoplastic lesions was either opaque (with reduced hardness values) or translucent (with near-normal hardness values and sometimes a change in prism orientation external to an incremental line). The enamel of the diffuse and demarcated opacities was of normal thickness. The changes in the macroscopic and SEM appearance, and the reduced hardness values of the diffuse patchy opacities, were restricted to the outer 150 microns of the enamel. The demarcated opacities varied in position and depth, and in places had a clearly marked boundary with the adjacent normal enamel. Hardness values were related to color change, with yellow lesions being softer than white. Although prism direction was normal within demarcated opacities, prism outlines were less distinct. The findings suggest that temporary and permanent dysfunction of ameloblasts can occur in both secretory and maturation phases, influencing the final appearance of the lesion.
根据肉眼外观，将12颗人类恒牙中存在的缺陷分为发育不全（3颗牙）、弥漫性混浊（3颗牙）、白色界限性混浊（1颗牙但有2处缺陷）或黄色界限性混浊（5颗牙但有6处缺陷）。在牙齿通过病变部位切片后，测定了缺陷釉质的硬度值和扫描电镜外观，每种类型的缺陷都有其独特之处。发育不全病变的薄釉质要么不透明（硬度值降低），要么半透明（硬度值接近正常，有时在生长线外的棱柱方向发生变化）。弥漫性和界限性混浊的釉质厚度正常。弥漫性斑片状混浊在肉眼和扫描电镜外观上的变化以及硬度值的降低仅限于釉质的外150微米。界限性混浊在位置和深度上各不相同，在某些地方与相邻的正常釉质有明显的边界。硬度值与颜色变化有关，黄色病变比白色病变软。虽然在界限性混浊内棱柱方向正常，但棱柱轮廓不太清晰。这些发现表明，成釉细胞的暂时和永久性功能障碍可发生在分泌期和成熟期，影响病变的最终外观。
