Background: Great interest has recently been focused on tooth and tooth derivatives as suitable substrates for the treatment of alveolar bone defects. Here, we propose the use of demineralized baby teeth (BT) as potential grafting materials for bone augmentation procedures. Methods: Particles of human BT (Ø < 1 mm) were demineralized by means of a chemical/thermal treatment. Demineralized BT particles were thoroughly characterized by scanning electron microscopy/energy dispersive X-ray analyses to evaluate the effects of the demineralization on BT topography and mineral phase composition, and by enzyme-linked immunosorbent assays (ELISA) to quantify collagen and bone morphogenetic protein-2 (BMP-2) protein contents. The response of SAOS-2 cells to exogenous BMP-2 stimulation was evaluated to identify the minimum BMP-2 concentration able to induce osteodifferentiation in vitro (alkaline phosphatase (ALP) activity). Results: The demineralization treatment led to a dramatic decrease in relative Ca and P content (%) of ≈75% with respect to the native BT particles, while preserving native protein conformation and activity. Interestingly, the demineralization process led to a rise in the bioavailability of BMP-2 in BT particles, as compared to the untreated counterparts. The BMP-2 content found in demineralized BT was also proved to be very effective in enhancing ALP activity, thus in the osteodifferentiation of SAOS-2 cells in vitro, as confirmed by cell experiments performed upon exogenously added BMP-2. Conclusions: In this study we demonstrate that the BMP-2 content found in demineralized BT is very effective in inducing cell osteodifferentiation, and strengthens the idea that BTs are very attractive bioactive materials for bone-grafting procedures.

中文翻译：

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脱矿后人乳牙中 BMP-2 和 I 型胶原蛋白的保存

背景：最近，人们对牙齿和牙齿衍生物作为治疗牙槽骨缺损的合适基质产生了极大的兴趣。在这里，我们建议使用脱矿质乳牙 (BT) 作为骨增强手术的潜在移植材料。方法：人类 BT (Ø < 1 mm) 的颗粒通过化学/热处理脱矿质。通过扫描电子显微镜/能量色散 X 射线分析彻底表征脱矿质 BT 颗粒，以评估脱矿质对 BT 形貌和矿物相组成的影响，并通过酶联免疫吸附测定 (ELISA) 量化胶原蛋白和骨形态发生蛋白- 2 (BMP-2) 蛋白质含量。评估 SAOS-2 细胞对外源性 BMP-2 刺激的反应以确定能够在体外诱导骨分化的最低 BMP-2 浓度（碱性磷酸酶 (ALP) 活性）。结果：相对于天然 BT 颗粒，脱矿质处理导致相对 Ca 和 P 含量 (%) 显着降低约 75%，同时保留了天然蛋白质的构象和活性。有趣的是，与未处理的对应物相比，脱矿质过程导致 BT 颗粒中 BMP-2 的生物利用度增加。在脱矿质 BT 中发现的 BMP-2 含量也被证明在增强 ALP 活性方面​​非常有效，因此在体外 SAOS-2 细胞的骨分化中，正如在外源添加 BMP-2 时进行的细胞实验所证实的那样。结论：