基于超声共振谱方法的人牙釉质材料力学特性研究

目的 基于超声共振谱（resonant ultrasound spectroscopy, RUS）方法研究人牙釉质材料的力学特性。方法 制作长方体状牙釉质样本。估计样本的理论共振频率，与RUS实验测量得到的样本实际共振频率相比较。基于迭代方法调整牙釉质弹性常数，使得理论共振频率和实验共振频率满足均方误差最小准则，并计算弹性模量、剪切模量与泊松比。结果 牙釉质样本的弹性模量、剪切模量和泊松比范围分别为61.52~80.46 GPa、21.51~51.86 GPa和0.18~0.43。如果排除差异较大样本的影响，牙釉质的平均弹性模量、剪切模量和泊松比分别为72.84 GPa、31.94 GPa和0.27。 结论 RUS方法在测量牙釉质力学特性方面具有可行性与重复性无损测量优势，一次测量就可以实现牙釉质所有弹性常数和力学参数的估计，研究结果为牙科修复材料的研发提供参考。
Objective To investigate the mechanical properties of human enamel based on resonant ultrasound spectroscopy (RUS). Methods The rectangular parallelepiped specimens of human enamel were processed. The theoretical resonant frequencies of specimens were estimated and paired with the experimental resonant frequencies measured from RUS experiments. An iterative procedure was used to adjust elastic constants of enamel until the theoretical frequencies corresponded to the experimental frequencies based on minimum mean-squared error criterion. In addition, elastic modulus, shear modulus and Poisson’s ratio were calculated respectively. Results The elastic modulus, shear modulus and Poisson’s ratio ranged from 61.52 to 80.46 GPa, 21.51 to 51.86 GPa and 0.18 to 0.43, respectively. Eliminating the effect of large specimen variances, the average of elastic modulus, shear modulus and Poisson’s ratio was 72.84 GPa, 31.94 GPa and 0.27, respectively. Conclusions RUS performs a feasibility of measuring the mechanical properties of human enamel with repeatable and nondestructive advantages. All the elastic constants and mechanical parameters can be estimated through a signal experiment. The results provide references for the development of biomimetic dental restoration materials.