An In Vitro Study For The Detection Rate And The Extension Depth Of Cracked Teeth By Enhanced CBCT

Cracked tooth,the crack extends from the occlusal surface apically,and usually crosses the central fossa to the proximal surface,involving one or two marginal ridges without separation of the two segments.Diagnosis of the cracked teeth is difficult for clinicians.It is because not only the concealment of cracks,not easy to diagnose,but also the difficulty to make a predictable treatment plan,and the long-term prognosis is unpredictable.The symptoms of cracked teeth are not obvious at the early stage,it can cause cold stimulation sensitivity and occlusal discomfort.If the affected teeth are not intervened in time,the cracks will continue to develop and extend to the dentin,even the pulp cavity,causing pulpitis or periapical periodontitis.Therefore,the early detection,diagnosis and treatment of cracked teeth are particularly important.The diagnosis of cracked teeth can be basically established by methylene blue staining,microscope magnification,and so on.However,the key difficulty is that there is no reliable technique to measure the extension depth of crack before the treatment.CBCT has high spatial resolution and strong clinical application value.Compared with PR,CBCT has a higher detection rate of cracks,and CBCT has less radiation and higher clinical practicability compared with Micro-CT.At present,only a few studies have reported the ability of CBCT to diagnose cracked teeth,but there is no report about CBCT to evaluate the depth of crack invasion.Objectives:1.The detection rates of cracked teeth by PR,pre-experimental CBCT(pre-CBCT)and enhanced CBCT were compared in cracked teeth model,and the diagnostic ability of different imaging examination for cracked teeth were observed.2.The correlation between the crack depth measured by enhanced CBCT and Micro-CT was analyzed to evaluate the accuracy of the crack depth measured by enhanced CBCT.And we expect to provide evidence for the measurement of crack depth clinically.Method:The artificial cracked teeth model in vitro was constructed by temperature difference method,and 31 cracked teeth were obtained.PR and CBCT were taken for the cracked teeth,of which the CBCT was named as the pre-CBCT,and Micro-CT was also scanned.Image data was saved in the database.The ioversol was infiltrated into the crown cracks under vacuum,then CBCT was taken again as enhanced CBCT,to observe the development of the cracks.The cracked teeth diagnosed as "cracked" on enhanced CBCT were selected,and the crack depths on Micro-CT and enhanced CBCT were measured respectively.The experimental results were blindly observed by two observers.The results of PR,pre-CBCT and enhanced CBCT were observed.The results of Micro-CT were recorded as the diagnostic criteria of cracked teeth.The intra-class correlation coefficient(ICC)was used to compare the extension depth of crack shown on the enhanced CBCT and Micro-CT.The pearson correlation coefficient and linear regression were used to analyze the crack depth measured by the two methods.Result:1.The sensitivities of PR,pre-CBCT and enhanced CBCT about the diagnosis of cracked teeth were 32.3%,48.4% and 67.7%,respectively.2.The ICC value of crack depths measured by enhanced CBCT and Micro-CT was 0.753(P < 0.05).3.Pearson correlation analysis showed a significant correlation between the crack depths measured on the Micro-CT and enhanced CBCT(r = 0.836,P < 0.001).The linear regression model: crack depths measured on Micro-CT = 2.76 + 0.87 * crack depths measured on enhanced CBCT.Conclusion:Enhanced CBCT using a contrast medium to infiltrate into the crack under vacuum conditions could significantly improve the detection rate of cracked teeth and accurately predict the crack depths.