Research On Autofluorescence Imaging For Detection Technology Of Dental Plaque

The harm of dental caries to human health has been widely concerned.Early dental caries is easily ignored by the existing detection methods in clinical practice.Therefore,how to diagnose early dental caries has become a new research hotspot,which is the main goal of preventing dental caries.Dental plaque is the main factor causing dental caries.In order to realize the non-destructive detection of early dental caries,the detection technology based on autofluorescence imaging of dental plaque was developed in this paper.In this work,the plaque detection method and the fluorescence effects were discussed,and the spectral characteristics of tooth autofluorescence were experimentally verified.In addition,a fluorescence image acquisition system were designed and performed a fluorescence imaging experiment.The experimental results show that autofluorescence imaging can be used to detect dental plaque,which is helpful for the diagnosis of early caries.The main research contents and results are as follows:（1）The spectral measurement experiment based on the autofluorescence effect of biological tissues was designed to investigate the differences in fluorescence spectra of different caries,so as to determine the optimal excitation light source and emission fluorescence band of dental plaque.The excitation and fluorescence spectra of the samples were collected by a fluorescence spectrometer,and the spectral data were preprocessed by the Savitzky-Golay algorithm.The experimental results show that the wavelengths of the excitation peaks for healthy teeth and caries are around 405 nm,the fluorescence band of healthy teeth is mainly concentrated in 450 nm-550 nm,and the fluorescence peak of tooth hard tissue is around 485 nm.The fluorescence peaks of tooth caries lesions are at 623 nm and 685 nm,which are consistent with porphyrin compounds.In addition,the fluorescence intensity between 600nm-700 nm of tooth caries lesions increases with the severity of caries lesions.Therefore,it can be considered that the fluorescence peaks of dental caries lesions are caused by porphyrin compounds,which are metabolites of dental plaque.（2）A fluorescence image acquisition system was designed based on the principle of autofluorescence imaging detection of dental plaque,which could be used to acquire the autofluorescence images of dental plaque.Firstly,from the energy calculation point of view,the excitation light source needs to provide a light intensity of at least 5.039 lx in the detection area to ensure that the emitted fluorescence the photosensitive surface of the CMOS OV5640 image sensor to respond.Then,an image acquisition system based on FPGA was designed,including CMOS driver design and parameter configuration,image data caching and processing and the control design of transmission module.Finally,the design of modules were verified by timing simulation with Questasim,and the fluorescence image acquisition system works.（3）A dental plaque fluorescence imaging system was built,and the autofluorescence imaging detection of dental plaque was verified.In the experiment,the fluorescence images of the isolated teeth were collected under the natural environment,405 nm light source,600 nm-700 nm bandpass filter and 500 nm long-wave filter.The experimental results show that the fluorescence images of healthy teeth are green,while the fluorescence images of carious teeth gradually turn red with the increase of the plaque content.Additionally,the plaque and caries were more obvious in the fluorescence images under the 500 nm long-wave filter.In order to reflect the dental plaque content more intuitively,the collected fluorescence images were processed and analyzed.The experimental results show that the content of dental plaque increases with the degree of dental caries,which is consistent with the medical diagnosis.In conclusion,the autofluorescence imaging system has great potential in detecting dental plaque.