Materials Science and Engineering, University of Florida, 549 Gale Lemerand Dr., Gainesville, FL 32611, USA.
Preventative and Restorative Dental Sciences, University of California San Francisco, 707 Parnassus Ave., San Francisco, CA 94143, USA; Missouri School of Dentistry and Oral Health, A.T. Still University, 800 West Jefferson St., Kirksville, MO 63501, USA.
Dent Mater. 2018 Sep;34(9):1378-1390. doi: 10.1016/j.dental.2018.06.020. Epub 2018 Jun 21.
The polymer-induced liquid-precursor (PILP) mineralization process has been shown to remineralize artificial dentin lesions to levels consistent with those of native dentin. However, nanoindentation revealed that the moduli of those remineralized lesions were only ∼50% that of native dentin. We hypothesize that this may be due to the PILP process having been previously optimized to obtain high amounts (∼70wt%) of intrafibrillar crystals, but without sufficient interfibrillar mineral, another significant component of dentin.
Fluoride was added to the PILP-mineralization of collagen from rat tail tendon at varying concentrations to determine if a better balance of intra- versus inter-fibrillar mineralization could be obtained, as determined by electron microscopy. Nanoindentation was used to determine if fluoridated apatite could improve the mechanical properties of the composites.
Fluoride was successfully incorporated into the PILP-mineralization of rat tail tendon and resulted in collagen-mineral composite systems with the mineral phase of hydroxyapatite containing various levels of fluoridation. As the fluoride concentration increased, the crystals became larger and more rod-like, with an increasing tendency to form on the fibril surfaces rather than the interior. Nanomechanical testing of the mineralized tendons revealed that fluoride addition did not increase modulus over PILP mineralization alone. This likely resulted from the separated nature of collagen fibrils that comprise tendon, which does not provide lateral reinforcement and therefore may not be suited for the compressive loads of nanoindentation.
This work contributes to the development of minimally invasive approaches to caries treatment by determining if collagen can be functionally mineralized.
聚合物诱导的液体前体（PILP）矿化过程已被证明可以使人工牙本质病变再矿化到与天然牙本质相当的水平。然而，纳米压痕测试表明，这些再矿化病变的模量仅约为天然牙本质的 50%。我们假设这可能是因为 PILP 过程之前已经过优化，以获得大量（约 70wt%）纤维内晶体，但没有足够的纤维间矿物质，而纤维间矿物质是牙本质的另一个重要组成部分。
在不同浓度下向来自大鼠尾腱的胶原蛋白的 PILP 矿化中添加氟化物，以确定是否可以获得更好的纤维内与纤维间矿化平衡，通过电子显微镜来确定。纳米压痕测试用于确定氟化磷灰石是否可以改善复合材料的机械性能。
氟化物成功地掺入到 PILP 矿化大鼠尾腱中，得到了羟磷灰石矿物相含有不同氟化物含量的胶原蛋白-矿物复合体系。随着氟化物浓度的增加，晶体变得更大，更棒状，越来越倾向于在纤维表面而不是内部形成。矿化肌腱的纳米力学测试表明，氟化物的添加并没有使模量高于单独的 PILP 矿化。这可能是由于组成肌腱的胶原蛋白纤维的分离性质所致，这种性质不能提供侧向增强，因此可能不适合纳米压痕的压缩载荷。
这项工作通过确定胶原蛋白是否可以进行功能性矿化，为开发微创龋齿治疗方法做出了贡献。
