Department of Clinical Science, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy.
Department of Materials, Environmental Sciences and Urban Planning, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy.
Int J Environ Res Public Health. 2020 Jul 8;17(14):4931. doi: 10.3390/ijerph17144931.
Several studies showed that the sintering temperature of 1250 °C could affect the formation of α-Ca(PO), which is responsible for the reduction of the hardness value of biphasic calcium phosphate biocomposites, but they did not evaluate the inference of the sintering time at peak temperature on transition of β-Ca(PO) to α-Ca(PO). This analysis explored, in an innovative way, inferences and correlations between volumetric microstructure, mechanical properties, sintering temperature, and time at peak temperature in order to find the best sintering conditions for biphasic calcium phosphate composites grafted in severe alveolar bone defects.
Sintered biphasic calcium phosphates (30%-hydroxyapatite/70%-tricalcium phosphate) were tested by microCT imaging for the 3D morphometric analysis, by compressive loading to find their mechanical parameters, and by X-ray diffraction to quantify the phases via Rietveld refinement for different sintering temperatures and times at the peak temperature. Data were analysed in terms of statistical inference using Pearson's correlation coefficients.
All the studied scaffolds closely mimicked the alveolar organization of the jawbone, independently on the sintering temperatures and times; however, mechanical testing revealed that the group with peak temperature, which lasted for 2 hours at 1250 °C, showed the highest strength both at the ultimate point and at fracture point.
The good mechanical performances of the group with peak temperature, which lasted for 2 hours at 1250 °C, is most likely due to the absence of the α-Ca(PO) phase, as revealed by X-ray diffraction. However, we detected its presence after sintering at the same peak temperature for longer times, showing the time-dependence, combined with the temperature-dependence, of the β-Ca(PO) to α-Ca(PO) transition.
几项研究表明，1250°C 的烧结温度可能会影响 α-Ca(PO) 的形成，这是导致双相磷酸钙生物复合材料硬度值降低的原因，但它们并未评估峰值温度下烧结时间对 β-Ca(PO)向 α-Ca(PO)转变的影响。本分析以创新的方式探索了体积微观结构、力学性能、烧结温度和峰值温度下的烧结时间之间的推断和相关性，以便为严重牙槽骨缺损中接枝的双相磷酸钙复合材料找到最佳的烧结条件。
通过微 CT 成像对烧结的双相磷酸钙（30%-羟基磷灰石/70%-磷酸三钙）进行 3D 形态计量分析，通过压缩加载来确定其力学参数，并通过 X 射线衍射对不同烧结温度和峰值温度下的时间进行 Rietveld 精修以定量相。使用 Pearson 相关系数对数据进行统计推断分析。
所有研究的支架都独立于烧结温度和时间，紧密模仿颌骨的牙槽组织；然而，力学测试表明，在 1250°C 下持续 2 小时的峰值温度组在极限点和断裂点都表现出最高的强度。
在 1250°C 下持续 2 小时的峰值温度组具有良好的力学性能，这很可能是由于 X 射线衍射显示不存在 α-Ca(PO)相。然而，我们在相同的峰值温度下烧结更长时间后检测到其存在，表明β-Ca(PO)向 α-Ca(PO)转变具有时间依赖性，同时也具有温度依赖性。
