Wright J T, Robinson C, Shore R
Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill.
Oral Surg Oral Med Oral Pathol. 1991 Nov;72(5):594-601. doi: 10.1016/0030-4220(91)90499-3.
Amelogenesis imperfecta (AI) comprises a diverse group of hereditary enamel disorders that are characterized by hypoplastic and in some cases hypomineralized defects. The specific biochemical abnormalities remain unknown for all AI types, making histologic and chemical analyses of affected dentitions essential for resolving the etiology of AI. The purpose of this investigation was to characterize the ultrastructure and mineral content of smooth hypoplastic AI enamel. The AI enamel showed no evidence of surface pitting and was uniformly reduced in thickness by approximately 60% compared with control enamel. Imbibition studies indicated that the AI enamel was generally porous. The first 30 microns of AI enamel adjacent to the dentinoenamel junction was translucent with poorly formed prisms. Abnormal prism structure was seen throughout the AI enamel. Amorphous, presumably organic material that may have been retained enamel protein was also seen. Although the crystallite widths were similar in both AI and normal enamel, the AI teeth showed areas where the crystallite order and continuity appeared disrupted. The mean mineral content was similar for all variables measured except sodium, which was significantly lower in the AI teeth. The calcium concentration was very low in the AI enamel directly adjacent to the dentinoenamel junction and showed a steeper concentration gradient moving from the dentin to the surface compared with control teeth. It may be concluded that the ameloblasts in smooth hypoplastic AI produce a tissue of reduced thickness, which is excessively porous and displays alterations in its ultrastructural organization.
釉质发育不全（AI）是一组多样的遗传性釉质疾病，其特征为釉质发育不全，在某些情况下还伴有矿化不足的缺陷。所有类型的AI具体生化异常仍不清楚，因此对受影响牙列进行组织学和化学分析对于明确AI的病因至关重要。本研究的目的是对平滑型发育不全AI釉质的超微结构和矿物质含量进行表征。AI釉质未显示表面点蚀迹象，与对照釉质相比，厚度均匀减少约60%。吸液研究表明，AI釉质通常具有多孔性。与牙釉质交界处相邻的AI釉质最初30微米呈半透明状，棱柱体形成不良。在整个AI釉质中均可见到异常的棱柱体结构。还可见到可能保留了釉质蛋白的无定形、推测为有机的物质。尽管AI釉质和正常釉质中的微晶宽度相似，但AI牙齿显示出微晶排列顺序和连续性似乎受到破坏的区域。除钠外，所有测量变量的平均矿物质含量相似，AI牙齿中的钠含量显著较低。与对照牙齿相比，紧邻牙釉质交界处的AI釉质中的钙浓度非常低，并且从牙本质到表面显示出更陡的浓度梯度。可以得出结论，平滑型发育不全AI中的成釉细胞产生的组织厚度减小，孔隙过多，并且其超微结构组织发生改变。
