Introduction

Amelogenin (AMEL) plays critical roles during enamel and dentin matrix deposition and mineralization. Most studies focused on the expression patterns of AMEL through the bud, cap, and bell stages. The spatial-temporal expression of AMEL protein during different mineralization stages, especially from presence of crypts to crown completed stages, remains unknown. Thus, the distribution pattern of AMEL in tooth crown formation from Nolla Stage 1 to 6 was investigated.

Methods

Porcine mandibular molar tooth germs from Nolla Stage 1 to 6 were obtained. The dynamic morphologic changes of tooth germs were examined by X-ray and surgical operating microscope. The AMEL protein expression was evaluated immunohistochemically, then analyzed semi-quantitatively, and further visualized via heat map.

Results

Tooth germs continuously increased in size from Nolla Stage 1 to 6. AMEL expression in the newly formed enamel kept negative, but presented intensively positive in the previously formed enamel from Stage 1 to 3. The adjacent enamel-dentin junction (EDJ) was strongly positive during the whole process. In predentin, AMEL was weakly seen at Stage 1 and then dramatically up-regulated from Stage 2 to Stage 3, then down-regulated but was still apparently seen in the whole process. AMEL expression in dentin was decreased during dentin matrix secretion and mineralization.

Conclusions

This study identified the dynamic distribution of AMEL during porcine tooth crown formation. Semi-quantitative analysis and heat map emerged as reliable indicators in demonstrating AMEL distribution pattern.

中文翻译：

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绘制猪磨牙牙冠发育过程中牙釉蛋白的表达

介绍

牙釉蛋白 (AMEL) 在牙釉质和牙本质基质沉积和矿化过程中起着关键作用。大多数研究集中在 AMEL 在芽、帽和钟形阶段的表达模式。AMEL 蛋白在不同矿化阶段的时空表达，特别是从隐窝的存在到冠完成阶段，仍然未知。因此，研究了从 Nolla 阶段 1 到 6 的牙冠形成中 AMEL 的分布模式。

方法

获得了 Nolla 阶段 1 至 6 的猪下颌磨牙牙胚。用X线片和手术显微镜观察牙胚的动态形态变化。AMEL 蛋白表达通过免疫组织化学评估，然后半定量分析，并通过热图进一步可视化。

结果

Nolla 1-6 期牙胚不断增大。新形成的牙釉质中 AMEL 表达保持阴性，但 1-3 期前形成的牙釉质中呈强阳性表达。相邻的牙釉质 - 牙本质连接处（EDJ）呈强阳性在整个过程中。在predentin中，AMEL在第一阶段弱可见，然后从第二阶段到第三阶段显着上调，然后下调，但在整个过程中仍然明显可见。在牙本质基质分泌和矿化过程中，牙本质中的 AMEL 表达降低。

结论

本研究确定了猪牙冠形成过程中 AMEL 的动态分布。半定量分析和热图成为展示 AMEL 分布模式的可靠指标。