The mineralization-front theory is historically rooted in mineralization research fields for many decades. This theory is widely used to describe mineralization events in both osteogenesis and dentinogenesis. However, this model does not provide enough evidence to explain how minerals are propagated from the pulp-end dentin to dentin-enamel junction (DEJ). To address this issue, we modified the current research approaches by >a) extending the mineral deposition windows of time from minutes to hours, instead of limiting the mineralization assay on days and weeks only; >b) switching a regular fluorescent microscope to a more powerful confocal microscope; in which both mineral deposition rates and detail mineral labeling along with dentin tubules can be documented; and >c) using reporter mice, including the Gli1-CreERT2 activated tomato and the 2.3 Col1-GFP to mark odontoblast processes combined with mineral dye injections. Our key findings are: 1) Odontoblast-processes, full of numerous mini-branches, evenly spread to entire dentin matrices with a high density of processes and a large diameter of the main process at the predentin-dentin junction; and 2) The minerals deposit along with entire odontoblast-processes and form many individual mineral collars surrounding odontoblast processes. As a result, these merged collars give rise to a single labeled line at the dentin-predentin junction, in which the dental tubules are wider in diameter and denser in odontoblast processes compared to other dentin areas. We therefore propose that it is the odontoblast-process that directly contributes to mineralization, which is not simply limited in the mineralization front at the edge of dentin and predentin, but occurs along with the entire odontoblast process. These new findings will shed new light on our understanding of dentin structure and function, as well as the mechanisms of mineralization.
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机译：矿化前沿理论几十年来一直植根于矿化研究领域。该理论被广泛用于描述成骨和牙本质发生中的矿化事件。但是，该模型没有提供足够的证据来解释矿物质如何从牙髓末端的牙本质扩散到牙本质-牙釉质结合处（DEJ）。为了解决这个问题，我们通过> a 修改了当前的研究方法，将矿物质沉积的时间窗口从几分钟延长到了几小时，而不是将矿化实验的时间限制在几天和几周内； > b ），将常规荧光显微镜切换为功能更强大的共聚焦显微镜；可以记录矿物质沉积速率和详细的矿物质标记以及牙本质小管；和> c ），使用包括Gli1-CreERT2活化番茄和2.3 Col1-GFP在内的报告基因小鼠标记成牙本质母细胞过程与矿物染料注射液的结合。我们的主要发现是：1）成牙本质细胞过程，充满无数的小分支，均匀分布到整个牙本质基质上，具有高的过程密度和前牙本质-牙本质交界处的主要过程的大直径； 2）矿物质与整个成牙本质细胞过程一起沉积，并在成牙本质细胞过程周围形成许多单独的矿物领。结果，这些合并的颈圈在牙本质-前牙本质连接处产生一条标记的线，与其他牙本质区域相比，其中的牙本质小管直径更大，成牙本质过程更密。因此，我们建议成牙本质细胞过程直接促进矿化，这不仅限于牙本质和前牙本质边缘的成矿前沿，而且与整个成牙细胞过程一起发生。这些新发现将为我们对牙本质的结构和功能以及矿化机制的理解提供新的思路。
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