激光超声纵波用于磨牙内部轮廓无损检测的理论研究  

Theoretical study of laser ultrasonic longitudinal wave applied in the nondestructive detection of inner profile of molars

作　　者：徐海云[1] 梅松[1] 袁玲[1] 沈中华[1] 朱庆萍[2] 倪晓武[1] 陆健[1] Xu Haiyun Mei Song Yuan Ling Shen Zhonghua Zhu Qingping Ni Xiaowu Lu Jian(College of Science,Nanjing University of Science and Technology,Nanjing,210094 ,China The Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, 210029, China)

机构地区：[1]南京理工大学理学院,南京210094 [2]南京医科大学附属口腔医院,南京210029

出　　处：《南京大学学报（自然科学版）》2017年第1期92-100,共9页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金青年基金(61108013);南京理工大学"紫金之星"项目

摘　　要：针对目前口腔医学在临床上对牙齿内部轮廓无法准确检测的问题,提出了利用激光超声纵波检测磨牙内部轮廓的方法.首先利用有限元方法模拟激光辐照牙齿产生超声波的过程,通过CT扫描与三维重建技术获取牙齿的三维模型,建立了超声纵波以及纵波在磨牙中传播的有限元模型.考虑激光在牙釉质中的渗透,修正了等效点声源的位置.选取磨牙上的一个截面,对其进行旋转扫描,并在激发点附近同侧接收得到多组超声信号.通过信号分析,求解纵波在牙釉质—牙本质界面反射点的位置,最终实现牙齿内部轮廓的检测.与牙齿的实际内部轮廓进行比较,结果精度比较高,验证了用激光超声纵波检测牙齿内部轮廓的可行性.最后分析了该方法的误差来源以及其适用条件.研究结果将对牙齿内部结构临床检测提供理论依据和检测方法,有助于激光超声技术在临床医学检测中的进一步发展和应用.Although the external contour information of the teeth is easy to be measured in clinic,the clinical detection of the internal profile-enamel-dentinal junction has not been realized.This paper proposes a method of using laser ultrasonic longitudinal wave to detect the internal profile of the molar.Firstly,the ultrasonic wave generated by the irradiation of the teeth with laser was simulated by the finite element method.Three dimensional model of tooth was acquired by CT scan and 3Dreconstruction technique,and then the finite element model of ultrasonic longitudinal wave and longitudinal wave propagation was established.When the laser was irradiated on the surface of the enamel,some of the laser energy would penetrate into the depth of the enamel.Considering this situation,the position of equivalent point source was modified.One cross section of the molar was selected.Because of the uneven thickness of the enamel in all directions,it was necessary to rotate it.And then multiple ultrasonic signals were received at thesame side of the excitation point.According to the signal analysis,the position of the reflection point of the longitudinal wave in the enamel-dentinal junction（EDJ）was solved,and the detection of inner profile of the tooth was finally realized.Compared with the actual tooth profile,the accuracy of the results is high,which verifies the feasibility of using laser ultrasonic longitudinal wave to detect the inner contour of the teeth.Finally,the error sources of the method and its application conditions were analyzed.The main measurement error is caused by the change of enamel thickness.The results of the study will provide theoretical basis and detection methods for the clinical detection of the internal structure of teeth.It is helpful for the further development and application of laser ultrasonic technology in clinical medicine detection.

关 键 词：激光超声 无损检测 有限元方法 牙齿结构 纵波 

分 类 号：TN24[电子电信—物理电子学]