Study Of The Root Canal System Anatomy Of The Mandibular First Premolar In Shandong Province

Endodontics and periapical diseases, which can result in the removal of teeth in severe cases and further affect the masticatory function, are two common diseases against human oral health. Thus it is the responsibility for the oral practitioners to treat for these diseases in order to save the teeth for patients, and root canal therapy (RCT) is the preferred method. Root canals are located in the root without visual images and each root canal system has its own anatomical characteristics due to the individual differences, resulting in the clinical treatment uncertainty and failure. In most cases, mandibular first premolars belong to single-root-single-tube, which is relatively easy to find and clean up. But there have been reports that mandibular first premolar is the site in the full moth with the highest treatment failure rate, certain variations in root canal were ignored by doctors, the apical foramen of missing root canal was not completely closed and trans-infection occurred between the inside and outside of the root canal, causing root canal treatment failure. So the dentists should be familiar with the morphological characteristics of the root canal, in order to provide theoretical support for the clinical treatment.China has vast territory with many ethnic groups. People of different regions and different ethnic groups have variant root canal system anatomy due to the variances of genetic and dietary habits. Reports on the mandibular first molar root canal system morphological characteristics in China are usually located in the south region, however, information about Shandong region population is still lacking. Therefore, this study select the Shandong region population as research objects, tooth clearing technique and the cone-beam CT scan were used to observe the anatomical features of the mandibular first molar root canal and detect variations, aiming to provide information on the root canal anatomy of mandibular first premolar of Shandong region population and further improve the success rate of RCT.Objective:To study the anatomical features of root canal system of mandibular first premolar in Shandong region population and explore the main points of their clinical treatment approach, in order to provide a theoretical basis and anatomical basis for improving the success rate of RCT in mandibular first premolar of Shandong region population.Methods:(1)164mandibular first premolars collected from different regions in Shandong province were used to make transparent dental plates. Root appearance was observed firstly with the naked eye and the number of teeth with root concavity were recorded. Root canal system morphology were observed via transparent tooth specimen.(2)mandibular first premolar images of Shandong population were selected from the cone-beam CT image data of Department of Radiology, Stomatology Hospital of Shandong University, root canal morphology of these teeth were studied.Results:(1)1.22%mandibular first premolar had two roots(2teeth among164teeth, the other162teeth were one root); The morphology of root canal of162single-root teeth were mainly type â…  system, accounting for82.7%while multiple root canal system accounting for17.3%; Among the36teeth with root concavity,21teeth had a single root canal and the other15teeth had two canals, the occurrence rate of two canals was41.7%;18.3%root canal of mandibular first premolar was not single-root-single-tube observed by the transparent teeth specimens(30teeth among164teeth).(2)Among the304samples detected by cone-beam CT scan,55teeth had multiple canals, accounting for18.1%.(3) Variation rate of the468samples included in this study was:(30+55)/(164+304) =18.2%.The probability of double-root was very low, the variations of multiple canals usually occur in a flat root. Teeth with root concavity have a higher probability of multiple canals than teeth without root concavity. Root concavity usually shows an abnormal image of root overlap in buccolingual X-ray films, can be expressed as pairs of root overlap abnormal image, in which exceptions need to be changed vote according to the angle of multiple films, and to determine the root canal morphology.Conclusion:The occurrence rate of multiple root canals in the mandibular first premolar root canal of Shandong region population is relatively high, which should be paid more attention to by dentists.