Assessment Of Using Optical Coherence Tomography A Method To Cracked-tooth Classification Diagnose

Clinical classification of cracked tooth has long been an issue.The small teeth crack,often confined to the enamel,the width of which is difficult to be observed.It's also difficult to be detected before the crack developing into deep dentin.At present,the diagnostic methods used in clinical practice are often based on clinical symptoms.Bite diagnosis as an aid in the diagnosis can only use for symptomatic teeth.In commonly,resolution of CBCT is about 150 microns,and it too low to distinguish of tiny cracks in the image.As new examination methods,OCT and Micro CT,on the other hand,both have high-level resolutions of about 10 microns,and will do no harm to tooth tissues.Especially for Micro CT,which has been widely used in the field of materials engineering,geology,biology,life science for its good isotropic and HD resolution,the images of it have become as the gold-standard in the diagnosis of bone tissue structures by some academics.Micro CT also has great effect on the observation of isolated teeth,and it has been used as the gold standard to verify the microcrack of the dentin for a long time.However,due to the restricted factors of radiation dose and scanning time,it can not be applied directly to human body.Objective: this study was to evaluate the sensitivity and specificity of cracked tooth crown hierarchical diagnostic evaluation when using optical coherence tomography imaging(optical coherence tomography,OCT)as a non-destructive way.And compare the test results with Micro CT's gold standard,analyze their correlations and evaluate the possibility of introducing oral clinical OCT as auxiliary diagnosis methods.Methods: this experiment is designed to in vitro experiment,selecting the in vitro teeth for sample preparation of hidden crack model,and the temperature difference method will be used for making cracked tooth preparation models.At present,there are few references for the preparation method of the dental cleft model.This experiment is to consider the experimental results,The preparation effect was evaluated by OCT,and the changes of light signals before and after the preparation of contrast model were observed.Select randomly to cluster the sample,and compare their observations.OCT and Micro CT were used to detect the model of the hidden teeth and to make the classification diagnosis,and the results of Micro CT were used as the gold standard to evaluate the authenticity and reliability of OCT detection.Statistical analysis was conduced to analyze the rank sum test of the paired-sample data between the two results.Results: 1,OCT could detect all of the tiny cracks within all of the enamel layers including cracks that reaching DEJ interface(Se = 100%).Among the results of experiments,the diagnosis of fissures confining to outer layer enamel are in highest accord with the gold standard(AR = 91.7%),and has the most reliable effect on diagnosing the incomplete teeth cracks occurring in crowns.(YI = 91.4%).Secondly,it extends to the deep enamel crack,and the worst diagnosis value is the enamel surface crack.Also,the diagnostic sensitivity of dentin fissure was lower than that of enamel layer,and the rate of missed diagnosis was higher when the fissure was located more than 1mm under the DEJ.2.The Kappa value shows that OCT is highly consistent with the diagnosis of each group,and is highly reliable Particularly for those fissures located near the surface and extended to deep dentin.(Kappa is greater than 0.75).3.The two samples were compared at the level of alpha =0.05,and p<0.01 which were considered to have significantly different lengths under the two detection methods,OCT and Micro CT,respectively.Because of the negative rank sum,the data measured by OCT is significantly smaller than that of Micro CT.Conclusions: OCT is highly reliable for diagnosing incomplete teeth cracks occurring in crowns,especially for those fissures located within the shallow enamel and dentin fissures located above 1mm-under the DEJ,which conforms broadly to the Micro CT principle.In addition,OCT is suitable for applying to the treatment of dental crown cracks as an early auxiliary diagnosis owing to its rapid imaging,high-definition image,and the advantage of nonradioactive damage,all of which will greatly make contribution to making up the diagnosis technology,intervening early treatment,saving the tooth nerve function,and improving the long-term survival rate.