Digital Image Correlation Strain Field Detection System And Its Application In The Diagnosis Of Cracked Teeth

The diagnosis of cracked teeth has always been a key and difficult problem in the field of dentistry.The key point is that the diagnosis is the first to treat the disease,and there is no way to talk about the treatment strategy without diagnosis.The difficulty is that the detection of tooth micro-cracks involves the integration of solid mechanics,inspection science,medicine,materials science and other disciplines.It requires the integration of multidisciplinary knowledge and a "multi-pronged approach" to make a breakthrough.The current common clinical diagnostic methods have certain limitations.In view of the non-destructive testing,high precision,and relatively simple equipment system of DIC technology,this paper proposes a method for image-based non-destructive testing to simulate microcracks of cracked teeth.Based on the Labview platform,the control system and image matching analysis system of the host computer are compiled.The main research contents of this paper are as follows:(1)The design and construction of the detection system.According to the needs of cracked tooth detection,DIC technology is used to detect the small deformation of cracked tooth.Based on the Labview platform,a camera control system and an image detection and analysis system were built to perform in vitro simulated cracked tooth experiments.The DIC detection algorithm in this article is provided by Labview vision toolbox,and its core algorithm is the normalized gray value correlation coefficient.A self-built three-axis motion platform with a telecentric lens is used as an image acquisition system to observe the surface deformation information of the simulated cracked tooth.According to the characteristics of cracked tooth surface compression and deformation under the action of chewing force,the strain value of the area near the crack is abnormally increased as a feature of cracked tooth detection.(2)Perform simulation experiments to analyze the stability and resolution of the system.Use Matlab to generate speckle patterns,apply different displacements or uniform strains,and apply noise to the speckle patterns,test the performance of the matching system,and explore the impact of different matching input parameters on the matching results,and seek a more cost-effective match parameter.(3)A simulated cracked tooth detection experiment was carried out in vitro.Through thermal cycling experiments,they were alternately placed in warm water and liquid nitrogen to prepare an in vitro simulated cracked tooth.Considering the irregular shape of the tooth and it is difficult to load,the cracked tooth was encapsulated and polished with resin.Use a universal testing machine to load the encapsulated cracked tooth.(4)Crack extraction and opening calculation.The crack skeleton is extracted from the data of the principal strain field.And based on crack kinematics,quantitative calculation and visualization of crack opening are carried out.The crack skeleton was extracted from CT images,which verified the usability of the crack detection method proposed in this paper.Finally,the random system error of the detection device was measured and characterized.The detection system in this paper,analyzed from the experimental results,showed sufficient crack detection accuracy.This method can provide a new solution for the rapid clinical diagnosis of cracked teeth,and the calculated crack opening will provide help for subsequent clinical treatment of cracked teeth.